Patent Publication Number: US-6661650-B2

Title: Electronic apparatus with cover for component having a wall to clamp the keyboard

Description:
This application is a continuation of U.S. Ser. No. 09/739,626 filed Dec. 20, 2000 now abandoned, which is a divisional of U.S. Ser. No. 09/105,177 filed Jun. 26, 1998 now U.S. Pat. No. 6,198,626, which is a continuation of U.S. Ser. No. 08/688,846 filed Jul. 31, 1996 now U.S. Pat. No. 5,808,861 and claims priority to Japanese document 7-263637 filed Sep. 19, 1995, the contents of which are incorporated herein in their entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a portable apparatus such as a book-type portable computer, and more particularly to a structure having a housing containing a functional component such as a speaker. 
     2. Description of the Related Art 
     In the field of conventional portable computers dealing mainly with character information and graphic information, there is a tendency that such portable computers should be applied to multimedia wherein moving pictures, sounds, etc. are integrated. The amount of data processed in multimedia is much greater than that of data processed when character information alone is used. It is thus necessary to record data by using a large-capacity optical disk. To meet the demand, portable computers have been marketed, which comprise CD-ROM drives for reading out data from optical disks. 
     This type of portable computer includes a box-shaped housing body and a display unit supported by the housing body. The CD-ROM driver is contained within the housing body. The portable computer including the CD-ROM drive is provided with various functional parts, e.g. a loudspeaker outputting a sound and a volume switch for controlling the volume of sound. These functional parts are contained within the housing body. 
     In the conventional portable computer, the housing body comprises a lower housing and an upper housing coupled to the lower housing. The lower housing supports the CD-ROM drive and functional parts. Thus, after the CD-ROM drive and functional parts are built in the lower housing, the upper housing is removably coupled to the lower housing. The CD-ROM drive and functional parts are covered by the upper housing. 
     In the field of computers having CD-ROM drives, there is a demand that the built-in loudspeaker be replaced with one having higher quality. Besides, the contact of the volume switch for controlling the sound volume may be deteriorated with the passing of use time of the computer. Thus, the frequency of replacement of functional parts such as the loudspeaker and volume switch is relatively higher than that of the CD-ROM drive or other circuit elements contained within the housing body. 
     In the conventional computer, however, the functional parts such as a loudspeaker and a volume switch are contained within the housing body along with the CD-ROM drive and other circuit elements. When such functional parts need to be replaced or maintained, it is necessary to disassembling the entire housing body by removing the upper housing from the lower housing. Consequently, a great deal of time and labor is needed for replacement and maintenance of the functional parts. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide a portable apparatus with high workability capable of easily replacing or maintaining a functional component, without disassembling a housing body. 
     Another object of the invention is to provide a portable apparatus capable of having such an external appearance that first and second speakers are arranged symmetrically with respect to a center line of a housing body. 
     In order to achieve the above objects, there is provided a portable apparatus comprising: 
     a box-shaped housing body including a lower housing and an upper housing coupled to said lower housing, said upper housing including a component attachment portion opened upward; 
     a functional component removably supported on said component attachment portion of said upper housing; and 
     a top cover removably supported on said housing body, said top cover covering the component attachment portion and the functional component supported on said component attachment portion. 
     According to this structure, the functional component is supported on the component attachment portion of the upper housing. The functional component is situated on an upper part of the housing body and not in a deep region of the housing body. Since the functional component supported on the component attachment portion is covered by the removable top cover, the top cover is removed from the housing body and the functional component is exposed to the upper part of the housing body when the functional component is replaced or maintained. Thereby, there is no need to perform time-consuming works such as disassembling the housing body at each time of replacing or maintaining the functional component. 
     According to this invention, there is also provided a portable apparatus comprising: 
     a box-shaped housing body including a lower housing having a bottom wall and a rear wall continuous with the bottom wall, and an upper housing coupled to the lower housing, said upper housing including a component attachment portion opened upward; 
     a functional component removably supported on said component attachment portion of said housing body; 
     a display unit having a support portion extending toward the component attachment portion of said housing body; 
     hinge means for rotatably supporting the display unit on said housing body, said hinge means being situated adjacent to said component attachment portion; and 
     a top cover removably attached to said housing body, said top cover covering the component attachment portion and the functional component supported on said component attachment portion, 
     wherein said component attachment portion of the housing body includes a cover portion covering the support portion of the display unit from below, and being continuous with the rear wall of the lower housing, and 
     said top cover includes a hinge cover portion covering the hinge means, said hinge cover portion being continuous with said cover portion when said top cover is attached to said housing body. 
     According to this structure, the functional component is supported on the component attachment portion of the upper housing. The functional component is situated on an upper part of the housing body and not in a deep region of the housing body. Since the functional component supported on the component attachment portion is covered by the removable top cover, the top cover is removed from the housing body and the functional component is exposed to the upper part of the housing body when the functional component is replaced or maintained. Thereby, there is no need to perform time-consuming works such as disassembling the housing body at each time of replacing or maintaining the functional component. 
     In addition, the cover portion of the component attachment portion extends below the leg portion of the display unit and is continuous with the rear wall of the lower housing. In the state in which the component attachment portion is covered by the top cover, the hinge means can be covered by the hinge cover portion of the top cover and the cover portion. Thus, there is no need to provide an exclusive-use cover for covering the hinge means, and the number of structural parts can be reduced. In addition, since the cover portion is integrated with the component attachment portion, the cover portion can be exactly positioned in relation to the support portion and top cover. 
     According to this invention, there is also provided a portable apparatus comprising: 
     a box-shaped housing body having an upper wall, said upper wall of the housing body having a component attachment portion opened upward; 
     first and second speakers removably supported on said component attachment portion of the housing body, said speakers being arranged on both sides of a center line extending in the depth direction of the housing body through the center of the housing body in the width direction, and a distance between said first speaker and said center line being different from a distance between said second speaker and said center line; and 
     a top cover removably supported on said housing body, said top cover covering the component attachment portion and the first and second speakers; 
     wherein said top cover includes a panel having a pair of holes facing said first and second speakers, and first and second speaker covers attached to the panel and covering said holes, each of said first and second speaker covers having a shape greater than an opening shape of each of said holes and extending in the width direction of said housing body, and a distance between said first speaker cover and said center line being equal to a distance between said second speaker cover and said center line. 
     According to this structure, if the top cover is removed from the housing body, the first and second speakers are exposed to the upper side of the housing body. Thus, there is no need to disassemble the entire housing at each time of replacing or maintaining the speakers, and the workability is enhanced. 
     In addition, since the speaker covers covering the first and second speakers are arranged symmetrical with respect to the center line of the housing body, the speakers may be apparently viewed to be arranged symmetrical with respect to the center line although the speakers are actually arranged asymmetrical. 
     According to this invention, there is also provided a portable apparatus comprising: 
     a box-shaped housing body including a lower housing and an upper housing coupled to said lower housing, said upper housing including a component attachment portion opened upward and a keyboard attachment portion; 
     a keyboard mounted on said keyboard attachment portion; 
     a functional component removably supported on said component attachment portion; and 
     a top cover removably supported on said housing body, said top cover covering the component attachment portion and the functional component supported on said component attachment portion. 
     According to this structure, the functional component is situated on the upper part of the housing body, and not in a deep region of the housing body. The top cover is removed and the functional component is exposed to the upper side of the housing body when the functional component is replaced or maintained. Thereby, there is no need to disassemble the housing body at each time of replacing or maintaining the functional component, and the workability is enhanced. 
     Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out in the appended claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate a presently preferred embodiment of the invention and, together with the general description given above and the detailed description of the preferred embodiment given below, serve to explain the principles of the invention. 
     FIG. 1 is a perspective view showing a portable computer according to the present invention; 
     FIG. 2 is a perspective view of the portable computer, showing the bottom side of a housing body thereof; 
     FIG. 3 is a perspective view of the portable computer, showing the state in which a front cover is rotated to a second position and a battery pack is drawn out of a battery storage section; 
     FIG. 4 is a front view of the housing body, showing the state in which the front cover is rotated to a first position; 
     FIG. 5A is a cross-sectional view of the battery storage section of the housing body; 
     FIG. 5B is a cross-sectional view of a region A in FIG. 5A; 
     FIG. 6 is a side view of the battery pack; 
     FIG. 7 is a cross-sectional view of the battery pack; 
     FIG. 8 is a perspective view showing the state in which a frame is mounted on a lower housing; 
     FIG. 9 is a plan view of the lower housing, showing the state in which the front cover is rotated to the first position; 
     FIG. 10 is a front view of the lower housing, showing the state in which the front cover is rotated to the second position; 
     FIG. 11 is a perspective view of the battery storage section in which an auxiliary battery and a clock battery are mounted; 
     FIG. 12 is a perspective view showing the relationship between the battery storage section and a reinforcement portion of the frame in an exploded manner; 
     FIG. 13 is a rear view of the portable computer; 
     FIG. 14 is a cross-sectional view of the portable computer, showing a loudspeaker attachment portion; 
     FIG. 15 is a cross-sectional view showing the relationship between a second connector cover and a stopper; 
     FIG. 16 is a perspective view of the portable computer showing the state in which the second connector cover is opened; 
     FIG. 17 is a cross-sectional view of the portable computer, showing a TCP mounting portion and a second icon attachment portion; 
     FIG. 18 is a cross-sectional view of the portable computer, showing an extension area of the housing body and the loudspeaker attachment portion; 
     FIG. 19A is a perspective view of the portable computer, showing an attachment portion for a cover unit; 
     FIG. 19B is a perspective view of the portable computer, showing in an exploded manner the state in which the cover unit is removed from the housing body; 
     FIG. 20 is a side view of the portable computer, showing an attachment portion for a connector cover; 
     FIG. 21A is a cross-sectional view of the housing body, showing the attachment portion for the connector cover; 
     FIG. 21B is a cross-sectional view of the housing body, showing the state in which the connector cover is slid to a closed position; 
     FIG. 21C is a cross-sectional view of the housing body, showing the state in which the connector cover is slid to an open position; 
     FIG. 22 is a perspective view showing in an exploded manner the state in which first and second relay connectors are removed from the frame; 
     FIG. 23 is a perspective view showing the state in which a CD-ROM drive and a floppy disk drive are removed from a pack storage section of the housing body; 
     FIG. 24 is a perspective view of the CD-ROM drive; 
     FIG. 25 is a perspective view showing in an exploded manner the state in which a connector hold frame, a connector holder and an outer cover are removed from a cabinet of the CD-ROM drive; 
     FIG. 26 is a plan view of the CD-ROM drive, showing an attachment portion for an interface connector in cross section; 
     FIG. 27 is a perspective view of the floppy disk drive; 
     FIG. 28 is a perspective view of the floppy disk drive, showing the attachment portion for the interface connector in an exploded manner; 
     FIG. 29A is a cross-sectional view of the floppy disk drive; 
     FIG. 29B is an enlarged cross-sectional view of the attachment portion of the interface connector; 
     FIG. 30A is a cross-sectional view of a front half portion of the portable computer; 
     FIG. 30B is an enlarged cross-sectional view of an attachment portion for a first icon; 
     FIG. 31 is a cross-sectional view showing the state in which the front cover is rotated to the second position and a hard disk drive is drawn out; 
     FIG. 32 is a front view of the lower housing, showing the state in which the front cover is rotated to the second position; 
     FIG. 33A is a front view of the lower housing, showing the state in which the front cover is slid to a locked position; 
     FIG. 33B is a front view of the lower housing, showing the state in which the front cover is slid to an unlocked position; 
     FIG. 34A is a cross-sectional view showing the state in which a first engaging projection is hooked on the lower housing; 
     FIG. 34B is a cross-sectional view showing the state in which the first engaging projection is unhooked from the lower housing; 
     FIG. 35A is a cross-sectional view showing the state in which a second engaging projection is hooked in an engaging hole in the frame; 
     FIG. 35B is a cross-sectional view showing the state in which the second engaging projection is unhooked from the engaging hole in the frame; 
     FIG. 36A is a cross-sectional view showing the state in which a third engaging projection is hooked in an engaging hole in the frame; 
     FIG. 36B is a cross-sectional view showing the state in which the third engaging projection is unhooked from the engaging hole in the frame; 
     FIG. 37 is a perspective view showing the relationship between a pushing projection of the front cover and a stopper; 
     FIG. 38A is a cross-sectional view showing the state in which the front cover is rotated to the second position and the pushing projection is disengaged from the stopper; 
     FIG. 38B is a cross-sectional view showing the state in which the front cover is rotated to the first position and the pushing projection pushes up the stopper; 
     FIG. 38C is a cross-sectional view showing the state in which the front cover is slid to the locked position; 
     FIG. 39 is a cross-sectional view showing the state in which an ejector is covered by the front cover rotated to the first position; 
     FIG. 40 is a cross-sectional view showing the state in which the front cover is rotated to the second position and the CD-ROM drive is pulled out by the ejector; 
     FIG. 41 is a plan view showing the positional relationship between the CD-ROM drive and the ejector; 
     FIG. 42 is a rear view showing the state in which a display unit is attached to a component attachment portion of the upper housing; 
     FIG. 43A is a left-hand side view showing the state in which the display unit is attached to the component attachment portion of the upper housing; 
     FIG. 43B is a right-hand side view showing the state in which the display unit is attached to the component attachment portion of the upper housing; 
     FIG. 44 is a perspective view of the portable computer, showing the state in which a top cover is removed from the component attachment portion of the upper housing; 
     FIG. 45 is a perspective view showing a coupling portion between a first leg portion of the display unit and the component attachment portion; 
     FIG. 46 is a perspective view showing a coupling portion between a second leg portion of the display unit and the component attachment portion; 
     FIG. 47 is a cross-sectional view of the portable computer, showing the state in which the top cover is removed from the component attachment portion of the upper housing; 
     FIG. 48 is a cross-sectional view of a region corresponding to the component attachment portion of the housing body; 
     FIG. 49 is a cross-sectional view of a region corresponding to the component attachment portion of the housing body; 
     FIG. 50 is a perspective view showing in an exploded manner the state in which a volume dial is removed from a volume switch; 
     FIG. 51 is a perspective view of the volume dial; 
     FIG. 52 is a cross-sectional view showing the relationship between the volume dial and a panel of the top cover; 
     FIG. 53 is a cross-sectional view taken along line  53 — 53  in FIG. 52; 
     FIG. 54A is a cross-sectional view showing the relationship between the panel of the top cover and a loudspeaker cover; and 
     FIG. 54B is a cross-sectional view showing the state in which the loudspeaker cover is attached to the panel of the top cover. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     An embodiment of the present invention, which is applied to a portable computer, will now be described with reference to the accompanying drawings. 
     FIG. 1 shows a book-type portable computer  1  of “A4” size. The computer  1  comprises a housing body  2  of a synthetic resin and a display unit  3  supported on the housing body  2 . The housing body  2  comprises a lower housing  5  opening upward and an upper housing  6  detachably coupled to an upper end portion of the lower housing  5 . As is shown in FIGS. 2 and 8, the lower housing  5  has a flat bottom wall  5   a , side walls  5   b  and  5   c , and a rear wall  5   d . The side walls  5   b  and  5   c  and rear wall  5   d  extend upward from a peripheral portion of the bottom wall  5   a.    
     The upper housing  6  has a plate shape and includes a substantially flat upper wall  6   a . The upper wall  6   a  faces the bottom wall  5   a  of the lower housing  5 . Side edge portions of the upper wall  6   a  are continuous with the upper end portions of the side walls  5   b  and  5   c  of lower housing  5 . Thus, the housing body  2  has a flat rectangular box-like shape with an opening on the front side. 
     As is shown in FIGS. 2,  4  and  5 A, the lower housing  5  has a battery storage section  8 . The battery storage section  8  is formed as a recess opening to the bottom wall  5   a . The battery storage section  8  extends in the depth direction of the lower housing  5  in a left-hand region of the lower housing  5 . The battery storage section  8  has an insertion hole  9  opening to the front side of the lower housing  5 . 
     The battery storage section  8 , as shown in FIG. 5A, is defined by a pair of upright walls  10   a  and  10   b  extending in the depth direction of the lower housing  5 , and a ceiling wall  11  connecting the upper end portions of the upright walls  10   a  and  10   b . The upright walls  10   a  and  10   b  are spaced apart from each other in the width direction of the housing body  2 . The upright walls  10   a  and  10   b  extend upward from the bottom wall  5   a  and project within the lower housing  5 . The ceiling wall  11  is horizontally situated at an upwardly opening end of the lower housing  5  in parallel to the bottom wall  5   a . The upright walls  10   a  and  10   b  have mutually facing inner surfaces. A guide recess  12  is formed in the inner surface of one of the upright walls, i.e. upright wall  10   a . A guide rail  13  is formed on a lower part of the inner surface of the other upright wall  10   b . The guide recess  12  and guide rail  13  extend in the depth direction of the lower housing  5 . In addition, as shown in FIG. 14, a connector lead-out port  14  opens at a terminal end portion of the battery storage section  8 . The connector lead-out port  14  communicates with the inside of the lower housing  5 . 
     As is shown in FIG. 3, a battery pack  16  is removably mounted in the battery storage section  8 . The battery pack  16  serves as a drive power supply for the computer  1  when the computer  1  is used at a place where no commercial power supply is available. As is shown in FIGS. 6 and 7, the battery pack  16  comprises a battery case  17  of a synthetic resin and a plurality of secondary batteries  18  contained in the battery case  17 . 
     The battery case  17  has a rectangular box shape having a longitudinal axis X 1  extending in the depth direction of the lower housing  5  and a transverse axis X 2  extending in the width direction of the lower housing  5 . The battery case  17  is removably inserted into the battery storage section  8  via the insertion hole  9 . The battery case  17  has such a size that it can be fitted in the battery storage section  8 . Each secondary battery  18  has a cylindrical shape extending in the direction of the transverse axis X 2  of the battery case  17 . The secondary batteries  18  are arranged in the direction of the longitudinal axis X 1  of the battery case  17 . Each secondary battery  18  has a first end provided with a positive terminal  18   a  and a second end provided with a negative terminal  18   b . The secondary batteries  18  are contained within the battery case  17  such that their positive terminals  18   a  and negative terminals  18   b  are alternately arranged in opposite directions. 
     The battery case  17  has a pair of side surfaces opposed to each other with the secondary batteries  18  interposed. The side surfaces of the battery case  17  extend along the longitudinal axis X 1 , and are provided with laterally protruding projections  20   a  and  20   b . The projections  20   a  and  20   b  serve as guides when the battery case  17  is inserted into the battery storage section  8 . One of the projections, i.e. projection  20   a , is slidably engageable in the guide recess  12  in the upright wall  10   a . The other projection  20   b  is engageable with the guide rail  13  on the upright wall  10   b . Thus, the battery case  17  is held in the battery storage section  8  by the engagement between the projection  20   a  and guide recess  12  and the engagement between the projection  20   b  and guide rail  13 . When the battery case  17  is held in the battery storage section  8 , the bottom surface of the battery case  17  is situated in the same plane as the bottom wall  5   a  of the lower housing  5 . 
     As is shown in FIG. 7, the insides of the projections  20   a  and  20   b  are open to the inside of the battery case  17 . The insides of the projections  20   a  and  20   b  define terminal storage sections  21   a  and  21   b  extending in the direction of the longitudinal axis X 1 . The terminal storage sections  21   a  and  21   b  face the positive terminals  18   a  and negative terminals  18   b  of the secondary batteries  18 . A plurality of connection terminals  22  are disposed in the terminal storage sections  21   a  and  21   b . The connection terminals  22  function to electrically connect the positive terminal  18   a  and negative terminal  18   b  of two adjacent secondary batteries  18 . The secondary batteries  18  are connected in series via the connection terminals  22 . The secondary batteries  18  are connected to a positive (+) electrode  23  and a negative (−) electrode  24 . These electrodes  23  and  24  are disposed on one end face of the battery case  17  in the direction of the longitudinal axis X 1 . When the battery case  17  is inserted in the battery storage section  8 , the electrodes  23  and  24  face the connector lead-out port  14 . 
     As is shown in FIGS. 5A and 5B, a recess portion  26  is formed at a corner defined by the right-hand upright wall  10   b  and the ceiling wall  11  of the battery storage section  8 . The recess portion  26  extends in the depth direction of the lower housing  5 . The recess portion  26  has a projection  26   a  protruding to the inside of the battery storage section  8 . The projection  26   a  is engaged in a stepped portion  17   a  defined by the right-hand side surface and right-hand projection  20   b  of the battery case  17 . 
     As is shown in FIGS. 3 and 6, a cover attachment portion  17   b  is formed on an end face of the battery case  17 , which is opposed to the end face thereof on which the electrodes  23  and  24  are disposed. A battery cover  27  is detachably attached to the cover attachment portion  17   b . When the battery pack  16  is completely inserted in the battery storage section  8 , the battery cover  27  is located on the front end portion of the lower housing  5 . The battery cover  27  is slidable between an engaged position where it is engaged with the front end portion of the lower housing  5  and a disengaged position where it is disengaged from the front end portion of the lower housing  5 . Thus, when the battery cover  27  is slid to the engaged position, the battery pack  16  is held in the battery storage section  8  in a locked manner. In the state in which the battery cover  27  is slid to the engaged position, the battery cover  27  is continuous with the bottom wall  5   a  and left-hand side wall  5   b  of the lower housing  5  and the insertion hole  9  of the battery storage section  8  is hidden from the front. 
     As is shown in FIG. 8, a frame  30  is contained within the lower housing  5 . The frame  30  is formed of a light-weight, heat-conductive metallic material such as a magnesium alloy. The frame  30  has such a size that it is fitted in the lower housing  5 . The frame  30  integrally comprises a pack storage section  31  and a board support portion  32 . The pack storage section  31  is situated adjacent to the battery storage section  8  in front half part of the frame  30 . As is shown in FIGS. 8 and 10, the pack storage section  31  includes a bottom wall  33 , a pair of side walls  34   a  and  34   b  continuous with the bottom wall  33 , and a rear wall  35  continuous with the bottom wall  33  and side walls  34   a  and  34   b . The pack storage section  31  has a box shape, opening upward and forward of the lower housing  5 . 
     The pack storage section  31  is divided into a first section  38  and a second section  39  by means of a partition wall  37 . The first section  38  and second section  39  are arranged in the width direction of the lower housing  5 . The first section  38  is adjacent to the battery storage section  8 . The first and second sections  38  and  39  have insertion holes  40  and  41  opening to the front side, as shown in FIGS. 10 and 23. The insertion holes  40  and  41  are located at the front end of the lower housing  5 . 
     As is shown in FIGS. 8 and 22, the board support portion  32  of the frame  30  extends in the width direction of the lower housing  5  in rear of the battery storage section  8  and pack storage section  31 . As is clear from FIG. 17, the board support portion  32  has a bottom wall  44  and a support wall  45  continuous with the bottom wall  44 . The bottom wall  44  is continuous with the bottom wall  33  of pack storage section  31 , and the support wall  45  is continuous with the rear wall  35  of pack storage section  31 . 
     The frame  30 , as shown in FIGS. 5A and 12, has a reinforcement wall  46  integrally. The reinforcement wall  46  comprises a first wall portion  47  extending horizontal and continuous with the left-hand side wall  34   a  of the pack storage section  31 , and a second wall portion  48  extending downward from a distal end of the first wall portion  47 . The first wall portion  47  is superposed on the ceiling wall  11  of the battery storage section  8 . The second wall portion  48  extends in the depth direction of the lower housing  5  and a rear end portion thereof is continuous with the support wall  45  of the board support portion  32 . The second wall portion  48  is fitted between the upright wall  10   a  of the battery storage section  8  and the side wall  5   b  of the lower housing  5 ., Thus, the reinforcement wall  46  surrounds the battery storage section  8  within the lower housing  5 . 
     As shown in FIGS. 5A and 5B, the left-hand side wall  34   a  of the pack storage section  31  is adjacent to the upright wall  10   b  of the battery storage section  8 . An inwardly protruding projection  50  is formed at a corner portion defined by the side wall  34   a  and the first wall portion  47  of reinforcement wall  46 . The projection  50  extends in the depth direction of the lower housing  5 . The projection  50  enters the recess portion  26  of the battery storage section  8 . The projection  50  has a groove-like wiring passage  51  opening to the upper surface of the first wall portion  47 . The wiring passage  51  extends in the depth direction of the lower housing  5 , and a rear end portion thereof is continuous with the board support portion  32 . 
     As is shown in FIGS. 8,  9  and  11 , a battery hold section  53  is formed on the upper surface of the ceiling wall  11  of the battery storage section  8 . The battery hold section  53  is continuous with the wiring passage  51 . An auxiliary battery  54  and a clock battery  55  are held by the battery hold section  53 . The auxiliary battery  54  and clock battery  55  have lead lines  54   a  and  55   a  respectively. The lead lines  54   a  and  55   a  are led to the board support portion  32  via the wiring passage  51 . An opening end portion of the wiring passage  51  is covered with a synthetic-resin insulating sheet  56 . The insulating sheet  56  is attached on the upper surface of the first wall portion  47 . The presence of the insulating sheet  56  prevents the lead lines  54   a  and  55   a  from being removed from the wiring passage  51 . 
     As is shown in FIGS. 14 and 17, a first circuit board  60  is supported at a lower end of the frame  30 . The first circuit board  60  has such a size that it covers the bottom side of the pack storage section  31  and board support portion  32 . The first circuit board  60  is contained within the lower housing  5  in parallel to the bottom wall  5   a  of the lower housing  5 . A rear end portion of the first circuit board  60  is adjacent to the rear wall  5   d  of the lower housing  5 . As is shown in FIG. 13, the rear end portion of the first circuit board  60  is provided with an RGB connector  62  for connection with an external CRT display  61 ; a COMMS connector  64  for connection with a peripheral device  63  of RS-232C Standard; an extension connector  66  for connection with an extension station  65 ; a parallel connector  68  for connection with a printer  67 ; and a power supply connector  70  for connection with a power supply plug  69 . The connectors  62 ,  64 ,  66 ,  68  and  70  are arranged substantially linearly in the width direction of the lower housing  5 . 
     A metallic shield plate  73  is provided on the rear end portion of the first circuit board  60 . The shield plate  73  covers, from the rear side, the connection portion between the connectors  62 ,  64 ,  66 ,  68  and  70  and the first circuit board  60 . The connectors  62 ,  64 ,  66 ,  68  and  70  are exposed to the rear wall  5   d  of lower housing  5 . A first connector cover  74  and a second connector cover  75  are attached to the rear wall  5   d . The first connector cover  74  is situated in a position corresponding to the RGB connector  62  and COMMS connector  64 . The second connector cover  75  is situated in a position corresponding to the parallel connector  68 . The first and second connector covers  74  and  75  are formed of a synthetic resin and have rectangular plate-like shapes. The connector covers  74  and  75  are supported on the lower housing  5  so as to be rotatable between a closed position where they cover, from the rear side, the connectors  62 ,  64  and  68  and an open position where they turn rearward of the lower housing  5  and expose the connectors  62 ,  64  and  68 . A third connector cover  76  is disposed between the first connector cover  74  and second connector cover  75 . The third connector cover  76  is associated with the extension connector  66  and is openably supported on the shield plate  73 . 
     As is shown in FIGS. 13 to  16 , the rear wall  5   d  of lower housing  5  is provided with a pair of rearwardly projecting stoppers  77   a  and  77   b . The stoppers  77   a  and  77   b  are disposed in positions corresponding to the first and second connector covers  74  and  75  respectively. When the first and second connector covers  74  and  75  are rotated about 90° from the closed position to the open position, the stoppers  77   a  and  77   b  abut upon the lower end portions of the connector covers  74  and  75 , thereby limiting further rotation of the first and second connector covers  74  and  75 . 
     Thus, when the first and second connector covers  74  and  75  are rotated to the open position and situated substantially horizontal, the rotation thereof is stopped. For example, when the computer  1  is placed on the top plate of the desk, the first and second connector covers  74  and  75  are not caught between the computer  1  and the top plate of the desk, thus preventing breakage of the connector covers  74  and  75 . 
     According to this structure, what is required is only to form the stoppers  77   a  and  77   b  integral with the rear wall  5   d  of the lower housing  5 , and there is no need to provide special parts for limiting the rotation of the connector covers  74  and  75 . The structure of the housing body  2  is not complicated. 
     As is shown in FIGS. 8,  14  and  17 , second to fourth circuit boards  81 ,  82  and  83  are screwed down to the board support portion  32  of the frame  30 . The second circuit board  81  and third circuit board  82  are situated behind the battery storage section  8  and the first section  38  of the pack storage section  31 . The second and third circuit boards  81  and  82  are arranged above the first circuit board  60  substantially in parallel to the first circuit board  60 . The second circuit board  81  is disposed substantially in the same plane as the ceiling wall  11  of battery storage section  8  and the reinforcement wall  46  of frame  30 . The lead lines  54   a  and  55   a  passed through the wiring passage  51  are connected to the second circuit board  81  via a connector  84 . 
     As is shown in FIG. 17, the third circuit board  82  is a power supply board and interposed between the second circuit board  81  and the bottom wall  44  of the frame  30 . A power supply circuit component  85 , which generates heat in operation, and a battery connector  86  are mounted on the bottom surface of the third circuit board  82 . The battery connector  86  is exposed to the inside of the battery storage section  8  via the connector lead-out port  14 . The battery connector  86  is put in contact with the positive (+) electrode  23  and negative (−) electrode  24  of the battery pack  16 . 
     As is shown in FIG. 8, the fourth circuit board  83  is disposed behind the second section  39  of the pack storage section  31 . The fourth circuit board  83  is situated above the first circuit board  60  substantially in parallel to the first circuit board  60 . 
     A TCP (Tape Carrier Package)  90  functioning as CPU is mounted on the lower surface of the first circuit board  60 , as shown in FIG.  17 . The amount of heat generated by the TCP  90  in operation is very great because of high-speed, large-capacity processing of the computer  1 . A rectangular through-hole  91  is formed in the first circuit board  60  in a region facing the TCP  90 . A cold plate  92  for enhancing the heat radiation performance of the TCP  90  is attached to the first circuit board  60 . The cold plate  92  is formed of a copper alloy with high heat conductivity and is screwed down to the upper surface of the first circuit board  60 . The cold plate  92  has a heat receiving portion  93  fitted in the through-hole  91 . The lower surface of the heat receiving portion  93  is located substantially in the same plane as the lower surface of the first circuit board  60 . The TCP  90  is attached to the lower surface of the heat receiving portion  93  by means of a heat-conductive adhesive. 
     A TCP cover  95  is attached to the lower surface of the first circuit board  60 . The TCP cover  95  has a metallic cover panel  96  with excellent heat conductivity. The cover panel  96  is put in contact with the TCP  90  with a heat-conductive, elastic sheet  97  interposed therebetween. If the TCP  90  generates heat, the heat of the TCP  90  is escaped to the cold plate  92  and TCP cover  95 . 
     The cold plate  92  faces the bottom wall  44  of the board support portion  32 . A heat radiation plate  99  is attached to the bottom wall  44 . The radiation plate  99  is formed of an aluminum alloy with excellent heat conductivity. The radiation plate  99  is in contact with the cold plate  92  without gap. The radiation plate  99  is put in contact with the bottom wall  44  with a heat-conductive, elastic sheet  100  interposed. Thus, the heat of the TCP  90  transmitted to the cold plate  92  is escaped to the radiation plate  99  and then diffused to the frame  30  via the radiation plate  99 . 
     As is shown in FIG. 17, the radiation plate  99  integrally includes a fan support portion  101 . The fan support portion  101  is a rear extension of the radiation plate  99  traveling in a substantially inclined upward direction. The distal end portion of the fan support portion  101  is located substantially on the same level as the third circuit board  82 . A motor fan  102  is attached to the fan support portion  101 . The motor fan  102  forcibly cools the radiation plate  99 . The motor fan  102  has a fan casing  103  formed of an aluminum alloy. The fan casing  103  is in contact with the fan support portion  101  and serves also as heat sink. 
     If the motor fan  102  is driven, the fan casing  103  and radiation plate  99  are forcibly cooled by air by means of the motor fan  102 , and the heat radiation of the radiation plate  99  is facilitated. As a result, the heat of the TCP  90  transmitted to the cold plate  92  can be efficiently dissipated to the outside via the radiation plate  99 . Since the radiation plate  99  is in contact with the metallic frame  30 , the heat of the TCP  90  transmitted to the radiation plate  99  is dissipated to the frame  30  and naturally radiated via the housing body  2 . Thus, in combination with the forcible air-cooling function of the motor fan  102 , the heat of the TCP  90  can be efficiently radiated. 
     As is shown in FIG. 17, a cooling air passage  105  is defined between the bottom wall  44  of board support portion  32  and the third circuit board  82 . The cooling air passage  105  extends from a central region toward a left-hand end of the board support portion  32 . The aforementioned power supply circuit component  85  is contained within the cooling air passage  105 . The cooling air passage  105  has one end portion communicating with the installation portion of the motor fan  102  and the other end portion reaching the left-hand side wall  5   b  of the lower housing  5 . The side wall  5   b  of the lower housing  5  has a plurality of air holes  106 , as shown in FIG.  16 . The air holes  106  communicate with the cooling air passage  105 . 
     As is shown in FIG. 17, a plurality of cooling fins  107  are formed on the upper surface of the bottom wall  44  facing the cooling air passage  105 . The cooling fins  107  extend in the direction of extension of the cooling air passage  105 . 
     In the above structure, if the motor fan  102  is driven, the cooling air passage  105  is set at a negative pressure level and thus the air outside the housing body  2  is sucked into the cooling air passage  105  via the air holes  106 . The air flows as cooling wind through the cooling air passage  105 , while forcibly cooling the power supply circuit component  85 . The cooling wind flows along the bottom wall  44  receiving heat of the radiation plate  99 , thus facilitating the heat radiation of the bottom wall  44 . In addition, since the bottom wall  44  has the cooling fins  107 , the heat radiation area of the bottom wall  44  increases and the heat of the TCP  90  transmitted from the radiation plate  99  is efficiently radiated. 
     As is shown in FIG. 18, an extension area  110  is provided within the housing body  2 . The extension area  110  is located on the right-hand part of the board support portion  32 . The extension area  110  is divided into a MODEM storage section  111  and a card storage section  112 . The MODEM storage section  111  and card storage section  112  are arranged such that they are stacked on each other in the thickness direction of the housing body  2 . The MODEM storage section  111  stores a MODEM pack (not shown) constructed as a module unit. The MODEM storage section  111  is located above the fourth circuit board  83 . The card storage section  112  removably contains an extension card such as a PCMCIA (Personal Computer Memory Card International Association) or an interface card. The card storage section  112  is located between the first circuit board  60  and the fourth circuit board  83 . The card storage section  112  has a card connector  113  for connection with the extension card and a card guide  114  for guiding the extension card to the card connector  113 . The card connector  113  and card guide  114  are mounted on the first circuit board  60 . 
     As is shown in FIG. 19B, an opening portion  118  communicating with the extension area  110  is formed in the right-hand side wall  5   c  of the lower housing  5 . The opening portion  118  includes a MODEM insertion port  118   a  associated with the MODEM storage section  111  and a card insertion port  118   b  associated with the card storage section  112 . The lower housing  5  is provided with a cover unit  119  of a synthetic resin covering the opening portion  118 . 
     The cover unit  119  has a MODEM cover  120  and a card cover  121 . The MODEM cover  120  has a rectangular plate-like shape with a size corresponding to the MODEM insertion port  118   a . The MODEM cover  120  comprises a pair of stays  122   a  and  122   b  extending downward, and a bracket portion  123  coupling lower end portions of the stays  122   a  and  122   b . The bracket portion  123  of MODEM cover  120  is supported on the bottom wall  5   a  of lower housing  5 . 
     Specifically, as shown in FIG. 19B, the bottom wall  5   a  of lower housing  5 , which faces the opening portion  118 , is provided with a cover attachment portion  125  having a pair of boss portions  124   a  and  124   b . The cover attachment portion  125  faces the card insertion portion  118   b . The bracket portion  123  of MODEM cover  120  is abutted upon the cover attachment portion  125 . Screw holes  126   a  and  126   b  associated with the boss portions  124   a  and  124   b  are formed in the bracket portion  123 . Screws  127  are inserted into the screw holes  126   a  and  126   b . The screws  127  are turned and driven into the boss portions  124   a  and  124   b . Thereby, the MODEM cover  120  is fixed on the lower housing  5 , and the MODEM insertion port  118   a  is covered by the MODEM cover  120 . 
     The card cover  121  has a rectangular plate-like shape with a size corresponding to the card insertion port  118   b . The card cover  121  is supported on the bracket portion  123  of the MODEM cover  120 . The bracket portion  123  has a pair of cover support portions  130   a  and  130   b  which are spaced apart from each other in the depth direction of the lower housing  5 . The card cover  121  is rotatably supported between the cover support portions  130   a  and  130   b . Thus, the card cover  121  is rotatably supported on the bracket portion  123  between a closed position where the card cover  121  is turned up to be substantially flush with the side wall  5   c , and an open position where the card cover  121  is turned down to the right side of the lower housing  5  to expose the card insertion port  118   b . In the state in which the card cover  121  is rotated to the closed position, the card cover  121  is continuous with the MODEM cover  120  and covers the bracket portion  123  of MODEM cover  120  and screws  127  in the lateral direction. 
     According to the cover unit  119  having the above structure, since the card cover  121  is rotatably supported on the MODEM cover  120 , there is no need to provide the lower housing  5  with a support member for supporting the card cover  121 . Thus, the structure of the lower housing  5  is simplified and the number of parts is reduced, as compared to the case where the MODEM cover  120  and card cover  121  are individually attached to the lower housing  5 . 
     Furthermore, the fixing portion of the MODEM cover  120  and lower housing  5  can be covered by using the card cover  121 , and there is no need to provide special parts for covering the bracket portion  123  or screws  127 . 
     As is shown in FIG. 20, an FDD connector  136  is mounted on the lower surface of the first circuit board  60 . The FDD connector  136  is used for connection with an external floppy disk drive  135 . The FDD connector  136  is located in a lower region of the second section  39  of pack storage section  31  and is adjacent to a corner portion defined by the bottom wall  5   a  and right-hand side wall  5   c  of lower housing  5 . The lower housing S has a connector lead-out port  137  facing the FDD connector  136 . As shown in FIG. 21A, the connector lead-out port  137  is open in a space from the bottom wall  5   a  to side wall  5   c  of the lower housing  5 . A cover storage section  138  having a recess shape is formed in the bottom wall  5   a  and side wall  5   c  of the lower housing  5 . The cover storage section  138  is continuous with the front end of the connector lead-out port  137 . 
     The connector lead-out port  137  has a first opening edge portion  140  and a second opening edge portion  141 . The first opening edge portion  140  extends in the depth direction of the lower housing  5  on the bottom wall  5   a . The second opening edge portion  141  extends in the depth direction of the lower housing  5  on the side wall  5   c . A guide groove  142  is formed in the side wall  5   c  along the second opening edge portion  141 . The opening edge portions  140  and  141  and guide groove  142  extend to the region of the cover storage section  138 . 
     A connector cover  145  for opening/closing the connector lead-out port  137  is attached to the lower housing  5 . The connector cover  145  comprises a bottom plate portion  146  continuous with the bottom wall  5   a  and a side plate portion  147  continuous with the side wall  5   c . The bottom plate portion  146  has an engaging portion  148  slidably engaged with the first opening edge portion  140 . An inwardly projecting engaging portion  149  is formed on an upper end portion of the side plate portion  147 . The engaging portion  149  is slidably engaged with the guide groove  142  in the side wall  5   c.    
     A plate-like cover holder  150  is fixed on the inner surface of the bottom wall  5   a , as shown in FIGS. 21A to  21 C. The cover holder  150  is disposed along the first opening edge portion  140  of the connector lead-out port  137 , and one side portion of the cover holder  150  projects inside the connector lead-out port  137 . A guide groove  152  is formed in the lower surface of said one side portion of the cover holder  150 . The guide groove  152  extends along the first opening edge portion  140 , and the engaging portion  148  of the bottom plate portion  146  is slidably engaged in the guide groove  152 . By this engagement, the engaging portion  148  is irremovably held on the first opening edge portion  140  and the connector cover  145  is not displaced to the laterial side. 
     The connector cover  145  is slidably held on the lower housing  5  by guide means comprising engagement portions between the engaging portion  148  and guide groove  152  and between the engaging portion  149  and guide groove  142 . Thus, as shown in FIGS. 21B and 21C, the connector cover  145  is slidable between a closed position where the connector lead-out port  137  is closed and an open position where the connector lead-out port  137  is opened. In the state in which the connector cover  145  is slid to the opening position, the connector cover  145  is stored in the cover storage portion  138 . 
     As is shown in FIGS. 21B and 21C, a pair of positioning projections  153   a  and  153   b  are provided on one side portion of the guide groove  152 . The positioning projections  153   a  and  153   b  are spaced apart from each other in the direction of sliding movement of the connector cover  145 . One of the position projections, i.e. projection  153   a , is disposed in a position associated with the closed position of the connector cover  145 , and the other positioning projection  153   b  is disposed in a position associated with the open position of the connector cover  145 . An engaging projection  154  is provided on one end portion of the engaging portion  148  of connector cover  145 . The engaging projection  154  is put in slidable contact with said one side portion of the guide groove  152 . 
     When the connector cover  145  is slid from the open position to the closed position, the engaging projection  154  moves beyond the the positioning projection  153   a  just before the connector cover  145  reaches the closed position. At this time, the operator feels a click. Similarly, when the connector cover  145  is slid from the closed position to the open position, the engaging projection  154  moves beyond the the other positioning projection  153   b  just before the connector cover  145  reaches the open position. At this time, the operator feels a click. Accordingly, the operator can recognize that the connector cover  145  has reached the closed position or open position, and the sliding operation of the connector cover  145  is ensured. 
     As is shown in FIGS. 8 and 22, a first relay connector  160  is disposed in the first section  38  of the pack storage section  31 . The first relay connector  160  is located at the terminal end portion of the first section  38  and opposed to the insertion hole  40  of the first section  38 . The terminal end portion of the first section  38  is constituted by the rear wall  35  of the pack storage section  31 . A connector attachment portion  161  is formed on the rear wall  35 . The connector attachment portion  161  has a groove shape and is opened upward of the pack storage section  31 . 
     A second relay connector  164  is disposed in the second section  39  of the pack storage section  31 . The second relay connector  164  is located at the terminal end portion of the second section  39  and opposed to the insertion hole  41  of the second section  39 . The terminal end portion of the second section  39  is constituted by the rear wall  35  of the pack storage section  31 . A connector attachment portion  165  is formed on the rear wall  35 . The connector attachment portion  165  has a groove shape and is opened upward of the pack storage section  31 . 
     The first relay connector  160  and second relay connector  164  are mounted on a flexible wiring board  170  with reinforcement plates  168  and  169  interposed. A first stacking connector  172  is mounted on a middle portion of the wiring board  170  with use of a reinforcement plate  171 . The wiring board  170  has an extension part  173  continuous with the mounting portion of the first relay connector  160 . A second stacking connector  175  is mounted on a distal end portion of the extension part  173  with use of a reinforcement plate  174 . Thus, the first relay connector  160 , second relay connector  174 , first stacking connector  172  and second stacking connector  175  are integrated by the wiring board  170 . 
     The wiring board  170  is disposed on the upper surface of the bottom wall  33  of the pack storage section  31 . The bottom wall  33  has an opening portion  177  facing the stacking connector  172 . The stacking connector  172  is connected to the first circuit board  60  via the opening portion  177 . 
     As is shown in FIGS. 17 and 22, a first connector holder  180  of a synthetic resin is attached to the reinforcement plate  168  of first relay connector  160 . The first connector holder  180 , along with the reinforcement plate  168 , is tightly fitted in the connector attachment portion  161  from the above region of the frame  30 . Thereby, the first relay connector  160  is held on the terminal end portion of the first section  38 . 
     As is shown in FIGS. 22 and 30A, the second relay connector  164  is mounted in the connector attachment portion  165  with use of a second connector holder  181  of a synthetic resin. Specifically, the second connector holder  181  is superposed on the reinforcement plate  169  and, in this state, tightly fitted into the connector attachment portion  165  from the above region of the frame  30 . Thereby, the second relay connector  164  is held on the terminal end portion of the second section  39 . 
     The extension part  173  of the wiring board  170  is led to the upper region of the board support portion  32  from the terminal end portion of the first section  38 , and the second stacking connector  175  is connected to the second circuit board  81 . 
     According to the above structure, the first and second relay connectors  160  and  164  are held in the pack storage section  31  of frame  30  by the tight-fitting method. There is no need to perform time-consuming works such as fixing the relay connectors  160  and  164  on the first circuit board  60  by means of screws or soldering. The assembling work of the computer  1  is improved. 
     As is shown in FIG. 23, one of a CD-ROM drive  190  and a floppy disk drive (FDD)  191  is detachably mounted, as a pack-type device, in the first section  38  of pack storage section  31  in a selective manner. The CD-ROM drive  190  and FDD  191  are constructed as module packs having individual functions and have the same size. 
     The CD-ROM drive  190 , as shown in FIGS. 24 and 25, comprises a tray  192  for receiving an optical disk, and a metallic cabinet  193  for holding the tray  192  such that the tray  192  can be pulled out. The cabinet  193  has a flat box-like shape. An interface connector  194  is disposed on an end portion of the cabinet  193 , which is located opposite to the tray  192 . The interface connector  194  is mounted on one end portion of a flexible wiring board  196  with a reinforcement plate  195  interposed. The other end portion of the wiring board  196  is detachably connected to a control circuit unit provided inside the cabinet  193  via a connector (not shown). The reinforcement plate  195  has first and second end portions projecting outward of the interface connector  194 . The end portions of the reinforcement plate  195  have through-holes  197  respectively. 
     A connector hold frame  198  formed of a metallic plate is attached to the cabinet  193 . The connector hold frame  198  integrally comprises a pair of support stays  199   a  and  199   b  attached by screws on the side faces of the cabinet  193 , and a hold plate  200  for coupling the support stays  199   a  and  199   b  to each other. The hold plate  200  includes an opening portion  201 , through which the interface connector  194  is passed, a pair of through-holes  202   a  and  202   b  communicating with the through-holes  197   a  and  197   b  in the reinforcement plate  196 , and a pair of engaging holes  203   a  and  203   b  located outside of the through-holes  202   a  and  202   b . The hold plate  200  is superposed on the reinforcement plate  195 . 
     Referring to FIGS. 25 and 26, a connector holder  205  of a synthetic resin is interposed between the reinforcement plate  195  and cabinet  193 . The connector holder  205  integrally comprises a flat support face  206  overlapping the reinforcement plate  195 , and a pair of flat seat portions  207   a  and  207   b  continuous with the support face  206 . A pair of nuts  209  are buried in the support face  206 . The nuts  209  face the through-holes  197  in the reinforcement plate  196 . The seat portions  207   a  and  207   b  have engaging projections  210  respectively. The engaging projections  210  are engaged in the associated engaging holes  203   a  and  203   b  in the hold plate  200 , thereby positioning the connector holder  205  and hold plate  200 . 
     The hold plate  200  and connector holder  205  are covered by an outer cover  211  of a synthetic resin. The outer cover  211  has a panel portion  211   a  overlapping the hold plate  200 . The panel portion  211   a  has a connector lead-out port  212  for leading out the interface connector  194 , and a pair of screw holes  213   a  and  213   b  communicating with the through-holes  202   a  and  202   b  in the hold plate  200 . Screws  215  are inserted into the screw holes  213   a  and  213   b . The screws  215  are driven into the nuts  209  through the through-holes  202   a  and  202   b  and the through-holes  197 . Thereby, the connector holder  205  and reinforcement plate  195  are clamped between the hold plate  200  of the connector hold frame  198  and the cabinet  193  and the interface connector  194  is irremovably held on the cabinet  193 . 
     As is shown in FIGS. 24 and 25, the support stays  199   a  and  199   b  of connector hold frame  198  have engaging portions  216   a  and  216   b . The engaging portions  216   a  and  216   b  protrude laterally from side surfaces of the cabinet  193  at a draw-out-side end portion of the tray  192  of cabinet  193 . 
     The CD-ROM drive  190  is inserted into the first section  38  through the front-end insertion hole  40  of the lower housing  5 . While the CD-ROM drive  190  is being inserted into the first section  38 , the outer cover  211  and cabinet  193  are guided by the inner faces of the first section  38 , thus aligning the interface connector  194  and first relay connector  160 . In the state in which the interface connector  194  is connected to the first relay connector  160 , the front face of the tray  192  is located at the opening portion of the insertion hole  40  so as to be continuous with battery cover  27 . 
     The FDD  191 , as shown in FIGS. 23 and 27, comprises a flat box-shaped floppy disk drive (FDD) body  220  having a floppy disk insertion hole  219 , and an outer cover  221  of a synthetic resin covering the FDD body  220 . The outer cover  221  has substantially the same shape and size as the cabinet  193  of the CD-ROM drive  190 . The outer cover  221  has a connector attachment portion  222  at an end portion thereof opposed to the floppy disk insertion hole  219 . An interface connector  223  is disposed on the connector attachment portion  222 . 
     As is shown in FIG. 28, the outer cover  221  comprises an upper cover  225  and a lower cover  226 . The connector attachment portion  222  has an outer wall  227  extending downward from the upper cover  225  and an inner wall  228  extending upward from the lower cover  226 . The outer wall  227  and inner wall  228  face each other at a predetermined distance therebetween, as shown in FIGS. 29A and 29B. The outer wall  227  and inner wall  228  have elongated notches  229  and  230  facing each other. The notches  229  and  230  define a connector lead-out port  231  in an end face of the connector attachment portion  222 . 
     As is shown in FIGS. 28 and 29B, the interface connector  223  is mounted on an elongated circuit board  233 . The circuit board  233  is connected to the internal control circuit section in the FDD body  220  via a flexible wiring board  234 . The circuit board  233  has first and second end portions projecting outward of the interface connector  223 . The end portions of the circuit board  233  have through-holes  235  and engaging holes  236  respectively. 
     The first and second end portions of the circuit board  233  are clamped between the outer wall  227  and inner wall  228 . Portions of the inner wall  228 , which face the first and second end portions, have nuts  238  and engaging projections  239  respectively. The nuts  238  are buried in the inner wall  228  and face the through-holes  235  in the circuit board  233 . The engaging projections  239  are located near the nuts  238 . The engaging projections  239  are fitted in the engaging holes  236  in the circuit board  233 , and thereby the circuit board  233  and lower cover  226  are positioned. An engaging groove  240  opening to the connector lead-out port  231  is formed in the lower cover  226 , and a lower edge portion of the circuit board  233  is fitted in the engaging groove  240 . 
     As is shown in FIG. 28, a pair of screw holes  241  are formed in the outer wall  227  of the upper cover  225 . The screw holes  241  communicate with the through-holes  235  in the circuit board  233 . Screws  242  are passed through the screw holes  241 . The screws  242  are driven into the nuts  238  through the through-holes  235  in the circuit board  233 , as shown in FIG.  29 B. Thereby, the circuit board  233  are clamped between the outer wall  227  and inner wall  228  and the interface connector  223  is irremovably held on the connector attachment portion  222 . 
     The lower cover  226  has a pair of engaging portions  243   a  and  243   b , as shown in FIG.  27 . The engaging portions  243   a  and  243   b  protrude laterally from side surfaces of the FDD body  220  at the floppy disk insertion hole ( 219 ) side end portion of the body  220 . 
     The floppy disk drive (FDD)  191  is inserted into the first section  38  through the front-end insertion hole  40  of the lower housing  5 . While the FDD  191  is being inserted into the first section  38 , the outer cover  221  is guided by the inner faces of the first section  38 , thus aligning the interface connector  223  and first relay connector  160 . In the state in which the interface connector  223  is connected to the first relay connector  160 , the floppy disk insertion hole  219  is located at the opening portion of the insertion hole  40 . 
     As is shown in FIGS. 4 and 30A, a hard disk drive (HDD)  250  is removably mounted in the second section  39  of the pack storage section  31 . The HDD  250  has a flat housing  251  containing a magnetic head, a disk-shaped magnetic recording medium, etc., though these are not shown. An HDD connector  252  is disposed at one end portion of the housing  251 . The HDD  250  is inserted into the second section  39  from the insertion hole  41  in the front end portion of the lower housing  5 . Thereby, the HDD connector  252  is connected to the second relay connector  164 . 
     As is shown in FIGS. 3 and 30A, a front cover  255  of a synthetic resin is attached to the front end portion of the lower housing  5 . The front cover  255  comprises a bottom wall portion  256 , a front wall portion  257  continuous with the bottom wall portion  256 , and a side wall portion  258  continuous with the bottom wall portion  256  and front wall portion  257 . The bottom wall portion  256  and front wall portion  257  extend in the width direction of the lower housing  5 . The side wall portion  258  is located at the right-hand end portions of the bottom wall portion  256  and front wall portion  257 . 
     As is shown in FIGS. 2 and 10, the bottom wall portion  256  of front cover  255  has three boss portions  260 . The boss portions  260  project from an edge of the bottom wall portion  256  and are arranged at intervals in the width direction of the lower housing  5 . Three recess portions  261  are formed in a front end portion of the bottom wall  5   a  of the lower housing  5 . The recess portions  261  are arranged at intervals in the width direction of the lower housing  5 . The boss portions  260  are put in the recess portions  261 . The boss portions  260  are rotatably coupled to the recess portions  261  by means of pins  262  extending in the width direction of the lower housing  5 . 
     Thus, the front cover  255  is supported on the lower housing  5  rotatably between a first position where the front wall portion  257  thereof faces the insertion holes  40  and  41  of the pack storage section  31  and a second position where the front wall portion  257  is turned down in front of the insertion holes  40  and  41 . When the front cover  255  is rotated to the first position, the bottom wall portion  256  is continuous with the bottom wall  5   a  of lower housing  5  and the side wall portion  258  is continuous with the right-hand side wall  5   c  of lower housing  5 . 
     As is shown in FIG. 3, the front wall portion  257  of the front cover  255  has a rectangular notched opening portion  263 . The opening portion  263  extends in the width direction of lower housing  5 . The opening portion  263  has a size corresponding to the front face of each of the CD-ROM drive  190  and FDD  191 . Even in the state in which the front cover  255  is rotated to the first position, the tray  192  of the CD-ROM drive  190  or the floppy disk insertion hole  219  of the FDD  191  is exposed to the front of the housing body  2  through the opening portion  263 . 
     As is shown in FIG. 10, gaps S extending in the width direction of the lower housing  5  are defined between the boss portions  260  of front cover  255  and the recess portions  261  of lower housing  5 . By virtue of the gaps S, when the front cover  255  is rotated to the first position, the front cover  255  is supported on the lower housing  5  slidably between a locked position where the side wall-portion  258  is continuous with the right-hand side wall  5   c  of lower housing  5  and an unlocked position where the side wall portion  258  is displaced to the right side from the side wall  5   c.    
     As is shown in FIGS. 9,  10  and  23 , a first engaging projection  265   a  and a second engaging projection  265   b  are formed on the inner surface of the front wall portion  257  of front cover  255 . The first and second engaging projections  265   a  and  265   b  are spaced apart in the width direction of the lower housing  5  in a position adjacent to the opening edge of the opening portion  263 . In addition, a third engaging projection  265   c  is formed on an edge portion of the side wall portion  258 . 
     When the front cover  255  is slid to the locked position, the first engaging projection  265   a  is disengageably engaged with the front end portion of the bottom wall  5   a , as shown in FIG.  34 A. When the front cover  255  is slid to the locked position, the second and third engaging projections  265   b  and  265   c  advance to the front end portion of the partition wall  37  of pack storage section  31  and the front end portion of the right-hand side wall  34   b , as shown in FIGS. 35A and 36A. The front end portions of the partition wall  37  and side wall  34   b  have engaging holes  266   a  and  266   b  in which the second and third engaging projections  265   b  and  265   c  are disengageably engaged. 
     As is clear from FIG. 33A, if the front cover  255  is rotated to the first position and then slid to the locked position, the first to third engaging projections  265   a  to  265   c  engage the front edge portion of the bottom wall  5   a  and engaging holes  266   a  and  266   b . Thus, the front cover  255  is held in the first position. When the front cover  255  is held in the first position, the HDD  250  stored in the second section  39  is covered by the front wall portion  257  of front cover  255 . 
     As is shown in FIGS. 1 and 4, a first icon  270  is provided on the front wall portion  257  of front cover  255 . The first icon  270  has a light-transmissive icon board  271 . The icon board  271  has a rectangular shape, extending in the width direction of the lower housing  5 . The icon board  271  is attached to the front face of the front wall portion  257  of front cover  255 . Four display marks  272  relating to the power supply of computer  1  are arranged linearly on the icon board  271 . 
     As is shown in FIGS. 30A and 30B, the front wall portion  257  of front cover  255  has four holes  273  (only one shown) facing the display marks  272 . These holes  273  are located near the front edge portion of the first circuit board  60 . Four light emitting diodes (LEDs)  275  (only one shown) functioning as light source of the first icon  270  are mounted on the lower surface of the front edge portion of the first circuit board  60 . When the front cover  255  is held in the first position, the LEDs  275  face the bottom wall portion  256  of front cover  255 . The LEDs  275  radiate light downward of the first circuit board  60 . 
     As is shown in FIGS. 3,  30 B and  32 , four optical waveguides  276  are attached to the inner surface of the front cover  255 . The optical waveguides  276  guide light from the LEDs  275  to the display marks  272  and are formed of transparent synthetic resin material. Each of the optical waveguides  276  comprises a first waveguide portion  277  extending in the height direction of lower housing  5  along the front wall portion  257  of front cover  255 , and a second waveguide portion  278  extending in the depth direction of lower housing  5  along the bottom wall portion  256  of front cover  255 . The first and second waveguide portions  277  and  278  are formed as one piece. 
     A forwardly bent lens portion  279  is formed at an upper end portion of the first waveguide portion  277 . A distal end portion of the lens portion  279  enters the hole  273  and comes into contact with the rear face of the icon board  271 . As is clear from FIG. 30B, a corner portion defined by the first waveguide portion  277  and lens portion  279  has a first light guide face  280  which is downwardly inclined as it extends rearward. 
     A rear end portion of the second waveguide portion  278  is located below the first circuit board  60 . A light receiving portion  281  is formed on the rear end portion of second waveguide portion  278 . The light receiving portion  281  has a flat light receiving surface  282  opposed to the LED  275 , and a second light guide face  283  opposed to the light receiving surface  282 . The second light guide face  283  is forwardly inclined as it extends away from the light receiving surface  282 . Accordingly, when light is made incident on the light receiving surface  282  from the LED  275 , the light is reflected by the second light guide face  283  and then guided through the second waveguide portion  277 . 
     A third light guide face  284  is formed on a corner portion defined by the first and second waveguide portions  277  and  278 . The third light guide face  284  is downwardly inclined as it extends rearwards. The third light guide face  284  is located in front of the second light guide face  283 . The third light guide face  284  reflects the light, which has been guided from the second light guide face  283 , upward to the first light guide face  280 . Thus, as is indicated by the arrow in FIG. 30B, light radiated downward from the LED  275  is made incident on the light receiving surface  282  of optical waveguide  276  and it is reflected successively by the second light guide face  283 , third light guide face  284 , and first light guide face  280 . The light reflected by the first light guide face  280  reaches the lens portion  279 . Accordingly, the display mark  272  associated with the LED  275  which is emitting light is lighted up to effect display relating to the power supply. 
     As is shown in FIGS. 23 and 31, when the front cover  255  is rotated to the second position, the optical waveguide  276  is rotated forwardly along with the front cover  255  and is exposed to the front side of the lower housing  5 . At this time, the light receiving portion  281  of optical waveguide  276  moves downward away from the LED  275 . 
     The first section  38  has a stopper  290 , as shown in FIGS. 10,  23  and  39 , which is engaged with the CD-ROM drive  190  or floppy disk drive (FDD)  191 . As is clear from FIGS. 37 and 41, the stopper  290  is disposed on a front end portion of the bottom wall  5   a  of lower housing  5 . When the CD-ROM drive  190  or FDD  191  is mounted in the first section  38 , the stopper  290  is located immediately in front of the engaging portion  216   a  or  243   a  thereof. 
     As is shown in FIGS. 38A to  38 C, the stopper  290  is supported on the bottom wall  5   a  so as to be vertically movable between a locked position where the stopper  290  projects into the first section  38  and engages the front face of the engaging portion  216   a  or  243   a , and an unlocked position where the stopper is pulled down from the first section  38  and disengaged from the front face of the engaging portion  216   a  or  243   a . The stopper  290  is always urged by a spring  291  toward the unlocked position. 
     As is shown in FIG. 37, the stopper  290  has a pressing surface  292  exposed downward of the bottom wall  5   a  of lower housing  5 . When the front cover  255  is rotated to the first position, the pressing surface  292  is opposed to the bottom wall portion  256  of front cover  255 . The bottom wall portion  256  has a pressing projection  293 . When the front cover  255  is rotated from the second position to the first position, the pressing projection  293  contacts the pressing surface  292  of stopper  290  and pushes up the stopper  290  from the unlocked position to the locked position. Accordingly, in the state in which the front cover  255  is held in the first position, the stopper  290  engages the engaging portion  216   a  of CD-ROM drive  190  or the engaging portion  243   a  of FDD  191 , thereby locking the CD-ROM drive  190  or FDD  191  in the first section  38 . 
     As is shown in FIGS. 37 and 38A to  38 C, a slider  295  for pushing the front cover  255  to the locked position is attached to the front end portion of the bottom wall  5   a  of lower housing  5 . The slider  295  is supported on the bottom wall  5   a  slidably between a first position where the slider  295  adjoins the stopper  290  on the right side of the stopper  290 , and a second position where the slider  295  is located away from the stopper  290 . The slider  295  is always urged to the first position by a return spring  296 , and a distal end portion thereof is always adjoins or contacts the side face of the stopper  290 . 
     The slider  295  has an inclined surface  297  at a lower portion of its distal end portion facing the stopper  290 . The inclined surface  297  is gradually inclined upward as it extends towards the stopper  290 . When the front cover  255  is rotated to the first position, the inclined surface  297  contacts a corner portion of the pressing projection  293 . The corner portion of pressing projection  293  has a beveled surface  298 . The beveled surface  298  is inclined in the same direction as the inclined surface  297  of slider  295 . The beveled surface  298  slidably contacts the inclined surface  297 . 
     When the front cover  255  is rotated from the second position to the first position, as shown in FIG. 38B, the beveled surface  298  of pressing projection  293  is put in contact with the inclined surface  297  of the slider  295 . Thereby, the slider  295  is slid from the first position to the second position against the urging force of the return spring  296 . When the front cover  255  has reached the first position, the first to third engaging projections  265   a  to  265   c  face the front end portion of the bottom wall  5   a  and engaging holes  266   a  and  266   b , and the beveled surface  298  of pressing projection  293  passes over the inclined surface  297  of slider  295 . Since the slider  295  is urged toward the first position by the return spring  296 , the urging force is transmitted to the front cover  255  via the pressing projection  293 , and the front cover  255  is forcibly slid from the unlocked position to the locked position. As a result, as shown in FIGS. 34A,  35 A and  36 A, the first engaging projection  265   a  engages the front end portion of the bottom wall  5   a , and the second and third engaging projections  265   b  and  265   c  engage the engaging holes  266   a  and  266   b  in the frame  30 . Thus, the front cover  255  is held in the first position. 
     As is shown in FIG. 23, an ejector  300  is disposed in the insertion hole  40  of the first section  38 . The ejector  300  is used to discharge the CD-ROM drive  190  or FDD  191  from the first section  38 . The ejector  300  has a slider  301  and an operation lever  302 , as shown in FIGS. 39 to  41 . The slider  301  has a flat plate shape, extending in the width direction of the first section  38 . The slider  301  is supported on the bottom wall  33  of frame  30  by means of a pair of pins  303  and is slidable in the depth direction of the first section  38 . The slider  301  has a pair of upwardly extending pushing portions  304   a  and  304   b . When the CD-ROM drive  190  or FDD  191  is inserted into the first section  38 , the pushing portions  304   a  and  304   b  face the rear faces of the engaging portions  216   a  and  216   b  of CD-ROM drive  190  or the engaging portions  243   a  and  243   b  of FDD  191 . 
     The operation lever  302  is supported on the upper surface of the slider  301  by means of a pair of pins  305  and is slidable in the depth direction of the first section  38 . A front end portion of the operation lever  302  projects forward of the slider  301 . The front end portion of the operation lever  302  is provided with a downwardly bent finder hook portion  306 . The finger hook portion  306  is located at the opening end of the insertion hole  40 . In the state in which the front cover  255  is held in the first position, the front side of the finger hook portion  306  is covered by the front wall portion  257  of front cover  255 . 
     Accordingly, if the front cover  255  is rotated to the second position, as shown in FIG. 40, the finger hook portion  306  of ejector  300  is exposed to the insertion hole  40  of first section  38 . If the finger hook portion  306  is hooked by the finger and the operation lever  302  is pulled out, the slider  301  is drawn out accordingly. The pushing portions  304   a  and  304   b  of slider  301  push the engaging portions  216   a  and  216   b  of CD-ROM drive  190  or the engaging portions  243   a  and  243   b  of FDD  191  towards the insertion hole  40 . Thereby, the CD-ROM drive  190  or FDD  191  is pushed out of the insertion hole  40 , and the first relay connector  160  is disconnected from the interface connector  194  or  223 . 
     As is shown in FIGS. 30A and 44, the upper housing  6  of housing body  2  covers the upper side of the frame  30 . A keyboard support section  310  is formed in a central region of the upper wall  6   a  of upper housing  6 . The keyboard support section  310  comprises a rectangular recess extending over substantially the entire central region of the upper wall  6   a . The keyboard support section  310 , as shown in FIGS. 30A and 47, has a peripheral wall  311  extending downward from the upper wall  6   a  and a bottom wall  311   a  continuous with the lower end of the peripheral wall  311 . The bottom wall  311   a  is formed at corner portions of the keyboard support section  310 . Most part of the keyboard support section  310  is open to the inside of the lower housing  5 . A metallic shield plate  312  is attached to the inner surface of the upper wall  6   a  of upper housing  6 , as shown in FIG.  30 A. The shield plate  312  covers the bottom side of the keyboard support section  310 . 
     A keyboard  313  serving as information input means is removably attached to the keyboard support section  310 . The keyboard  313  comprises a support panel  314  of a synthetic resin, a number of keys  315 , and a joystick  316  or a kind of pointing device. The support panel  314  has a rectangular plate shape with such a size as to be fittable in the keyboard support section  310 . The keys  315  and joystick  316  are disposed on the upper surface of the support panel  314 . The lower surface of the support panel  314  is covered by a metallic reinforcement plate  317 . 
     The support panel  314  of keyboard  313  has a front edge portion and a rear edge portion both extending in the width direction of the housing body  2 . The front edge portion and rear edge portion of support panel  314  are detachably hooked on the peripheral wall  311  of keyboard support section  310 . Thus, the keyboard  313  is supported on the keyboard support section  310 . In the state in which the keyboard  313  is attached to the keyboard support section  310 , the reinforcement plate  317  is in contact with the shield plate  312 . The contact between the reinforcement plate  317  and shield plate  312  prevents switching noise due to key operations from entering the inside of the housing body  2 . 
     A front half portion of the upper wall  6   a  of upper housing  6  constitutes an armrest  320 . Click switch buttons  321   a  and  321   b  for executing and canceling commands are disposed on a central portion of the armrest  320 . 
     As is shown in FIGS. 44 to  46 , a component attachment portion  323  is formed integral with the rear part of the upper housing  6  continuous with the keyboard support section  310 . The component attachment portion  323  has a plate shape, extending in the width direction of upper housing  6 . The width of the component attachment portion  323  is substantially equal to that of the upper housing  6 . The component attachment portion  323  is situated above the board support portion  32  of frame  30 . The first circuit board  81  and fourth circuit board  83  are located just below the component attachment portion  323 . As is shown in FIGS. 17 and 44, a notch  323   a  formed at a rear end portion of the component attachment portion  323 . The notch  323   a  is provided to avoid the motor fan  102 . The motor fan  102  projects from the notch  323   a.    
     Referring to FIGS. 42,  43 A and  43 B, the display unit  3  is supported by the upper housing  6 . The display unit  3  comprises a display housing  325  of a flat box shape, and a color liquid crystal display (LCD)  326  contained in the display housing  325 . The display housing  325  includes first and second leg portions  327   a  and  327   b  functioning as support portions. The leg portions  327   a  and  327   b , as shown in FIGS. 45 and 46, are supported on the component attachment portion  323  by means of first and second hinge metal fixings  328  and  329 . The first and second hinge metal fixings  328  and  329  are spaced apart in the width direction of the component attachment portion  323 . The first hinge metal fixing  328 , as shown in FIGS. 42 and 43A, comprises a hinge shaft  330 , a first bracket  331  fixed to a first end portion of the hinge shaft  330 , and a second bracket  332  rotatably coupled to a second end portion of the hinge shaft  330 . The first end portion of the hinge shaft  330  penetrates a left-hand side face of the first leg portion  327   a  and enters the inside of the leg portion  327   a . The first bracket  331  provided at the first end portion of the hinge shaft  330  is screwed down on the inner surface of leg portion  327   a . The second bracket  332  provided at the second end portion of hinge shaft  330  is located at the left-hand end portion of the component attachment portion  323 . 
     The second bracket  332  has a support stay  333  as integral portion. The support stay  333  extends below the component attachment portion  323  in the depth direction of the component attachment portion  323 . The component attachment portion  323  has a pair of downwardly projecting boss portions  334   a  and  334   b . The boss portions  334   a  and  334   b  face the support stay  333 . The support stay  333  is fixed by means of screws  335  to the boss portions  334   a  and  334   b . Thus, the left-hand end portion of the component attachment portion  323  is reinforced by the support stay  333 . 
     As is shown in FIG. 48, the support stay  333  is placed on the second circuit board  81 . The board support portion  32  of frame  30 , which supports the second circuit board  81 , has a first hinge receiving portion  336  for receiving the second circuit board  81  and support stay  333 . The first hinge receiving portion  336  faces the bottom wall  5   a  of lower housing  5 . The bottom wall  5   a  has a pair of boss portions  337   a  and  337   b  for supporting the first hinge receiving portion  336 . One of the boss portions,  337   a , is a hollow cylindrical shape opening to the bottom wall  5   a . A screw  338  is passed upward through the boss portion  337   a . The screw  338  is passed through the first hinge receiving portion  336  and second circuit board  81  and is driven in the support stay  333 . A screw  339  is driven into the other boss portion  337   b  from above the component attachment portion  323 . Specifically, the screw  339  is driven into the boss portion  337   b  through the component attachment portion  323 , support stay  333  and second circuit board  81 . Thus, the component attachment portion  323 , first hinge receiving portion  336  of frame  30 , support stay  333  and lower housing  5  are stacked and coupled integrally, and the first hinge metal fixing  328  is received by the rigid frame  30 . 
     As is shown in FIGS. 42 and 43B, the second hinge metal fixing  329  comprises a hinge shaft  340 , a first bracket  341  fixed to a first end portion of the hinge shaft  340 , and a second bracket  342  rotatably coupled to a second end portion of the hinge shaft  340 . The first end portion of the hinge shaft  340  penetrates a right-hand side face of the second leg portion  327   b  and enters the inside of the leg portion  327   b . The first bracket  341  provided at the first end portion of the hinge shaft  340  is screwed down on the inner surface of leg portion  327   b . The second bracket  342  provided at the second end portion of hinge shaft  340  is screwed down on the right-hand end portion of the component attachment portion  323 . 
     As is shown in FIG. 49, the second bracket  342  has a support stay  343  as integral portion. The support stay  343  extends below the right-hand end portion of component attachment portion  323  towards the keyboard support section  310 . A distal end portion of the support stay  343  is located below the right-hand end portion of the keyboard support section  310 . A boss portion  344  is provided on the lower surface of the keyboard support section  310 . The boss portion  344  receives the distal end portion of support stay  343 . The distal end portion of the support stay  343  is fixed to the boss portion  344  by means of a screw  345 . Thus, the right-hand end portion of the component attachment portion  323  and the right-hand end portion of the keyboard support section  310  are reinforced by the support stay  343 . 
     The support stay  343  is located at the right-hand end portion of the board support portion  32  of frame  30 . The board support portion  32  has a second hinge receiving portion  380  for receiving the support stay  343 . The second hinge receiving portion  380  faces the bottom wall  5   a  of lower housing  5 . The bottom wall  5   a  has a pair of boss portions  381   a  and  381   b  for supporting the second hinge receiving portion  380 . Each of the boss portions  381   a  and  381   b  has a hollow cylindrical shape, opening to the bottom wall  5   a  of lower housing  5  near the card insertion hole  118   b . Screws  382  are inserted into the boss portions  381   a  and  381   b  from below. The screws  382  are penetrated through the second hinge receiving portion  380  and driven into the support stay  343 . Accordingly, the second hinge metal fixing  329  is received by the rigid metal frame  30 . 
     Thus, the display unit  3  is supported on the housing body  2  so as to be rotatable about the hinge shafts  330  and  340  among a first position where the display unit  3  covers the upper housing  6  and keyboard  313 , a second position where the display unit  3  is erected in rear of the keyboard  313 , and a third position where the display unit  3  is turned down substantially horizontal towards the rear of the housing body  2 . 
     As is shown in FIGS. 42 to  47 , the component attachment portion  323  has first and second cover portions  346   a  and  346   b . The cover portions  346   a  and  346   b  are disposed on the rear end portion of the component attachment portion  323  at a distance from each other in the width direction of the upper housing  6 . As is shown in FIGS. 45 and 47, the first cover portion  346   a  is situated below the first leg portion  327   a  of display housing  325 . A downwardly extending extension wall  347  is integrally formed at a rear end portion of the first cover portion  346   a . As is shown in FIG. 2, the extension wall  347  is continuous with the second connector cover  75  of lower housing  5 . The second cover portion  346   b  is situated below the second leg portion  327   b  of display housing  325 . A downwardly extending extension wall  348  is integrally formed at a rear end portion of the second cover portion  346   b . The extension wall  348  is continuous with the first connector cover  74  of lower housing  5 . 
     As is shown in FIGS. 44 to  47 , first and second speaker attachment holes  350   a  and  350   b  and a dial attachment hole  351  are formed in the component attachment portion  323 . The speaker attachment holes  350   a  and  350   b  are located near the first and second cover portions  346   a  and  346   b  and are spaced apart in the width direction of the component attachment portion  323 . As is shown in FIG. 44, the speaker attachment holes  350   a  and  350   b  are arranged on both sides of a center line C extending in the depth direction of the housing body  2  through the center of the housing body  2  in the width direction. The first speaker attachment hole  350   a  is located on the left side of the center line C, and the second speaker attachment hole  350   b  is located on the right side of the center line C. The distance L 1  between the first speaker attachment hole  350   a  and the center line C differs from the distance L 2  between the second speaker attachment hole  350   b  and the center line C. In this embodiment, L 1  is greater than L 2 . The dial attachment hole  351  is located between the speaker attachment holes  350   a  and  350   b.    
     First and second speakers  353   a  and  353   b  are disposed as functional parts in the first and second speaker attachment holes  350   a  and  350   b . As is clear from FIGS. 18 and 47, each of the speakers  353   a  and  353   b  has a disk-shaped speaker frame  354  for supporting a vibration plate (not shown), and a cover  355  for covering the vibration plate. An outer peripheral portion of the speaker frame  354  is detachably fitted in the speaker attachment hole  350   a  ( 350   b ) from the above side of the component attachment portion  323 . Thus, the first and second speakers  353   a  and  353   b  are arranged asymmetrically with respect to the center line C of the housing body  2 . The first speaker  353   a  located on the left side is farther from the center line C than the second speaker  353   b  located on the right side. 
     The first and second speakers  353   a  and  353   b  have lead lines  356 , respectively. The lead lines  356  are led from the component attachment portion  323  into the housing body  2  and are connected to the second circuit board  81  via connectors (not shown) respectively. 
     As is shown in FIGS. 18 and 52, the dial attachment hole  351  faces the fourth circuit board  83 . A rotary type volume switch  360  is mounted on the fourth circuit board  83 . The volume switch  360  comprises a switch body  360   b  having a rotational shaft  360   a , and a volume dial  361  coupled as functional element to the rotational shaft  360   a . The rotational shaft  360   a  is erected in the thickness direction of the housing body  2  on the fourth circuit board  83 . The rotational shaft  360   a  has an end face opposed to the dial attachment hole  351 . An engaging groove  360   c  is formed in the end face. The engaging groove  360   c  has a T shape, as clearly shown in FIGS. 50 and 53, and includes a first groove portion  360   d  extending in the radial direction of the rotational shaft  360   a  through the center of the rotational shaft  360   a , and a second groove portion  360   e  extending in a direction perpendicular to the first groove portion  360   d . The first and second groove portions  360   d  and  360   e  are open to the peripheral surface of the rotational shaft  360   a.    
     The volume dial  361  comprises a disk-like body  361   a  and a shaft portion  361   b  continuous with the body  361   a . The body  361   a  has a greater outside diameter than the dial attachment hole  351 . A flange portion  361   c  is formed on the outer peripheral surface of the body  361   a  so as to project radially outward. The shaft portion  361   b  has an engaging projection  361   d  to be removably engaged in the engaging groove  360   c . The engaging projection  361   d  comprises a first projection portion  361   e  extending in the radial direction of the shaft portion  361   b  through the center of the shaft portion  361   b , and a second projection portion  361   f  extending in a direction perpendicular to the first projection portion  361   e . The first projection portion  361   e  is engaged in the first groove portion  360   d , as shown in FIGS. 50 and 53. The width W 1  of the first projection portion  361   e  is less than the width W 2  of the first groove portion  360   d . The second projection portion  361   f  is engaged in the second groove portion  360   e . The width W 3  of the second projection portion  361   f  is less than the width W 4  of the second groove portion  360   e . Accordingly, when the engaging projection  361   d  is engaged in the engaging groove  360   c , a first gap  362  is created between the first projection portion  361   e  and the first groove portion  360   d  and a second gap  363  is created between the second projection portion  361   f  and the second groove portion  360   e . The volume dial  361  is thus movable relative to the rotational shaft  360   a  in a range defined by the gaps  362  and  363 . The volume dial  361  is situated on the component attachment portion  323 . 
     As is shown in FIG. 44, the component attachment portion  323  is covered by a removable top cover  365  of a synthetic resin. The top cover  365  has a panel  366  facing the component attachment portion  323 . The panel  366  has a flat, rectangular plate shape extending in the width direction of the upper housing  6 . The panel  366  integrally comprises first and second hinge cover portions  367   a  and  367   b  and a central cover portion  368 . The cover portions  367   a ,  367   b  and  368  are located at the rear end of the panel  366 . 
     The first and second hinge cover portions  367   a  and  367   b  cover the hinge shafts  330  and  340  and second brackets  332  and  342  of the first and second hinge metal fixings  328  and  329 . The hinge cover portions  367   a  and  367   b  are spaced apart in the width direction of the panel  366  and are projected upward of the panel  366 . As is shown in FIGS. 13,  48  and  49 , the first and second hinge cover portions  367   a  and  367   b  are fixed to the second brackets  332  and  342  of the first and second hinge metal fixings  328  and  329  by means of screws  364 . 
     The central cover portion  368  covers a cable (not shown) for connecting the housing body  2  and display unit  3 , and covers the motor fan  102 . The central cover portion  368  is located between the first and second hinge cover portions  367   a  and  367   b . The central cover portion  368  projects upward of the panel  366  and extends in the width direction of the panel  366 . As is shown in FIG. 13, the central cover portion  368  is fixed to the board support portion  32  of frame  30  by means of a screw  364 . 
     As is shown in FIG. 44, a first insertion hole  370   a  is defined between the first hinge cover portion  367   a  and the left-hand end portion of the central cover portion  368 . A second insertion hole  370   b  is defined between the second hinge cover portion  367   b  and the right-hand end portion of the central cover portion  368 . The first insertion hole  370   a  is associated with the first leg portion  327   a  of display unit  3 . The first leg portion  327   a  is guided into the first insertion hole  370   a . The first insertion hole  370   a  faces the first cover portion  346   a  of component attachment portion  323 . The first cover portion  346   a  defines the bottom of the first insertion hole  370   a.    
     The second insertion hole  370   b  is associated with the second leg portion  327   b  of display unit  3 . The second leg portion  327   b  is guided into the second insertion hole  370   b . The second insertion hole  370   b  faces the second cover portion  346   b  of component attachment portion  323 . The second cover portion  346   b  defines the bottom of the second insertion hole  370   b.    
     As is shown in FIGS. 2 and 17, the central cover portion  368  of top cover  365  has a rear wall  371  exposed to the rear side of the housing body  2 . The rear wall  371  is continuous with the first to third connector covers  74  to  76  of the lower housing  5 . Air exhaust ports  372  are formed in a central portion of the rear wall  371 . The exhaust ports  372  face the motor fan  102 . A cool air wind, which has cooled the TCP  90 , is exhausted through the exhaust ports  372  to the outside of the housing body  2 . 
     As is shown in FIGS. 44,  47  and  48 , the panel  366  has a front edge portion continuous with the keyboard support section  310 . The front edge portion of panel  366  extends in the width direction of the panel  366 . This front edge portion is integrally provided with a downwardly extending engaging wall  375 . The engaging wall  375  is located between the keyboard support section  310  and component attachment portion  323  and placed on the peripheral wall  311  of keyboard support section  310 . A lower end portion of the engaging wall  375  is engaged with a rear edge portion of the support panel  314  of keyboard  313  and cooperates with the bottom wall  311   a  of keyboard support section  310 , thereby clamping the support panel  314 . Thus, the keyboard  313  is held on the keyboard support section  310 . 
     As is shown in FIGS. 18 and 47, the panel  366  of top cover  365  includes first and second cover attachment portions  400  and  401  having sound producing holes  377   a  and  377   b . The cover attachment portions  400  and  401  are spaced apart in the width direction of the panel  366 . The holes  377   a  and  377   b  of the cover attachment portions  400  and  401  face the speakers  353   a  and  353   b . First and second net-like speaker covers  379   a  and  379   b  are attached to the cover attachment portions  400  and  401 . The speaker covers  379   a  and  379   b  cover the holes  377   a  and  377   b  and first and second speakers  353   a  and  353   b . The speaker covers  379   a  and  379   b  have rectangular plate shapes greater than the opening shapes of the holes  377   a  and  377   b , and extend in the width direction of the top cover  365 . Accordingly, the speaker covers  379   a  and  379   b  cover not only the holes  377   a  and  377   b  but also the cover attachment portions  400  and  401  continuous with the holes  377   a  and  377   b.    
     FIGS. 54A and 54B show the second speaker cover  379   b  representatively. The speaker cover  379   b  has one end provided with a first engaging portion  393   a  and the other end provided with a second engaging portion  393   b . The first engaging portion  393   a  extends in parallel to the speaker cover  379   b . The second engaging portion  393   b  extends downward from the speaker cover  379   b . FIG. 54A shows the second cover attachment portion  401  representatively. The cover attachment portion  401  ( 400 ) has first and second engaging holes  401   a  and  401   b  spaced apart in the width direction of the panel  366 . The hole  377   b  is located between the engaging holes  401   a  and  401   b.    
     When the speaker cover  379   b  ( 379   a ) is attached to the cover attachment portion  401  ( 400 ), the first engaging portion  393   a  of the speaker cover  379   b  ( 379   a ) is inserted in the first engaging hole  401   a  from the upper side of the cover attachment portion  401  ( 400 ). Then, the second engaging portion  393   b  is inserted in the second engaging hole  401   b  from the upper side of the cover attachment portion  401  ( 400 ) and a distal end portion of the second engaging portion  393   b  is projected downward from the cover attachment portion  401  ( 400 ). The distal end portion of the second engaging portion  393   b  is then bent along the shape of the cover attachment portion  401  ( 400 ), as shown in FIG. 54B, and the second engaging portion  393   b  is hooked in the second engaging hole  401   b . Thereby, the speaker covers  379   a  and  379   b  are supported on the panel  366 , while covering the cover attachment portions  400  and  401 . 
     As is shown in FIGS. 54A and 54B, a blind member  403  is interposed between the cover attachment portion  401  ( 400 ) and the speaker cover  379   b  ( 379   a ). The blind member  403  prevents the speaker  353   b  ( 353   a ) from being viewed through the speaker cover  379   b  ( 379   a ). The blind member  403  is formed of black felt in a rectangular shape with a size corresponding to the speaker cover  379   b  ( 379   a ). The blind member  403  is attached to the cover attachment portion  401  ( 400 ) by means of a double-sided adhesive tape  404 . 
     As is shown in FIG. 1, the first and second speaker covers  379   a  and  379   b  are arranged on both sides of the center line C of the housing body  2 . A distance L 3  between the first speaker cover  379   a  and the center line C is equal to a distance L 4  between the second speaker cover  379   b  and the center line C. The first and second speaker covers  379   a  and  379   b  are arranged symmetrical with respect to the center line C. As a result, although the first and second speakers  353   a  and  353   b  are actually arranged asymmetrical with respect to the center line C of the housing body  2 , as described above, the first and second speakers  353   a  and  353   b  may be apparently viewed as being symmetrical with respect to the center line C. 
     The panel  366  of top cover  365 , as shown in FIG. 44, has a circular dial lead-out hole  378 . The dial lead-out hole  378  is located between the first and second cover attachment portions  400  and  401 . As is shown in FIGS. 18 and 52, the dial lead-out hole  378  faces the dial attachment hole  351  in the component attachment portion  323 . The dial lead-out hole  378  has a greater diameter greater than the body  361   a  of volume dial  361 . Thus, the body  361   a  of volume dial  361  is exposed upward of the housing body  2  through the dial lead-out hole  378  so that the volume dial  361  may be operated by the fingertip. An annular gap  405  is provided between the body  361   a  and the opening edge portion of the dial lead-out hole  378 . 
     The diameter of the flange portion  361   c  of volume dial  361  is greater than that of the dial lead-out hole  378 . The flange portion  361   c  cover, from the inside of the top cover  365 , the gap  405  between the body  361   a  and dial lead-out hole  378 . The panel  366  of top cover  365  and the flange portion  361   c  overlap each other. The panel  366  cooperates with the component attachment portion  323  to clamp the flange portion  361   c . Thereby, the volume switch  360  is prevented from being pulled out of the switch body  360   b . As is shown in FIG. 52, the panel  366  of top cover  365  has a guide wall  406 . The guide wall  406  has an annular shape and is coaxial with the dial lead-out hole  378 . The guide wall  406  surrounds the flange portion  361   c  of volume dial  361 . Thus, the guide wall  406  positions the volume dial  361  in its radial direction and rotational direction. 
     The volume dial  361  and the rotational shaft  360   a  of switch body  360   b  are coupled so as to be movable in the radial direction of the rotational shaft  360   a , as described above. Thus, an alignment error between the volume dial  361  and rotational shaft  360   a  can be canceled by a coupling portion between the volume dial  361  and rotational shaft  360   a . When the volume dial  361  is held by using the top cover  365 , even if the dial lead-out hole  378  and switch body  360   b  are displaced relative to each other, no damaging force acts on the attachment portion of the switch body  360   b  on the fourth circuit board  83 . Thus, destruction of the switch body  360   b  can be prevented. 
     As is shown in FIGS. 17 and 44, the panel  366  of top cover  365  has an icon attachment portion  384 . The icon attachment portion  384  is formed of a rectangular recess extending in the width direction of the top cover  365 . A second icon  385  is disposed in the icon attachment portion  384 . The second icon  385  has a light-transmissive icon board  386  of a synthetic resin. The icon board  386  is adhered to the icon attachment portion  384 . Three display marks  387  are linearly arranged on the icon board  386 . The display marks  387  indicate the key control content by means of the keyboard  313 . 
     The icon attachment portion  384  has through-holes  388  (only one shown) at positions associated with the display marks  387 . The through-holes  388  face the component attachment portion  323  of upper housing  6 . A light guide member  390  is supported on the component attachment portion  323 . The light guide member  390  is formed of a transparent synthetic resin material and comprises three light guide portions  391  (only one shown) associated with the display marks  387 . Each of the light guide portions  391  has a columnar shape. Each light guide portion  391  has an upper end portion engaged in the through-hole  388  and a lower end portion facing the second circuit board  81  located below the component attachment portion  323 . 
     As is shown in FIGS. 8 and 17, three light emitting diodes (LEDs)  392  are mounted on the second circuit board  81 . The LEDs  392  serve as light source for the second icon  385  and face the lower end portions of the light guide portions  391 . Light radiated from the LEDs  392  is guided to the display marks  387  through the light guide portions  391 , as indicated by an arrow in FIG.  17 . Thus, the display mark  387  associated with the turned-on LED  392  is lighted to display the key control content by means of the keyboard  313 . 
     In the state in which the display unit  3  is rotated to the third position, as shown in FIG. 44, the top cover  365  is put on the component attachment portion  323  of upper housing  6  from the upper side of the housing body  2 . At this time, the first and second leg portions  327   a  and  327   b  of display unit  3  enter the first and second insertion holes  370   a  and  370   b  in the top cover  365 , thereby covering the component attachment portion  323  of upper housing  6  and first and second hinge metal fixings  328  and  329 . At the same time, the engaging wall  375  formed at the front end of the panel  366  enters the rear end region of the keyboard support section  310  and holds the rear end portion of the support panel  314  of keyboard  313 . The top cover  165  is coupled to the board support portion  32  of frame  30  and the second brackets  332  and  342  of first and second hinge metal fixings  328  and  329  by means of the screws  364 . Thus, the top cover  365  is held on the housing body  2  while covering the component attachment portion  322 . 
     A description will now be given of the procedure for replacing the CD-ROM drive  190  with the floppy disk drive (FDD)  191 , in the case where the CD-ROM drive  190  is mounted in the first section  38  of pack storage section  31  in the computer  1  having the above structure. 
     At first, as shown in FIG. 33B, the front cover  255  of housing body  2  is slid from the locked position to the unlocked position, and the first to third engaging projections  265   a  to  265   c  are disengaged from the bottom wall  5   a  of lower housing  5  and the engaging holes  266   a  and  266   b  in the frame  30 . 
     Subsequently, as shown in FIGS. 3 and 10, the front cover  255  is rotated downward from the first position to the second position. Thereby, the insertion holes  40  and  41  of the pack storage section  31  are opened to the front side of the housing body  2 , and the ejector  300  is exposed to the opening portion of insertion hole  40  of first section  38 , as shown in FIG.  40 . If the front cover  255  is rotated from the first position to the second position, the pressing projection  293  of front cover  255  is disengaged from the pressing surface  292  of the stopper  290 , as shown in FIG.  38 A. Thus, the raising of the stopper  290  is released and the stopper  290  is forcibly lowered to the unlocked position by the urging force of the return spring  291 . The stopper  290  is pulled out of the first section  38  and disengaged from the engaging portion  216   a  of CD-ROM drive  190 . Accordingly, the stopper  290  releases the CD-ROM drive  190 . 
     The operation lever  302  of ejector  300  exposed to the insertion hole  40  is then pulled out, as shown in FIG.  40 . In accordance with the movement of the operation lever  302 , the slider  301  is drawn out and the pushing portions  304   a  and  304   b  of slider  301  push the engaging portions  216   a  and  216   b  of CD-ROM drive  190  toward the insertion hole  40 . Consequently, the CD-ROM drive  190  is pushed out of the insertion hole  40  and the interface connector  194  is disconnected from the first relay connector  160 . At last, the front end portion of the CD-ROM drive  190 , which is projected from the insertion hole  40 , is held by the fingertip and the CD-ROM drive  190  is pulled out of the first section  38 . 
     After the CD-ROM drive  190  has been drawn out of the first section  38 , the FDD  191  is inserted into the insertion hole  40  of first section  38  and the interface connector  223  of FDD  191  is connected to the first relay connector  160 . 
     Then, the front cover  255  is rotated upward from the second position to the first position. The pressing projection  293  of front cover  255  contacts the pressing surface  292  of stopper  290  from below, as shown in FIG.  38 B. The pressing projection  293  then pushes up the stopper  290  from the unlocked position to the locked position against the urging force of the return spring  291 . As a result, the stopper  290  advances into the first section  38  and engages the engaging portion  243   a  of FDD  191 . 
     When the pressing projection  293  of front cover  255  has contacted the stopper  290 , the beveled surface  298  of the pressing projection  293  is simultaneously put in slidable contact with the inclined surface  297  of slider  295 . Thereby, the slider  295  is forcibly slid from the first position to the second position against the urging force of the return spring  296 . When the front cover  255  has reached the first position, the beveled surface  298  of pressing projection  293  has passed over the inclined surface  297  of slider  295  and comes into contact with the front end face of slider  295 . Since the slider  295  is constantly urged to the first position by the return spring  296 , the urging force of return spring  296  is transmitted to the front cover  255  via the pressing projection  293  and the front cover  255  is forcibly slid from the unlocked position to the locked position. By this sliding movement, the first engaging projection  265   a  is engaged with the front edge portion of the bottom wall  5   a  and the second and third engaging projections  265   b  and  265   c  are engaged in the engaging holes  266   a  and  266   b  in the frame  30 . Thus, the front cover  255  is held in the first position. As a result, the front wall portion  257  of front cover  255  covers the hard disk drive (HDD)  250  contained in the second section  39 . In addition, the opening portion  263  of front cover  255  faces the front side of the FDD  191 . The floppy disk insertion hole  219  is exposed to the front side of the housing body  2  through the opening portion  263 . 
     According to the computer  1  with the above structure, the CD-ROM drive  190  or FDD  191  is locked in and unlocked from the first section  38  in interlock with the rotational operation of the front cover  255 . There is no need to perform a special operation for locking and unlocking the CD-ROM drive  190  or FDD  91 . Thus, the CD-ROM drive  190  or FDD  191  can be easily replaced. 
     In order to rotate the front cover  255  from the first position to the second position, it is necessary to slide, in advance, the front cover  255  from the locked position to the unlocked position. Thus, the front cover  255  is opened by the two-stage operation, and the front cover  255  is prevented from being opened carelessly. Although the CD-ROM drive  190  or FDD  191  is locked and unlocked by using the front cover  255 , the CD-ROM drive  190  or FDD  191  is prevented from being removed from the first section  38 . 
     When the front cover  255  is rotated from the second position to the first position, the front cover  255  is automatically slid to the locked position by the slider  295 . Accordingly, when the front cover  255  is closed, it should suffice to rotate the front cover  255 . The operation of closing the front cover  255  is thus simplified. 
     According to the above structure, the ejector  300  for pushing out the CD-ROM drive  190  or FDD  191  from the first section  38  is not exposed to the insertion hole  40  of the first section  38  until the front cover  255  has been rotated to the second position. As long as the front cover  255  is closed, the ejector  300  cannot be operated. An intentional operation to rotate the front cover  255  to the second position is required to pull out the CD-ROM drive  190  or FDD  191  from the first section  38 , and an erroneous operation of the ejector  300  can be prevented. 
     As has been described above, when the front cover  255  is rotated to the second position and the ejector  300  is exposed to the insertion hole  40 , the stopper  290  has already released the locking of the CD-ROM drive  190  or FDD  191 . Thus, the CD-ROM drive  190  or FDD  191  can easily be pushed out of the first section  38  by operating the ejector  300 . In addition, when the ejector  300  is operated, the stopper  290  has already been disengaged from the engaging portion  216   a  of CD-ROM drive  190  or the engaging portion  243   a  of FDD  191 . Accordingly, the stopper  290  does not interfere with the engaging portion  216   a  or  243   a . No damaging force acts on the stopper  290 , and destruction of the stopper  290  is prevented. 
     In the computer  1  having the above structure, the component attachment portion  323  extending in the width direction of upper housing  6  is formed at the rear portion of the upper housing  6 . The first and second speakers  353   a  and  353   b  and the volume dial  361  of volume switch  360 , which are replaced with relatively high frequency, are supported on the component attachment portion  323 . The component attachment portion  323  is covered by the removable top cover  365 . 
     If a need arises to replace at least one of the first and second speakers  353   a  and  353   b , the screws  364  are loosened to unfix the top cover  365 . The display unit  3  is then rotated to the third position, and the housing  325  of display unit  3  is turned to the rear side. In this state, the top cover  365  is pulled up and removed from the component attachment portion  323 . Thereby, the component attachment portion  323  is widely opened to the upper side of the housing body  2 , and the first and second speakers  353   a  and  353   b  as well as volume dial  361  are exposed to the outside of the housing body  2 . 
     As has been described above, when at least one of the first and second speakers  353   a  and  353   b  is replaced, it suffices to remove the top cover  365 . There is no need to separate the upper housing  6  from the lower housing  5 . Thus, a time-consuming work such as disassembling the housing body  2  is not required. The work for replacing the speakers  353   a  and  353   b  is simplified. 
     If the top cover  365  is removed from the component attachment portion  323 , the flange portion  361   c  of volume dial  361  is opened upward. The volume dial  361  can thus be pulled off upward from the shaft portion  360   a  of volume switch  360 . Thus, the work for maintaining the switch body  360   b  can be easily performed. 
     The top cover  365  has the engaging wall  375  which cooperates with the bottom wall  311   a  of keyboard support section  310  in clamping the support panel  314  of keyboard  313 , the keyboard  313  can be held by using the top cover  365 . Accordingly, there is no need to provide a special member for holding the keyboard  313 , and the number of parts of the computer  1  can be reduced. Moreover, if the top cover  365  is removed, the keyboard  313  is released. Thus, the keyboard  313  can be removed from the keyboard support section  310 . Therefore, it is possible to easily perform not only the work for replacing the first and second speakers  353   a  and  353   b , but also the work for replacing or maintaining the keyboard  313 . 
     The component attachment portion  323  of upper housing  6  has first and second cover portions  346   a  and  346   b  for covering the leg portions  327   a  and  327   b  of display unit  3  from below. In the state in which the component attachment portion  323  is covered by the top cover  365 , the first and second hinge metal fixings  328  and  329  can be covered by the first and second cover portions  346   a  and  346   b  and the hinge cover portions  367   a  and  367   b  of top cover  365 . Thus, there is no need to provide an exclusive-use cover for covering the first and second hinge metal fixings  328  and  329  or a structure for supporting such an exclusive-use cover. Therefore, the structure of the housing body  2  can be simplified. Furthermore, since the first and second cover portions  346   a  and  346   b  are formed integral with the component attachment portion  323 , the first and second cover portions  346   a  and  346   b  can be exactly positioned in relation to the first and second leg portions  327   a  and  327   b  and the top cover  365 , and the external appearance of the housing body  2  is improved. 
     Besides, according to the above structure, the display unit  3  is supported on the upper housing  6  by means of the first and second hinge metal fixings  328  and  329 . Thus, the display unit  3  along with the upper housing  6  can be removed from the lower housing  5 . The housing body  2  can be disassembled, simultaneously with the removal of the display unit  3 . The works for replacing and maintaining the display unit  3  are facilitated. 
     In the above embodiment, the component attachment portion is situated behind the keyboard. However, in the present invention, the component attachment portion may be situated in front of the keyboard, and the top cover covering the component attachment portion may be used as armrest. 
     Additional advantages and modifications will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details, and representative devices shown and described herein. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.