Personal computer with configurational flexibility and service features

A personal computer includes a frame unit and a top cover mounted to pivot upward and outward to the rear of the system, or alternately, upward to the side. One or more DASD storage devices may be mounted to extend downward from the top cover. A planar board is attached atop the lower side of the frame unit, where flexible mounting hardware allows the attachment of one of several types of planar boards. A central support structure includes a riser card plugged into a connector of the planar board, and a number of card connectors into which option cards can be plugged for electrical connection with the planar board. The central support structure also includes a bracket extending along the rear of the computer, having slots through which port connectors of the option cards can extend. The central support structure is held in engagement with the connector of the planar board by the top cover when this cover is closed. When the top cover is open, the DASD storage devices may be easily replaced, the central support structure may be unplugged from the planar board, and the planar board can be easily replaced or serviced. A front surface of the computer includes a door, which is opened by rotation outward and downward, to be slid inward, providing access for the replacement of media in the storage devices. This door and the top cover are separately lockable using a multi-function lock.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to the mechanical structure of a personal computer, 
and more particularly, to providing several levels of access to media and 
components within a personal computer. 
2. Background Information 
Personal computer systems typically include electronic circuits mounted on 
a planar board, with various other circuits mounted on option, or feature, 
cards plugged into the planar board by means of connectors. This method 
allows the variation of features of the computer system by varying the 
option cards installed within the system. In some personal computer 
systems, the processor chip is also mounted on a card plugged into the 
planar board. In a desk-top type of system, the planar board is fastened 
in place to the system frame near the bottom of the system. The option 
cards extend upward from the planar board, being plugged directly into the 
planar board, or being plugged into an upward-extending riser card that is 
in turn plugged into the planar board. Various electromechanical devices 
within the system, such as diskette drives and hardfiles are typically 
also installed above the planar board. 
A typical personal computer system also includes a number of other 
subassemblies installed above the planar board. Such devices may include 
the direct access storage devices (DASD devices) used to provide data and 
program storage in most personal computers. These devices include both 
devices with removable media, called floppy drives, and devices with fixed 
media, called hardfiles. A typical personal computer includes one or two 
such devices with removable media, each of which has a slot to which 
access must be available for the removal and replacement of magnetic 
media. 
As a result of such configurations, desk-top personal computer systems must 
be almost completely disassembled before the planar board can be removed 
and replaced. This requirement causes particular difficulties because the 
planar board typically has the highest failure rate among system 
components. Particular problems are associated with the removal of option 
cards connected to peripheral devices, since the cables to such devices 
must be disconnected before the cards can be removed. Thus, much time is 
wasted in disassembly and reassembly of components in the event of a 
planar problem, which may occur during the process of building and testing 
the computer in a factory, or during the subsequent operation of the 
computer in the user's office. Furthermore, in the user's office the 
additional desk space, required for the placement of various components 
removed for access to the planar board, is often not available. What is 
needed is a means to provide for easy access to the planar board and to 
DASD components for service. 
Personal computer systems are typically configured to accept a single type 
of planar board, with mounting holes in the planar board attached to a 
frame by means of screws, plastic snap fasteners, or a combination of 
screws and plastic snap fasteners. To reduce the emission of radio 
frequency interference by the system, the planar board is typically 
grounded through a number of paths. Conductive pads on the planar may be 
provided in annular spaces around mounting holes, being held against the 
frame by screws tightened through the holes. Conductive pads also may be 
provided in other locations, to be contacted by flexible spring members 
supported by the frame. Thus, the fixed locations of mounting features in 
the frame limit the system to accepting a single type of planar board. 
Since the characteristics of a computer system depend largely on the 
planar board, this limitation often means that a different frame is 
required for each different system. 
Another problem with fixed locations for mounting the planar board arises 
from relatively small variations in the locations of mounting holes in the 
planar board and in the location of mounting features used for its 
attachment to the frame. Such variations, which are to be expected with 
any practical processes for manufacturing planar boards and system frames, 
sometimes make it difficult to install a planar board in a specific frame. 
Occasionally, such variations make it impossible to perform this 
installation, so that a planar board or a frame must be scrapped in the 
manufacturing process. 
Thus, what is needed is a configurationally flexible means for mounting the 
planar board, including means for moving attachment points into various 
configurations, so that different kinds of planar boards may be 
accommodated. It is also desirable that the means for mounting be movable 
through small distances to accommodate variations in locations of features 
mounting a single kind of planar board. 
A number of personal computers, such as the IBM Personal Computer, Model 
AT, are equipped with key-operated locks that can be locked to prevent the 
removal of the top cover, and therefor to prevent access to subassemblies 
within the computer system. Such locks may also function as electrical 
switches to prevent the unauthorized use of the computers. However, such 
locks tend to leave the system in either a totally locked or totally 
unlocked condition. For example, there is no condition in which the 
computer can be operated without hindrance while its internal 
subassemblies are protected from theft. What is needed is a flexible 
locking system, offering several levels of security through the use of a 
single lock, which may be placed in any of several positions through the 
use of a single key. 
SUMMARY OF THE INVENTION 
In accordance with one aspect of the invention, there is provided personal 
computer hardware including a frame section, a planar board assembly, a 
central support structure, a top cover, a direct access storage device, 
and a cover attachment mechanism. The frame section has a generally flat 
lower side, a front frame bezel, a rear frame opening, and an open side 
opposite the lower side. The planar board assembly is fastened within the 
frame section, by a planar board attachment mechanism, to the lower side. 
The planar board assembly includes a riser connector pointing toward the 
open side. The central support structure, which is for electrically 
connecting option card assemblies with the planar board, includes a riser 
card engaging the riser connector, a number of card connectors on the 
riser card electrically connected through the riser card to the riser 
connector, and a rear attachment framework extending within the rear frame 
opening. This rear attachment framework includes a number of rear slots 
extending through the framework, with provisions for attaching a number of 
card assemblies in alignment with the rear slots and in engagement with 
various of the card connectors. The top cover has a generally flat upper 
side and an open side opposite the upper side. The direct access storage 
device is attached to the upper side, extending below the upper side, by a 
storage device attachment mechanism. The cover attachment mechanism 
attaches the top cover to the frame section along a cover attachment edge 
of the top cover and along a frame attachment edge of the frame section, 
permitting pivoting movement of the top cover between a closed cover 
position and an open cover position. With the cover in the closed cover 
position, the central support structure is held in engagement with the 
riser connector. With the cover in the open cover position, the central 
support structure can be disengaged from the riser connector. 
In accordance with another aspect of the invention, hardware is provided 
for controlling physical access within a computer system. This hardware 
includes a cover assembly, a media access door, a lock, a first locking 
mechanism, a cover locking mechanism, and a media door locking mechanism. 
The cover assembly includes a frame and a top cover, which is movable 
between a closed cover position and an open cover position. The lock has a 
rotor that can be rotated among first, second, and third lock positions, 
when a properly encoded key is inserted in a slot of the rotor. The lock 
rotor cannot be rotated between adjacent lock positions when the key is 
not inserted in the slot. The first locking mechanism is moved by rotation 
of the lock. The cover locking mechanism is moved by the first locking 
mechanism between a cover locking position, in which the cover is held in 
the closed cover position, and a cover releasing position, in which the 
cover is released from the closed cover position. The cover locking 
mechanism is in the cover locking position when the lock is in the first 
and second lock positions and in the cover releasing position when the 
lock is in the third lock position. The media door locking mechanism is 
moved by the first locking mechanism between a media door locking 
position, in which the media access door is held in the closed media door 
position, and a media door releasing position, in which the media access 
door is released from the closed media door position. The media door 
locking mechanism is in the media door locking position when the lock is 
in the first lock position, and in the media door releasing position when 
the lock is in the second and third lock positions.

DETAILED DESCRIPTION 
FIGS. 1 through 15 show various aspects of a personal computer built in 
accordance with the present invention, with FIGS. 1 and 2 showing the 
computer in a closed position, as it is normally operated. FIGS. 3, 5, and 
6 show different ways the computer may be configured, with the computer in 
an open position, in which it may be serviced or reconfigured. FIG. 4 and 
FIGS. 7 through 15 show various assemblies forming parts of the computer. 
FIGS. 29 and 30 show optional assemblies that may be added to the 
computer. 
Alternative applications of the present invention are shown in FIGS. 31 
through 35, with alternate methods for providing certain of the features 
of the computer being shown in FIGS. 31 through 33. FIG. 34 shows how an 
alternate computer may be built to provide a different system bus. FIGS. 
35-37 show a larger computer built using the lower portion of the computer 
of FIGS. 1 through 13, together with a number of concepts of the present 
invention. FIGS. 38 and 39 show a personal computer built in accordance 
with the present invention to have a top cover which pivots open along a 
right side edge, instead of along a rear edge. 
At various points in the specification and in the appended claims, 
references are made to directions, such as "upward" or "rearward." These 
references, which are made to simplify discussion concerning the relative 
locations of certain features, assume that the computer is sitting on a 
desk, with the frame facing down, the top cover facing up, and operational 
controls facing forward. These references are not intended to limit the 
scope of the present invention; a computer built in accordance with the 
present invention can be used in various orientations, as demonstrated 
particularly through the wall-mounting hardware described in reference to 
FIGS. 14 and 15. 
Referring first to FIG. 1, which is an isometric view of the computer as 
viewed from in front, above, and to the right, personal computer 10 
includes a top cover 12 and a frame 14, which together generally enclose 
various internal electronic circuits. Top cover 12 includes an upper front 
bezel 16, while frame 14 includes a lower front bezel 18. A number of 
controls 24 are provided for various purposes, such as turning computer 10 
on and off. Since the enclosure of computer 10 may surround storage 
devices with removable media, such as diskette drives, a pivotable media 
access door 26 is provided to allow access for the insertion and removal 
of such media. 
Referring to FIGS. 2 and 3, at the rear of computer 10, a pivoting bail 27 
is pivotally mounted to top cover 12 and to frame 14. This arrangement 
allows both upward and rearward pivotal separation of top cover 12 and 
frame 14, as top cover 12 is moved from the closed position of FIG. 1 into 
the open position shown in FIG. 3, for repair, adjustment, or 
reconfiguration of internal components. Before this cover opening motion 
can occur, top cover 12 is released from frame 14 by rotating a lock 
mechanism 28, moving a cover latch 29 out of engagement with a latching 
slot 30. In this way, top cover 12 is released to rotate upward while 
remaining in connection with frame 14 by means of pivoting bail 27. 
Along each side of the interface between top cover 12 and frame 14, 
electrical continuity is provided by means of a number of flexible contact 
spring segments 31, which provide multiple contact points spaced apart 
from one another through distances compatible with the reduction of the 
emission of electromagnetic energy from the computer 10. This type of 
contact between major shielding covers has been found to be particularly 
beneficial in reducing the emission of such energy, which may otherwise 
interfere with the transmission of communication signals. 
Personal computer 10 may be assembled into a large number of 
configurations. As shown in FIG. 3, major components attached within frame 
14 include, for example, a power supply 32, a cooling fan 34, and a planar 
board 36. A transverse duct 38 directs cooling air from outlet 40 of fan 
34 to a space above planar board 36. A baffle 42, extending above the left 
portion of planar board 36 directs air from transverse duct 38, above this 
portion of the planar board, to outlet slots 44 in the left side of frame 
14. When top cover 12 is closed, outer slots 46 are generally aligned with 
outlet slots 44, so that air can flow outward from the space below baffle 
42. Those circuit devices most requiring cooling air may be mounted on 
this side of planar board 36, extending upward into this airflow. Fan 34 
is a centrifugal-flow device sucking air through an inlet hole pattern 48 
in its top surface and through a similar hole pattern (not shown) in its 
lower surface. Fan 34 is mounted on a support bracket 50 above the 
adjacent surface 52 of frame 14, exposing the hole pattern of the lower 
surface. Air is drawn into fan 34 through power supply 32, which has a 
number of external holes 53 in its rear surface 54 (shown in FIG. 2), 
allowing the inward flow of air from outside, and through a number of 
holes 55 allowing the flow of air between power supply 32 and fan 34. An 
additional inlet hole pattern 56 is provided in top cover 12 to allow the 
flow of additional air from outside computer 10 into fan 34. 
Planar board 36 includes a number of generally necessary circuits, along 
with means for electrically connecting a number of optional circuits. SIMM 
modules 58 (single in-line memory modules) may be plugged into appropriate 
sockets (not shown) on planar board 36 to provide a random access memory 
function. 
Referring to FIGS. 2 and 3, rear surface 54 of power supply 32 also 
includes an appliance coupler 57, into which a line cord may be plugged 
for connection to a standard alternating-current power source. Connectors 
60 extend along a rear edge of planar board 36, through apertures in a 
planar shielding bracket 61, for connection to various external cables 
(not shown). Various of these connectors 60 are configured for connection 
to input devices, such as a keyboard (not shown) or mouse (not shown), 
while others of these connectors 60 may be configured for connection to 
peripheral devices (not shown), such as a display unit and a printer, or 
to communication cables (not shown). 
Referring to the cross-sectional elevation of FIG. 4, additional, optional 
circuits may be provided by means of option cards 62, which are plugged 
into connectors 63 of a riser card 64. Riser card 64 is in turn plugged 
into a connector 65 of planar board 36. Thus, electrical connections are 
made from planar board 36 through connectors 65 and 63, and through 
circuit traces on riser card 64, to option cards 62. The I/O channel of 
the system, for example, may be connected to option cards 62 in this way. 
As shown in FIG. 4a, the use of surface mount technology, in which formed 
terminal elements 66 extending from connectors 63 are soldered to 
conductive pads 67 at the surface of riser card 64, allows the placement 
of connectors 63 at identical locations on each side of riser card 64. 
Terminal elements 66 are integral portions of spring terminals 67a which 
extend within each connector 63 to contact conductive pads on an inserted 
option card 62 (shown in FIG. 4). Conductive pads 67 are electrically 
connected to pads 67b on the surface of riser card 64, by means of 
conductive traces 67c. When riser card 64 is inserted into connector 65 of 
planar board 36 (shown in FIG. 4), electrical connections within the 
connector 65 connect pads 67b to various circuits within the planar board. 
Referring again to FIGS. 2 and 3, a slotted bracket 71 extends partially 
across the rear of computer 10, behind the region in which option cards 62 
may be placed. Each option card 62 is part of an assembly including a card 
bracket 72, which is attached to slotted bracket 71 by means of a screw 
73, closing a slot 74 in bracket 71. Some option cards also include port 
connectors 76 (shown in FIG. 2), which are directed outward through 
apertures in card brackets 72 and through slots 74, to be used for the 
attachment of cables to peripheral devices or for the attachment of 
communication cables (not shown). 
Referring to FIGS. 3 and 4, limited option cards 68, which are installed in 
the lowest connectors 66 on riser card 64, are not directed at a 
corresponding slot 74 in bracket 71, and are not attached to a card 
bracket 72. Preferably, limited option cards 68 are used for functions, 
such as extended system memory, which do not require cable attachment to a 
peripheral device. Blank brackets 77, which are not attached to option 
cards 62, are used to fill those slots 74 in slotted bracket 71 which do 
not correspond to an installed option card 62. Like each card bracket 72, 
each blank bracket 77 is removably attached to slotted bracket 71 by means 
of a screw 73. 
Referring to FIGS. 3 and 4, a "T"-shaped central support structure 79 
includes slotted bracket 71 and an a riser support bracket 80, which 
extends forward to divide the space above planar board 36, being attached 
to riser card 64 by means of screws 82. These brackets 71 and 80 are 
attached to one another, for example, by welding. Slotted bracket 71 
generally fills a gap in the rear of computer 10, between power supply 32 
and the left side of the computer. With computer 10 in the open position 
of FIG. 3, central support structure 79 may be installed by simply 
plugging riser card 64 into planar board connector 65. Similarly, 
structure 79 may be removed by simply unplugging riser card 64 from 
connector 65. With computer 10 in the closed position of FIG. 1, central 
support structure 79 is held in place, with riser card 64 plugged into 
connector 65, by means of the proximity between top cover inner surface 84 
and the top surfaces of brackets 71 and 80. The stability of central 
support structure 79 is further enhanced by contact between a 
downward-extending front leg 83, formed as an integral portion of riser 
support bracket 80, and an adjacent inner surface (not shown) of frame 14. 
Top cover 12 includes slotted channels 86, which may be used to mount a 
number of DASD devices 88 in such a way that these devices are moved 
upward and rearward, providing access to option cards 62, to planar board 
36, and to the devices 88 themselves by moving top cover 12 into the open 
position shown in FIG. 3. The acronym "DASD," for direct access storage 
device, is used to reflect the type of magnetic storage device used in 
most personal computers. A DASD device, such as a magnetic disk device 
(floppy or hardfile), provides direct access to data instead of requiring 
that data be read from the beginning of a data record, such as data stored 
sequentially on a magnetic tape. DASD devices 88 may be attached to 
circuits mounted to frame 14 by means of flexible cables, such as cable 
90, which are plugged into connectors atop planar board 36. Certain DASD 
devices may alternately be connected to various circuit cards 62, by means 
of flexible cables 92. In either case, the cables are routed near the rear 
of computer 10, where pivoting motion occurs with pivot bail 27, so that 
the cables are unfolded as computer 10 is opened and refolded as computer 
10 is closed. 
The configuration shown in FIG. 3 includes one DASD device 88, directly 
behind media access door 26, and another DASD device 93 in a location away 
from door 26. Thus, DASD device 88 preferably uses removable media, such 
as diskettes, while DASD device 93 preferably includes fixed media, being, 
for example, a hardfile. 
The spaces above planar board 36 may be used for option cards 62 extending 
from central support structure 79, and/or for DASD devices 88 extending 
downward from top cover 12. In the example of FIG. 3, two full-length 
option cards 62 are be installed above the right side of planar board 36. 
SIMM memory modules 58 and baffle 42 lie below DASD devices 88 with top 
cover 12 closed, so these elements can be present even with upwardly 
adjacent DASD devices 88. Thus, a flexible use of space within computer 10 
is provided by the means for attachment of DASD devices 88 and option 
cards 62. 
In order to service a personal computer, it is necessary to obtain access 
to various subassemblies for repair or replacement. This type of access is 
also necessary for making configurational changes, such as adding circuits 
to perform additional functions. Access to the internal hardware of 
personal computer 10 is easily obtained by opening top cover 12 after lock 
28 is rotated to disengage latch 29 from slot 30. A central electronic 
assembly 93a, consisting of central support structure 73 and of option 
cards, such as cards 62, and other devices attached to this structure 73, 
is then removed by lifting straight upward, so that riser card 64 is 
unplugged from planar board connector 65. To provide access to planar 
board 36, central electronic assembly 93a may then be hung, by means of a 
hole 93b in riser support bracket 80, on a hook 93c provided in top cover 
12 for this purpose. At this point, planar board 36, being completely 
exposed from above, can be easily removed for service or replacement. 
As shown in FIG. 2, many option cards 62 include external connectors 76 
extending outward through slots 74 in slotted bracket 71. In accordance 
with the typical usage of a personal computer, these connectors 76 are 
variously connected by means of cables (not shown) to peripheral devices 
(also not shown). Referring again to FIG. 3, when central electronic 
assembly 93a is hung on hook 93c, the cables extending from external 
connectors 76 can extend through the opening at the rear of computer 10 
between cover 12 and frame 14. Thus, it is unnecessary to unplug the 
cables attached to external connectors 76 to obtain access to planar board 
36 or to other internal components. 
In this way, the application of the present invention offers a significant 
number of serviceability advantages compared to computers of the 
background art. In a typical computer of the background art, various DASD 
devices fastened in place above the planar board must be removed before 
access to the planar board can be obtained. On the other hand, in personal 
computer 10, DASD devices 88 and 93 are moved out of the way as top cover 
12 is opened. In a typical personal computer of the background art, 
various option cards are individually attached within a framework, either 
to the planar board by means of a number of connectors on the planar 
board, or to a riser card in turn connected to the planar board. In either 
of these cases, any external cables to peripheral devices must be 
disconnected, and each option card must be disconnected, both from its 
electrical connection through a connector and from its mechanical 
connection with the framework, to be removed completely from the computer 
system, before access can be obtained to the planar board. On the other 
hand, in personal computer 10, the option cards 62 form part of central 
electronic assembly 93a, which can be removed intact by disconnection from 
the single planar board connector 65 for access to the planar board. In 
personal computer 10, this operation does not require the disconnection of 
individual option cards 62, or the disconnection of cables to external 
peripheral devices. Ease of access to planar board 36 is particularly 
important, since the planar board of a personal computer is typically the 
component having the highest failure rate, and hence the most frequent 
need for service. 
Many of these advantages of the present invention are also evident during 
the manufacturing process, where planar boards also tend to experience 
relatively high failure rates. During the manufacturing process, it is 
often necessary to repair or replace a planar board to fix a problem found 
during system testing. The ease of access to the planar and to other 
internal components with the present invention provides substantial time 
and cost savings during the manufacturing process. 
The configuration of central electronic assembly 93a also affords 
significant advantages relative to minimizing the overall size of personal 
computer 10 and relative to the servicing and reconfiguration of option 
cards 62. In computer systems of the background art, the framework for 
mounting individual option cards is provided by the framework of the 
computer system. Thus, in computer systems of the background art, physical 
access to both mechanical and electrical attachments must be obtained with 
the card installed within the system. On the other hand, in personal 
computer 10, the framework for mounting individual option cards 62 is 
provided by central support structure 79, which is removed as a part of 
central electronics assembly 93a. Physical access to mechanical and 
electrical attachments is afforded with this assembly 93a removed from its 
connection with planar board 36. In this example, mechanical connection is 
provided by fastening card bracket 72 to slotted bracket 71 with a screw 
73. Thus, since access to screw 73 with a screwdriver is provided with 
central electronics assembly 93a removed, it is not necessary to allow 
clearance for the operation of screwdriver on each side of slotted bracket 
71. Specifically, screwdriver clearance space is not required between 
slotted bracket 71 and power supply 32. Furthermore, since individual 
option cards 62 are removed and installed with central electronics 
assembly 93a removed, it is never necessary to remove one option card 62 
to achieve access to the space for another card 62. 
Referring to FIG. 5, an alternative allocation of space above planar board 
36 is provided through the use of a short option card 94 in an uppermost 
position provided by "T"-shaped central support structure 79, in place of 
a full-length option cards 62. When a short option card 94 is installed in 
this way, space is provided in front of the option card for the 
installation of a second DASD device 88 in a front space adjacent to media 
access door 26. In the closed position, the second DASD device 88 is 
brought into a space above the front right portion of planar board 36, in 
front of the short option cards 94. This configuration thus offers two 
DASD devices 88 directly behind media access door 26; each of these 
devices 88 can employ removable media. A single DASD device 93, which may 
be, for example, a hard file, is located away from door 26. The popular 
system configuration including a 31/2-inch diskette drive, a 51/4-inch 
diskette drive, and a hardfile can be built in this way. Thus, the present 
invention easily provides for the alternative use of the same space for 
option cards or for DASD devices. 
FIG. 5 also shows a bracket assembly 95 holding a speaker 95a and various 
switches and indicators 95b in locations adjacent to corresponding 
features of top cover 12 in its closed position. Thus, a pattern of holes 
96 in top cover 12 is brought into place adjacent to speaker 95a, while 
pushbuttons and apertures 96a are adjacent to switches and indicators 95b. 
This bracket assembly 95 is equally applicable to the configuration shown 
in FIG. 3; it has been omitted from FIG. 3 only to reveal the features 
which would otherwise be hidden. 
Referring to FIG. 6, an "H"-shaped central support structure 97 may be used 
in place of the "T"-shaped central support structure 79 previously 
discussed in reference to FIGS. 3 and 4. Support structure 97 is 
particularly designed to take advantage of the space savings made 
available through the use of short option cards 94 (shown in FIG. 5). 
Thus, support structure 97 includes five connectors 63 on each side, each 
of which is connected to the system bus through a riser card (not shown). 
In FIG. 6, these connectors 63 are individually indicated as connectors 
63-1 through 63-5. Support structure 97 includes a front slotted bracket 
98 having a slot 98a on each side, aligned with an adjacent connector 63-1 
in such a way that the bracket of a short option card 94 installed in this 
connector 63-1 extends across the corresponding slot 98a. The 
configuration of front slotted bracket 98 corresponds to that of rear 
slotted bracket 71 in such a way that each card bracket 72 and each blank 
bracket 77 can be fastened to front slotted bracket 98 in the manner used 
for attachment to rear slotted bracket 71. Slotted bracket 98 extends atop 
transverse duct 38, being fastened, for example by welding, to a central 
support member 99 at a tab 99a. Thus, the concept of a central electronics 
assembly is implemented either with a central support structure 79 having 
a single end at which card brackets 72 may be attached, or with a central 
support structure 97 having two opposite ends at which card brackets 72 
may be attached. 
In many applications, it is necessary to obtain access to slots 98a from 
outside system 10. For example, a short option card 94 (shown in FIG. 5) 
may be connected to an external peripheral device by means of a cable from 
a connector extending through a card bracket 72 of the short option card 
94. To obtain such access, an alternate lower bezel 100, which includes a 
pair of rotatable lower access doors 100a and 100b, is used in place of 
lower bezel 100. 
Central support structure 97 provides on each side a lower position in 
which a single long card without a bracket 72 may be placed in a connector 
63-2, or in which two short cards without brackets 72 may be placed, using 
connectors 63-2 and 63-3. In a central position, a single long card 62 
with a bracket 72 may be placed in a connector 63-4, or two short cards 94 
with brackets 72 may be placed, using connectors 63-4 and 63-1. In an 
upper position, using connector 63-5, a single short card 94 with a 
bracket 72 may be placed, or a single long card 62 with a bracket 72 may 
be placed. However, if a long card 62 is placed in the upper position, no 
DASD device may be placed above it. If a short card 94 is placed in the 
upper position, a single DASD device 88 may be installed on the 
corresponding side toward the front (as shown in FIG. 5). 
As further shown in FIG. 6, a total of four DASD devices--two DASD devices 
88, which are located near door 26 for media access, and two DASD devices 
93, which are preferably devices with fixed media--may be installed to 
extend downward from top cover 12 if no option card 62 or 94 is installed 
in connector 63-1. A configuration of the general type shown in FIG. 6 may 
be used as an expansion box to provide additional data storage capability 
to a personal computer system. In such an application, the expansion box 
functions as a peripheral unit attached to a base system. A planar board 
having the circuit functions typically associated with such an circuit 
board may not be required. A different sort of planar board, having 
various connectivity features with limited logical functions may be 
provided instead. 
General configurational features of the present invention have been 
discussed above with reference to FIGS. 1 through 6. More specific 
hardware features, variously applied in the implementation of these 
general features, will now be discussed with references being made to 
FIGS. 7 through 28. 
The pivoting arrangement joining top cover 12 with frame 14 will first be 
discussed in greater detail, with reference being made to FIGS. 2, 7 and 
8. FIG. 2 is a rear elevational view of computer 10. FIGS. 7 and 8 are 
cross-sectional elevational views taken as indicated by lines VII--VII in 
FIG. 2, with FIG. 7 showing the computer in a closed position, while FIG. 
8 shows the computer in an open position. 
Referring to FIG. 2, pivot bail 27 is a formed and welded rod structure 
extending generally around an inner periphery formed by the rear edges of 
frame 14 and top cover 12. A lower rod portion of 101 of bail 27 is 
pivotally mounted to frame 14 by means of rolled hinge tabs 102 extending 
from frame 14. In turn, top cover 12 is pivotally mounted on an upper rod 
portion 103 of bail 27 by means of hinge couplings 104 extending from top 
cover 12. 
As shown in FIG. 7, when personal computer 10 is in its closed position, 
upper rod portion 103 is held adjacent to rear surface 54 of power supply 
32, by the engagement of cover latch 29 in slot 30 (shown in FIG. 3), 
which prevents the rearward motion of top cover 12. 
As shown in FIG. 8, when personal computer 10 is in its open position, 
upper rod portion 103 is pivoted to the rear, away from power supply rear 
surface 54, with lower rod portion 101 turning in rolled hinge tabs 102. 
Bail 27 includes, at each end, a "U"-shaped inward-extending portion 105 
adjacent to a bail support bracket 106 extending upward from frame 14. 
Each bracket 106 includes a formed tenon 108 extending into the adjacent 
inward-extending portion 105. As bail 27 is pivoted rearward, a corner 107 
of inward-extending portion 105 on each side engages tenon 108, spreading 
portion 105 slightly, so that bail 27 is held in its fully rearward 
position by frictional forces. 
Top cover 12 is also rotated upward, with hinge couplings 104 turning on 
upper rod portion 103. On each side, a travel limiting linkage 110 is 
provided to control the angle through which top cover 12 is rotated and to 
hold cover 12 in its open position. This linkage 110 includes a lower link 
112 pivotally mounted to frame 14 by means of a pivot 113 attached to 
support bracket 106, and an upper link 114 pivotally mounted to top cover 
12 by means of a pivot 115. Links 112 and 114 are also pivotally mounted 
to one another at a central pivot 116. A tab 118 from lower link 112 
restricts the motion of pivot 116 in the direction of arrow 120 after 
linkage 110 is fully opened, by closing against a stopping surface 121 of 
upper link 114, as shown in FIG. 8. Links 112 and 114 are configured so 
that, when linkage 110 is fully opened, central pivot 116 is located in 
the direction of arrow 120 from a line between pivots 113 and 115. When 
top cover 12 is fully opened, linkage 110 is straightened as shown in FIG. 
8. With linkage 110 straightened in this way, a force tending to close 
cover 12 results in the generation of a torque tending to move pivot 116 
in the direction of arrow 120. However, since such motion is impossible, 
the linkage serves to hold cover 12 fully open. Thus, top cover 12 cannot 
be closed until central pivots 116 on each side are manually moved the 
direction opposite arrow 120 to release the cover 12. 
Referring again to FIG. 3, as top cover 12 is moved upward and to the rear, 
clearing the space above planar board 36, allowing central support 
structure 79 to be unplugged and removed or replaced, and allowing access 
to planar board mounting screws at any location within the boundaries of 
planar board 36. 
The method for mounting DASD devices 88 within top cover 12 will now be 
discussed in greater detail, with particular reference being made to FIGS. 
9 and 10. FIG. 9 is a front view of personal computer 10, with media 
access door 26 shown in a lowered (open) position, stored under the front 
portion of DASD devices 88. Also, in FIG. 9 a portion of cover 12 is cut 
away to reveal the mounting of devices 88. FIG. 10 is a partial 
cross-sectional side view of top cover 12, taken in the direction 
indicated by section lines X--X in FIG. 9. 
Referring to FIGS. 9 and 10, a device mounting bracket 124, including a 
number of slotted channels 86, is attached by welding inside top cover 12. 
Each DASD device 88 is attached to bracket 124 by means of a pair of 
sideplates 126 with tabs 128 extending upward into the slots 130 of 
channels 86. These sideplates 126 are mounted to the DASD devices, for 
example, by means of screws 129. Two channels 86 form mounting surfaces 
above the leftmost position, in which a DASD device 88 is installed, while 
three channels 86 form mounting surfaces above the rightmost position, in 
which a wider DASD device 131 is installed. Thus, the leftmost position is 
configured for mounting 31/2-inch DASD devices, while the rightmost 
position is configured for mounting either 31/2-inch or 51/4-inch DASD 
devices. 
FIG. 9 also shows some of the spatial relationships among top cover 12, 
central support structure 79, and DASD devices 88. Central support 
structure 79, including the uppermost option card connectors 63-5, fits 
between installed DASD devices 88. This is why as many as four DASD 
devices may be installed if no cards are installed in uppermost connectors 
63-5, as in the configuration of FIG. 6. However, if an option card is 
installed in one of the uppermost connectors 63-5, a DASD device cannot be 
installed in an adjacent position. Thus, the configuration of FIG. 3 has a 
daughter card in uppermost connector on the right side of central support 
structure 79, but not on the left side of this structure 79, with DASD 
devices 88 and 93 installed on the left side of this structure 79. 
Central support structure 79 extends upward into close proximity with an 
adjacent underside of top cover 12. This proximity holds the riser card 64 
of structure 79 in engagement with central connector 65 of the planar 
board 36 (shown in FIG. 4), as long as top cover 12 remains in a closed 
position. When cover 12 is opened, central support structure 79 can be 
easily disengaged from central connector 65 for system servicing or for 
configurational changes, 
As shown in FIG. 10, each DASD device 88 or 93 is installed by moving the 
device upward and to the rear, in the direction of arrow 134. After 
installation, each tab 128 of sideplate 126 extends upward into a channel 
86 through a slot 130. A notch 132 of each tab 128 holds the associated 
DASD device 88 or 93 in place by engagement with an adjacent end of a slot 
130. A latching mechanism, including a flexible cantilever spring 136 
welded inside channel 86 at an attachment region 138, is provided to 
retain device 88 or 93 by preventing forward motion after installation. 
Cantilever spring 136 includes a latching tip 140, which extends partially 
across an adjacent slot 130. As the corresponding tab 128 is inserted into 
this slot 130, the latching tip 140 is deflected upward. As tab 128 is 
subsequently moved rearward in the direction of arrow 134, latching tip 
140 is cleared to return downward, into its undeflected position, blocking 
subsequent forward motion in the direction opposite arrow 134. Cantilever 
spring 136 also includes a force-loading tip 142, which applies a downward 
force on an upstanding cam portion 144 of sideplate 126, which is thereby 
held downward, with the surfaces of notches 132 resting against the 
internal surfaces 146 of channels 86. In this way, clearance distances 
between adjacent surfaces are avoided. Such clearance distances could 
otherwise cause rattling and shock loads, which could damage DASD devices, 
during the transport of computer 10. 
Cantilever spring 136 also includes a tab 148 extending outward through a 
slot 150 in channel 86. The DASD unit, such as DASD unit 88, attached to 
sideplate 126 may be removed as tab 148 is held upward, deflecting spring 
136 until latching tip 140 is deflected upward past the adjacent tab 128. 
The DASD unit may then moved forward, in the direction opposite arrow 134, 
and downward to be disengaged from channel 86. 
FIGS. 11 through 13 show a method used to attach planar board 36 within 
frame 14, with FIG. 11 providing a plan view showing the use of the method 
to attach either of two different types of planar boards, with FIG. 12 
providing cross-sectional elevation through the attachment mechanism used 
by this method, taken as indicated by section lines XII-XII in FIG. 11, 
and with FIG. 13 providing an isometric view of this attachment mechanism. 
Referring first to FIG. 11, a mounting plate 176 is attached inside frame 
14, for example by welding at various tabs 178. Mounting plate 176 
provides a number of attachment holes 180, each of which defines a 
location at which planar board 36 may be fastened. In general, mounting 
plate 176 is configured to provide for the attachment of any one of a 
number of different planar boards, with the required attachment points for 
any one planar board being a subset of the total number of attachment 
holes 180. For example, mounting plate 176 may be configured for the 
attachment of either planar board 36, having a mounting hole 182, or of an 
alternate planar board 184, having a mounting hole 186 at a position not 
corresponding to that of mounting hole 182. 
Referring also to FIG. 12, to allow the alternate attachment of planar 
boards 36 and 184, mounting plate 176 includes a hole 180 corresponding to 
the location of each mounting hole 182 and 186. The attachment of planar 
board 36 is accomplished by means of a screw 188 extending through 
mounting hole 182 to engage a threaded surface 190 of a formed nut 192. 
Planar board 36 is clamped in a spaced-apart relationship with mounting 
plate 176 through the use of a formed spacer 194. 
Referring also to FIG. 13, hole 180 and formed nut 192 include particular 
provisions for allowing the installation of formed nut 192 and spacer 194 
to mounting plate 176 after plate 176 is welded in place within frame 14. 
Nut 192 includes three angularly spaced flange segments 196, which fit 
through three outward-extending aperture segments 198 within each hole 
180. Formed nut 192 and spacer 194 are assembled together with tapered 
upstanding portion 200 of formed nut 192 extending within central portion 
202 of spacer 194. Upstanding portion 200 includes three outward-extending 
lanced tabs 204, which snap into three slots 205 within upstanding portion 
206 of formed spacer 194 as spacer 194 is brought into engagement with nut 
192. In the process of attaching a planar board, such as planer board 36 
or alternate planar board 184, assemblies thus formed of nuts 192 and 
spacers 194 are inserted into holes 180 corresponding to the locations of 
mounting holes 182 in the planar board to be attached. This insertion is 
accomplished with flange segments 196 dropping through aperture segments 
198. Each of these assemblies is then rotated in a hole 180, so that the 
inward extending tabs 208 of the hole 180 are clamped between flange 
segments 196 of formed nut 192 and flange 210 of spacer 194 when screw 188 
is tightened in the direction of arrow 210a in threaded surface 190 of nut 
192. These tabs 208 extend inward between adjacent aperture segments 198. 
To assure that this tightening process leaves flange segments 196 aligned 
to clamp the tabs 208, each tab 208 includes a downturned portion 211 
restricting motion beyond an angle at which flange segments 196 are fully 
under the tabs 208. 
Some or all of the areas around mounting holes, such as mounting holes 182 
and 186, on a typical planar board are used to provide electrical 
grounding for various ground planes or other circuits within the board. 
Conductive pads around the mounting holes on, one or both sides of the 
planar board, electrically connected to circuits needing the grounding 
function, are provided for this purpose. For example (as shown in FIG. 11) 
a conductive pad 209 may be provided around hole 182. Effective grounding 
of this kind is required to minimize the emission from the system of radio 
frequency interference (RFI). To be effective in this regard, the 
grounding means must be capable of carrying radio frequency signals. 
In the structure described above, mounting plate 176 is used with spacer 
194 and formed nut 196 to provide electrical grounding paths capable of 
carrying radio frequency electrical signals. These parts are preferably 
composed of metallic materials with surface coatings minimizing the 
formation of surface oxidation. Such materials and coatings are well known 
to those skilled in the art. This assembly is particularly effective in 
providing this kind of electrical grounding, because relatively large 
contact surface areas are available, and because relatively high contact 
forces can be derived from the thrust force provided by tightening screw 
188 in threaded surface 190. Thus, as screw 188 is tightened, the lower 
surface 211a of planar board 36 is clamped directly to the upper surface 
of spacer 194. If electrical grounding is to occur at this location, a 
conductive pad planar board 36 includes a conductive pad on its lower 
surface 211a around hole 184, so this clamping provides a suitable contact 
between this conductive pad and spacer 194. Furthermore, as screw 188 is 
tightened, tabs 208 are clamped tightly between flange segments 196 of nut 
192 and flange 210 of spacer 194, providing suitable contact between 
spacer 194 and mounting plate 176. A secondary grounding path may also be 
provided through a pad 187 on the upper surface of planar board 36 to the 
underside of the head of screw 188, through the threaded portion of screw 
188 to the threaded surface 190 of nut 192, and through flange segments 
196 to tabs 208. 
Referring to FIG. 12, planar board 36 is generally of a modern type, having 
conductive traces and electronic components on both sides. On each side of 
planar board 36, an annular space around each mounting hole 182 is 
reserved for mounting, and often for electrical grounding, purposes, being 
free from components and traces except for conductive grounding pads, such 
as pad 209 (shown in FIG. 11). However, locations corresponding to the 
places used for mounting other types of planar boards cannot be expected 
to be free from components or circuit traces. Therefore, the ability to 
move nut 192 and spacer 194 between the various holes 180 in mounting 
plate 176 is particularly important; along with a capability for providing 
mounting hardware where it is needed, this method provides a capability 
for removing mounting hardware from positions where it is not needed, and 
where it would otherwise interfere with mounting a planar board by 
contacting circuit traces and electronic components. 
These capabilities provide an advantage in the manufacturing process, 
allowing a single frame 14 to be used with a number of different types of 
planar boards, such as planar boards 36 and 184, to build different system 
models. Furthermore, these capabilities provide an advantage of allowing 
subsequent upgrading to a new type of planar having a different mounting 
configuration. 
Referring to FIG. 14, the underside 212 of frame unit 14 includes four foot 
structures 214, each of which provides an elastomeric pad 215, 
establishing an appropriate surface for contact with a furniture surface, 
such as a desk top, and a keyhole-shaped aperture 216 for accepting the 
head portion of a headed fastener, such as a screw of nail, which may be 
used to hang computer 10 on a wall surface. Preferably, when the computer 
10 is hung from a wall surface, two of the foot structures 214 adjacent to 
a side surface 217 are used in this way, so that the system unit is hung 
with the upper bezel 16 facing toward either the right or left on the 
wall. When the computer 10 is hung in this way, the servicing or 
reconfiguration of components is easily accomplished by opening top cover 
12 as previously described; there is no need to remove the computer 10 
from its position on the wall for this purpose. 
Referring to FIG. 15, each foot structure 214 includes a housing 218 
fastened to the underside of frame 14 by means of four screws 219, each of 
which extends downward through a hole 220 provided in frame 14 to engage a 
hole 221 in housing 218. Housing 218 is preferably composed of a 
thermoplastic resin material. An elastomeric pad 215 is adhesively 
attached to a lower surface 222 of housing 218. Keyhole-shaped apertures 
223 and 224 are also provided in housing 218 and elastomeric pad 215, 
respectively. (Wall sections of housing 218 are partially cut away in FIG. 
15 to reveal lower surface 222 and aperture 223.) 
Referring to FIGS. 14 and 15, computer 10 may be hung from the wall using 
two of these structures 214 to engage headed fasteners (not shown). The 
computer 10 is first placed with the heads of the headed fasteners 
extending through the enlarged portions of keyhole-shaped apertures 223 
and 224. The computer 10 is then allowed to slide downward, so that the 
head of each fastener is trapped between a pair of flanges 225, extending 
to define the narrowed portion of aperture 223, and an adjacent surface of 
underside 212 of frame 14. Computer 10 may be subsequently removed from 
the wall by lifting upward, so that the fastener heads are again aligned 
with the enlarged portions of keyhole-shaped apertures 223 and 224, and by 
pulling outward from the wall. 
The operation of media access door 26, which is opened to provide access to 
DASD devices 88 for the removal and replacement of magnetic media, will 
now be discussed, with particular reference being made to FIGS. 16 through 
19. FIG. 16 is a right cross-sectional elevation, taken as indicated by 
section lines XVI--XVI in FIG. 6. FIG. 17 is a partial rear 
cross-sectional elevation, taken as indicated by section lines XVII--XVII 
in FIG. 16, showing particularly the internal features of door 26. FIG. 18 
is another partial rear cross-sectional elevation, taken as indicated by 
sections lines XVIII--XVIII in FIG. 16, showing particularly metallic 
structures used for electromagnetic shielding. FIG. 19 is a partial 
cross-sectional plan view, taken as indicated by section lines XIX--XIX in 
FIG. 17, showing the engagement between the ends of door 26 and the 
opening for this door within upper bezel 16. As shown in FIG. 16, a 
provision is made for allowing media access door 26, in upper bezel 16, to 
be pivoted downward manually and to be pushed into a pocket 228 in an open 
horizontal orientation indicated by dashed lines at 230. 
Referring to FIGS. 16 and FIG. 17, each end of door 26 is held in a closed 
position, at its top edge by means of a slotted tab 232, near each (right 
and left) end of the door 26, engaging a downward-extending tab 234, and 
at its lower edge by means of a cylindrical tab 236 engaging a downward 
extending portion of a slot 238. Cylindrical tab 236 extends at each end 
of the door from the lower end of a descending support structure 240. A 
housing 242 of upper bezel 16 includes, outwardly adjacent to each end of 
door 26, a sidewall portion 244 extending into system 10. Each sidewall 
portion 244 includes, directed toward the adjacent door 26, the door 
guiding slot 238. Door 26 and housing 242 are preferably composed of 
suitable plastic resin materials, allowing the fabrication of slotted tabs 
232, support structures 240, and cylindrical tabs 236 as integral portions 
of door 26, and further allowing the fabrication of downward-extending 
tabs 234 and sidewall portions 244 with slots 238 as integral portions of 
housing 242. 
Referring to FIGS. 16 and 18, the metal enclosure 246 of top cover 12 
includes a downward-extending front portion 248 with a slot 250 through 
which DASD devices 88 may extend. A "U"-shaped flexible shield 252 extends 
below a lower edge section 254 of front portion 248, providing an 
electromagnetic shield around pocket 228. Front edges of shield 252 are 
divided into lip portions 256 and intervening tab portions 258, which 
provide electrical contact with enclosure 246 by clamping lower edge 
section 254. Shield 252 extends into slots 260, to be held in place at 
each end within a sidewall portion 244. Shield 248 also includes, adjacent 
to each end, a spring tab 262, which extends forward to push upward on a 
cylindrical tab 236 of door 26, holding door 12 closed by maintaining 
engagement between slotted tabs 232 and downward-extending tabs 234. 
Door 26 is opened by pushing downward at a ridged gripping surface 263 to 
release slotted tabs 232 from engagement with downward-extending tabs 234, 
and by subsequently rotating the door downward in the direction of arrow 
264. As the door is rotated downward, spring tabs 262 continue to push 
upward on cylindrical tabs 236, aiding in the alignment of these tabs with 
the rearward-extending, horizontal portion of slot 238. Door 26 may then 
be pushed to the rear, into pocket 228, to the position indicated by 
dashed lines 230. The rearward motion of door 26 is limited by a pair of 
stop tabs 266 extending within shield 248 to contact cylindrical tabs 236 
as door 26 is moved fully rearward. As shown in FIG. 19, the edges 268 at 
the right and left ends of door 26 are preferably shaped to prevent inward 
movement of the door unless the door is rotated downward, to be pushed 
straight inward. 
Door 26 is subsequently closed by pulling forward, with cylindrical tabs 
236 being pulled in slots 238. Door 26 is then rotated upward, opposite 
the direction of arrow 264, to be snapped into engagement with tabs 234 
extending downward from housing 242. 
FIGS. 16 through 18 also show the alternate lower bezel 100, including a 
pair of lower doors 100a and 100b. Referring first to FIG. 16, as 
previously discussed in reference to FIG. 6, each door 100a or 100b is 
used to obtain access to a slot 98a in a bracket 98, which is a part of an 
alternate central support structure 97. The metallic enclosure 265 of 
frame 14 includes an upward-extending portion 266, which has an access 
slot 267 adjacent to each slot 98a. An upper edge portion 268 of 
upward-extending portion 266 is clamped between lip portions 256 and 
intervening tab portions 258 of shield 252, thereby assuring electrical 
continuity between shield 252 and frame enclosure 265. 
Referring to FIG. 17, lower door 100a includes a central pivot shaft 269, 
extending toward the center of computer 10, and an outer pivot shaft 270, 
extending away from the center of computer 10. Lower door 100b includes an 
elongated central pivot shaft 270a and an outer pivot shaft (not shown). 
Lower door 100a is pivotally mounted in lower bezel 100, with outer pivot 
shaft 270 being snapped into place to pivot between a pair of flexible 
bearing tabs 271, with central pivot shaft 269 being snapped into place to 
pivot between a flexible bearing tab 272 and a central bearing tab 274. 
Lower door 100b is pivotally mounted in lower bezel 100, with elongated 
central pivot shaft 270a being snapped into place to pivot between a 
flexible bearing tab 272 and a central bearing tab 274, and also between 
another pair of flexible bearing tabs 271. The outer end of door 100b is 
pivotally mounted in a manner similar to the outer end of door 100a. Pivot 
shafts 269, 270, and 270a extend from tabs 278, which in turn extend into 
computer 10 as a part of doors 100a and 100b. This mounting provides for 
the rotation of each door 100a or 100b between a vertical position and a 
horizontal position, as indicated by dashed lines at position 280 in FIG. 
16. 
FIG. 20 is a partial right cross-sectional elevation, taken as indicated by 
section lines XX--XX in FIG. 17, to show the method provided to facilitate 
the manual opening and closing of doors 100a and 100b. A sector gear 282 
is formed at an end of each central pivot shaft 269 and 270a. Both of 
these sector gears 282 engage internal teeth 283 of a lever actuator 284, 
which is pivotally mounted between the two doors 100a and 100b by means of 
an integral pivot shaft 286 extending from each side of actuator 284 to be 
snapped between a central bearing tab 274 and a flexible bearing tab 288. 
Central pivot shafts 269 and 270a are arranged in a coaxial alignment, and 
the two sector gears 282 are rotationally aligned to engage the same 
internal teeth 283. A lever tab 290 of lever actuator 284 extends through 
a slot 292 in the front housing wall 293 of lower bezel 100, providing the 
appearance and manual operating characteristics generally associated with 
an electrical switch. 
Thus, when lever tab 290 is pushed downward to rotate lever actuator 284 in 
the direction of arrow 294, shafts 269 and 270 turn to rotate lower doors 
100a and 100b into the horizontal orientation shown by dashed lines at 
position 280. Similarly, the subsequent rotation of lever actuator 284 
opposite to the direction of arrow 294 rotates doors 100a and 100b into 
the closed position. However, this motion can be prevented by the movement 
of a locking bar 296 into a position stopping the passage of tab 298 of 
actuator 284. 
A multi-functional locking mechanism 299 for moving locking bar 296 to lock 
lower doors 100a and 100b closed, for locking media access door 26 closed, 
and also for locking top cover 12 closed will now be discussed, with 
particular reference being made to FIG. 17 and to FIGS. 21 through 23. 
FIGS. 21 and 22 show the lock 28, with FIG. 21 being a longitudinal 
cross-sectional elevation of the lock, while FIG. 22 is a transverse 
cross-sectional elevation taken as indicated by section lines XXII--XXII 
in FIG. 21. FIG. 23 is a right side cross-sectional elevation, taken as 
indicated by section lines XXIII--XXIII in FIG. 17 to show the 
multifunctional locking mechanism 299 located near the center of frame 
unit 14. 
Referring first to FIGS. 21 and 22, lock assembly 28 is operated by 
inserting a key 300 into a slot 302 within a lock rotor 304, and by 
rotating the rotor 304 within a stator 306, by means of the key, among 
four rotary positions. As key 300 is inserted, its encoded edge 308 
engages a number of tumblers 310, each of which is held against the edge 
308 by means of a compression spring 312. Each tumbler 310 is thus moved 
outward through a distance corresponding to the location of the part of 
encoded edge 308 contacted by the tumbler 310. Each tumbler 310 includes a 
slot 314, with variations in the distance between this slot 314 and the 
points at which the tumblers contact the encoded edge providing the means 
for encoding the lock 28. Thus, if a properly encoded key 300 is fully 
inserted, all of the slots 314 are aligned to allow rotation past a 
barrier 316 extending inward as a part of stator 306. As shown in FIG. 22, 
barrier 316 is divided into three segments, each of which extends inward 
between two of the four slots 318. When the tumblers 310 are aligned with 
one of these slots 318, the key 300 may be inserted and withdrawn. Rotor 
304 can be rotated to bring tumblers 310 out of alignment with a slot 318 
only if a properly encoded key is fully inserted in slot 302. The lock 
assembly 28 is preferably configured so that a key 300 cannot be removed 
from slot 302 unless tumblers 310 are aligned with one of the slots 318. 
This is achieved by assuring that at least one of the tumblers 310 must be 
moved outward during the process of removing key 300. 
In FIG. 17 and in each FIG. 20 through 23, the locking mechanism is shown 
in the first position, in which top cover 12 and all doors 26, 100a, and 
100b are locked. From this position, lock rotor 304 can be rotated in the 
direction of arrow 320 in FIG. 22, and of arrow 322 in FIG. 17, into 
second through fourth positions. In the second of these positions, top 
cover 12 and doors 100a and 100b remain locked, while media access door 26 
is released. In the third of these positions, all doors 26, 100a, and 100b 
are released, while top cover 12 remains locked. In the fourth of these 
positions, top cover 12 and all doors 26, 100a, and 100b are released to 
be opened. 
The lock stator 306 is attached to front housing wall 293, being clamped in 
place, for example, using a collar 324. A flat or keyslot arrangement (not 
shown) is preferably also used to assure the correct orientation of stator 
306 within housing wall 293. A shaft 326 extends rearward into computer 10 
as a part of lock rotor 304. The various locking functions are performed 
by means of a cam 328 rigidly attached to shaft 326. 
Referring to FIGS. 17 and 23, the rear surface of cam 328 includes a spiral 
groove 330. Locking bar 296, which is slidably mounted in a pair of 
slotted tabs 332 extending into system 10 from front housing wall 293, 
includes a tab 334 extending downward and into groove 330. When the 
locking mechanism is in its first and second positions, tab 334 is in a 
portion of groove 330 at its outermost radial location, holding locking 
bar 296 interposed above tab 298 to prevent the rotation of actuator 284 
in the direction of arrow 294 (as shown in FIG. 20). As the locking 
mechanism is rotated between its second and third positions, rotating cam 
328 in the direction of arrow 322, the inward spiral shape of groove 330 
causes the movement of locking bar 296 in the direction of arrow 336, 
releasing tab 298, so that actuator 284 can be moved in the direction of 
arrow 294 to open doors 100a and 100b. As the locking mechanism is further 
rotated between the third and fourth positions, tab 298 remains in a 
portion of groove 330 at its innermost radial location, so locking bar 296 
is held away from tab 298. Thus, doors 100a and 100b are unlocked when the 
locking mechanism is in its third and fourth positions. 
Referring to FIG. 23, cam 328 also includes a peripheral groove 338 
extending around a portion of its cylindrical outer surface. A latching 
bracket 340 includes a tab 342 descending into this groove 338 and a tab 
344 ascending toward media access door 26. Latching bracket 340 is mounted 
to slide in a track 346 within bezel 100, in the rearward direction 
indicated by arrow 348 from the forward position in which it is shown. In 
this forward position, tab 344 blocks the downward motion of media access 
door 26 required to disengage slotted tabs 232 from downward-extending 
tabs 234 (shown in FIG. 16). In this way, media access door 26 is locked 
in a closed position. As the locking mechanism is rotated from its first 
position to its second position, the slope of groove 338 moves locking 
bracket 340 to the rear, so that tab 344 clears door 26, allowing the 
downward motion required to begin the process of opening the door. As the 
locking mechanism is rotated into its third and fourth positions, locking 
bracket 340 remains in its rearward position, with door 26 unlocked. 
Referring to FIG. 17, cam 328 also includes a peripheral cam surface 350. 
Cover latch 29, which is pivotally mounted in lower bezel 100 by means of 
a pin 354, is held against this cam surface by an extension spring 356. 
The tip of latch 29 includes a notch 358, which engages a slot 30 (shown 
in FIG. 3) to hold top cover 12 in a closed position. This slot 30 may be, 
for example, formed in a tab 359 extending from shield 252 (as shown in 
FIG. 23). The top cover is thus locked shut when the lock mechanism is in 
its first through third positions. However, as the lock mechanism is 
rotated between the third and fourth positions, in the direction of arrow 
322, the outward ramped portion 360 of peripheral cam surface 350 moves 
notch 358 in the direction of arrow 336, releasing the engagement of this 
notch 358 with slot 30. In this way, the top cover is locked closed when 
the lock mechanism is in its first to third positions, to be released as 
the locked mechanism is rotated into its fourth position. If top cover 12 
is closed while the lock mechanism is in its fourth position, it remains 
shut but unlocked. If top cover 12 is closed while the lock mechanism is 
in another position, the angle of tip surface 362 moves latch 29 in the 
direction of arrow 336, to be returned subsequently by means of spring 
356, so that the cover 12 is locked down as it is closed. 
Thus, multi-function locking mechanism 299 provides several levels of 
security without requiring several different keys or different locking 
mechanisms. The first level of security prevents both unauthorized use of 
the DASD devices and access to all subassemblies within computer 10. The 
second level of security allows access to the removable media of DASD 
devices, while preventing access to subassemblies within the computer. The 
computer can be fully functional at this level; it can be used for all 
normal functions, even when it is necessary to change the media in DASD 
devices having removable media. However, since access to subassemblies is 
prevented, theft is expected to be reduced. Theft of sensitive data can 
also be protected by software means, such as encryption and the 
requirement for a password to operate some or all system functions. The 
third level of security also permits access to the slots 98a of central 
support structure 97, while continuing to prevent access to subassemblies 
within the computer. The significance of this level of security is 
dependent on the devices mounted in these slots 98a. The fourth level of 
security also permits access to all subassemblies within the computer. 
This level must be accessed for repair and reconfiguration of the 
hardware. While the use of a properly encoded key 300 is required to move 
locking mechanism 299 among these various levels of security, the key 300 
may be removed to leave the mechanism 299 at any such level of security. 
While the door operation and locking aspects of the present invention has 
been shown and discussed in a version of a system including a lower bezel 
100 having lower doors 100a and 100b, it is understood that various 
aspects of this invention can readily be applied to a version of the 
system having lower bezel 14 (shown in FIG. 3) without lower doors. 
Various mechanisms associated with the lower doors, such as lever actuator 
284 (shown in FIG. 20) and locking bar 296 (shown in FIG. 17), would not 
be included in such a version. While the third position of the locking 
mechanism, for releasing the doors 100a and 100b could be omitted, 
reducing the number of slots 318 in stator 306 (shown in FIG. 22), this 
difference from the version described above is not required. Similarly, it 
is possible but not necessary to modify the configuration of cam 328 by 
eliminating groove 330 (shown in FIG. 17). It is a matter of manufacturing 
convenience whether such differences are implemented in two different 
versions of a computer system. 
Significant advantages of the present invention, when compared to the 
background art, arise from the fact that a level of security may be 
selected with the key, which is then removed, causing the system to remain 
at that level of security. For example, the system may be left in a fully 
operational state, providing media access for the DASD devices, without 
exposing the internal subassemblies. The key can be withdrawn and taken 
away at this or any other level of security. This feature contrasts with 
locking mechanisms which leave computers of the background art in either a 
totally locked or a totally unlocked condition. 
Provisions for disengaging the top cover 12 from the frame 14 will now be 
discussed in reference to FIGS. 24 through 26. FIG. 24 is a fragmentary 
underneath cross-sectional plan view, taken as indicated by section lines 
XXIV--XXIV in FIG. 7 to show a hinge coupling 104 used for releasably 
engaging pivot bail 27 with top cover 12. FIG. 25 is a fragmentary right 
side cross-sectional elevation, taken as indicated by section lines 
XXV--XXV in FIG. 24. This mechanism may be used, for example, in changing 
the top cover to a different type, providing even greater configurational 
flexibility. The method chosen for allowing this disengagement requires 
that the system must be unlocked to open top cover 12 before the process 
of disengagement is begun. Thus, the protection afforded by the 
multi-functional locking mechanism 299 is not compromised by the provision 
made for disengaging cover 12 from frame 14. 
Referring to FIGS. 24 and 25, each hinge coupling 104 includes a coupling 
bracket 370 and a coupling spring 372. Coupling bracket 370 is welded to 
metal enclosure 246 of top cover 12 with coupling spring 372 mounted to 
slide between a crossmember 374 formed as a part of coupling bracket 370 
and an adjacent surface of enclosure 246. In this way, coupling spring 372 
is assembled during the welding process as a captive part, which can be 
moved back and forth, but which cannot be removed. Pivot bail 27 is 
pivotally mounted between a downward curved bracket portion 376 of 
coupling bracket 370 and a downward curved spring portion 378 of coupling 
spring 372. Frictional engagement between the coupling spring 372 and the 
surfaces on which it slides is ensured by curving a central portion of the 
coupling spring as generally indicated by dashed line 380 before the 
welding process. Thus, frictional engagement prevents the motion of 
coupling spring 372 in the absence of externally applied forces. 
Pivot bail 27 is disengaged from the hinge coupling 104 by applying 
pressure to spring tab 382 in the direction of arrow 384, causing the 
deflection of spring tab 382 in the direction of arrow 386, along with the 
sliding of coupling spring 372 in the direction of arrow 388. In this way, 
coupling spring 372 is moved into the position indicated by dashed lines 
at position 390, opening the space between downward curved spring portion 
378 and downward curved bracket portion 376 to release bail 27 as 
indicated by dashed lines at position 392. 
Coupling bracket 370 includes a tab 394 extending toward an opening 396 of 
an adjacent pocket 398 formed in coupling spring 372. If an attempt is 
made to move the spring 372 in the direction of arrow 388 without exerting 
a downward force on tab 382, pocket 398 is moved over tab 394, so that 
this motion in the direction of arrow 388 is limited to a travel distance 
insufficient to release pivot bail 27. Thus, pulling the outward extending 
portion 400 of coupling spring 372 does not result in releasing bail 27 
from the coupling 104. To release the bail 27, it is therefor necessary to 
open top cover 12, having released latch 29 by means of lock 28 (shown in 
FIG. 23), so that a downward force may be applied to deflect spring tab 
382 in the direction of arrow 386. In this way, the ability of the lock 
mechanism to prevent access to various subassemblies within system unit 10 
is maintained. 
Hinge coupling 104 may be engaged with pivot bail 27 essentially by 
reversing the procedure described above. With coupling spring 372 in the 
open position indicated at dashed lines 390, pivot bail 27 is introduced 
into the opening provided between downward curving spring portion 378 and 
downward curving bracket portion 376. Coupling spring 372 is then slid in 
the direction opposite arrow 388, as spring tab 382 is pulled downward to 
cause deflection in the direction of arrow 386. 
In order to disengage the top cover 12 from frame unit 14, travel limiting 
linkage 110, which has been described in reference to FIGS. 7 and 8, is 
disengaged from top cover 12. FIG. 26 shows a pin 115 configured to 
provide for this disengagement. This pin 115 includes a solid portion 406 
extending through a hole in metal enclosure 246 of top cover 12 to a rivet 
head 408. Pin 115 also includes a hollow portion 410 extending inward to 
engage a pivot hole 412 in upper link 114. Mutually perpendicular slots 
413 extend along the length of hollow portion 410, providing flexibility 
by dividing this portion 410 into four sections. Pin 115 is fastened to 
metal enclosure 246 by forming a shoulder portion 414 at an end of hollow 
portion 410. An enlarged portion 416 is also formed at a tip of hollow 
portion 410, providing a surface over which upper link 114 is snapped to 
be engaged with, or released from, pin 115. Thus, the top cover 12 must be 
opened, having been unlocked, for the removal of link 114 from pin 115, by 
sliding the link inward on the pin. 
While the preceding discussion has been related to the releasable 
engagement of pivot bail 27, it is understood that hinge coupling 104 
could be used with equal effectiveness to establish the releasable 
engagement of another type of pivot pin structure, such an a hinge pin 
fastened directly to a frame for pivotally mounting a cover. 
Referring again to FIG. 3, a long gap, or seam is presented around the 
interface between top cover 12 and frame 14. Since both metal enclosure 
246 of top cover 12 and metal enclosure 265 of frame 14 are used to 
provide shielding for minimizing the emission of electromagnetic energy at 
radio frequencies, which could otherwise interfere with communication 
signals, it is necessary to provide a number of electrical contact points 
spaced along this gap. Naturally, this shielding is effective only when 
the top cover 12 is closed (as shown in FIG. 1), but the top cover should 
be closed for system operation. Some of these contact points are formed at 
the interface between shield 252 and frame metal enclosure 265, as 
described above in reference to FIG. 16. Others of these contact points 
are formed through the use of flexible contact segments 31, which extend 
along a downward-extending skirt portion 420 at each side of cover metal 
enclosure 246. At each side, the skirt portion 420 fits inside an adjacent 
side portion 424 of frame enclosure 265, with electrical contact being 
effected between the convex-curved portion of each contact segment 31 and 
an adjacent inner surface of side portion 424. While the distance required 
between adjacent contact points depends in part on a number of operating 
parameters, such as the clock frequencies of computer 10, this method of 
forming flexible contact segments 31 can readily be used to produce 
contact spacings of 0.75 to 1.5 inch as typically required. Similarly the 
spring tabs 258 (shown in FIGS. 16 and 18), which extend as portions of 
shield 252 to contact frame metal enclosure 265, may be placed as close 
together as necessary for effective shielding. 
The method used to provide these flexible spring segments 31 will now be 
explained with reference being made to FIGS. 27 and 28. FIG. 27 is a 
fragmentary right side elevational view, showing the lower front corner 
portion of top cover 12. FIG. 28 is a fragmentary front elevational view, 
taken through the center of a contact segment 31, as indicated by section 
lines XXVIII--XXVIII in FIG. 27. Referring first to FIG. 27, the 
individual contact segments 31 are formed as "T"-shaped portions of a 
spring strip 422 extending along each skirt portion 420. In the assembly 
process, spring strip 422 is first fit into a number of essentially 
triangular apertures 424 in skirt portion 420, with the widened end 426 of 
each contact segment 31 fitting through an aperture 424. Referring to FIG. 
28, the "U"-shaped lower portion 428 of spring strip 422 is then welded 
along the lower edge of skirt portion 420. The engagement of each widened 
portion 426 within an aperture 424 serves to maintain the convex shape of 
each contact segment 31. 
As shown in FIG. 29, specialized mounting bracket configurations may 
alternately be attached to slotted bracket 71, by screws 73 in place of 
blank brackets 77, (shown in FIG. 3) to provide additional types of I/O 
ports or solid-state removable media. For example, a feed-through mounting 
bracket 450 includes a pair of connectors 452, which are electrically 
connected by wires 454 and a connector 456 to a circuit card 458. 
Connectors 452 carry electrical signals into or out of computer 10 through 
a slot 74 in bracket 71. A bracket 450 of this kind may be used, for 
example, to connect audio signals with circuits in computer 10. 
A socket 460, built in accordance with the standards of the Personal 
Computer Memory Card Industry Association (PCMCIA) is similarly mounted to 
slotted bracket 71, by means of a socket mounting bracket 462. In 
accordance with well known standards, socket 460 removably accepts a pair 
of circuit cards, which may be manually inserted into upper and lower 
slots in the direction of arrow 466. Socket 460 includes a number of 
terminal pins (not shown), which extend into sockets in an end of card, 
making electrical contact with terminal springs (not shown) within card 
464. Additional mechanisms (not shown), associated with socket 460, are 
further configured in accordance with well known standards to provide 
additional features. As a card 464 is inserted, an ejection mechanism (not 
shown) is conditioned to facilitate the subsequent removal of the card 
464. When a pushbutton 468 is depressed, in the direction of arrow 466, 
the ejection mechanism is released to push an adjacent card 464 partially 
outward, in the direction opposite arrow 466, thereby facilitating manual 
removal of the card. The terminal pins within socket 460 are electrically 
connected to a circuit card 458 by means of a flexible circuit cable 470 
and connector 472. Circuit card 458 may be, for example, the system planar 
board 36 or an option card 62 (shown in FIG. 3). 
Cards configured to fit into a PCMCIA-type socket 460 are generally 
available, containing random-access memory, read-only memory with a stored 
program, or I/O adapter logic. Cards having random-access memory can be 
used to expand system memory, while cards having read-only memory can be 
used as a source of external programs, in place of diskettes. Cards with 
I/O adapter logic may have cables to peripheral devices extending from or 
otherwise connected to their outward extending edges 476. 
Referring to FIG. 30, alternate or additional means for mounting a 
PCMCIA-type socket 460 to removably accept cards 464 may be provided by 
attaching a socket frame 478 within the right front corner of frame 14. An 
access door 480 is provided in lower front bezel to permit access to 
removable cards 464 and to card ejection pushbuttons 468. This access 
occurs under an overextending bracket assembly 95 holding speaker 95a and 
switches and indicators 95b. A flexible cable 484 extends under cooling 
fan 34 for connection to planar board 486 by means of a connector 36. As 
described above in reference to FIG. 3, cooling fan 34 is mounted in a 
position spaced above an adjacent inner surface 52 of frame 14, providing 
a space suitable for cable routing. 
An alternative linkage 490 for supporting top cover 12 in a raised position 
will now be discussed, with particular reference being made to FIGS. 31 
and 32. This linkage 490 is an alternative to the linkage 110 previously 
discussed in reference to FIGS. 7 and 8. FIG. 31 is a partial elevational 
view showing the alternative linkage 490 extending between frame 14 and 
top cover 12, with top cover 12 in an open position for servicing or 
reconfiguring system 10. FIG. 32 is an exploded isometric view of a 
friction brake and detent mechanism 492 used to stabilize the linkage 110 
with top cover 12 in its open position. 
Referring to FIG. 31, an alternative linkage 490, fastened at each side 
between frame 14 and top cover 12 includes a lower link 494 and an upper 
link 496, pivotally joined through a friction brake and detent mechanism 
492. A lower tab 498 of lower link 494 is displaced outward for pivotal 
attachment to a pin 499 extending inward from a sidewall 500 of frame 14. 
Upper link 496 is pivotally attached to upper cover 12 by a hollow pin 
115, which has been discussed in reference to FIG. 26. Pivoting bail 27 is 
pivotally attached to frame 14 and to top cover 12, being used as 
previously described with reference to FIGS. 2, 7, and 8. 
As top cover 12 is pivoted downward, the pivotal connection at friction 
brake 492 is moved in the direction of arrow 120. In this way, linkage 490 
is folded forward to allow the free flow of cooling air through slots 46 
in upper cover 12. A notch 508 in upper cover 12 allows this cover 12 to 
be pivoted downward over the outward spaced tab portion 498 of lower link 
494 at each side of frame 14. This notch 508 does not extend upward into 
the portion of top cover 12 which is externally visible when top cover 12 
is closed. 
Referring to FIG. 32, lower link 494 and upper link 496 are pivotally 
attached by means of a pivot screw 510, which includes a hexagonal 
shoulder 512, a round shoulder 514, and a threaded portion 516. When these 
items are assembled, hexagonal shoulder 512 engages upper link 496 by 
means of a hexagonal aperture 518, while also engaging a bellville spring 
washer 520 and a detent plate 522 by extending through central hexagonal 
apertures 524 and 526, respectively. Round shoulder 514 of pivot screw 510 
extends through hole 528 in thrust plate 530, through hole 532 in lower 
arm 494, and through hole 534 in thrust washer 536. Threaded portion 516 
of pivot screw 510 engages a nut 538. 
Thus, the opening or closing of top cover 12 (shown in FIG. 31) results in 
the rotational motion of upper link 496 relative to lower link 494. 
Bellville spring washer 520 and detent plate 522 are constrained by 
hexagonal shoulder 512 to turn with upper link 496. Thrust plate 530 is 
held against a thrust surface 540 of lower link 494, being constrained 
from rotation by a pair of tabs 542 held in slots 544 extending outward 
from thrust surface 540. As nut 538 is fastened onto threaded portion 516 
of pivot pin 510, the compression of bellville spring washer 520 holds 
thrust plate 522 against thrust washer 530, with contact being made 
particularly between a pair of dimples 546 in detent plate 522, directed 
toward thrust plate 530. When top cover 12 (shown in FIG. 31) is in its 
fully open position, each dimple 546 extends into a corresponding detent 
hole 548 in thrust washer 530, providing a tendency to hold top cover 12 
fully open. 
As top cover 12 is opened or closed, relative rotation occurs at a first 
interface between detent plate 522 and thrust plate 530 and at a second 
interface between nut 538 and lower link 494. Detent plate 522 and thrust 
plate 530 are preferably composed of hardened steel, while thrust washer 
536 is preferably composed of a plastic resin having lubricity, such as an 
acetal material. A number of widely known techniques for locking nut 538 
in place on threaded portion 516 may be employed to prevent the loosening 
of nut 538 with the opening and closing of linkage 490. Such techniques 
include the adhesive fastening of nut 538 to threaded portion 514 and the 
provision of an elastomeric insert within the threads of nut 538 or within 
threaded portion 516. 
A motion limiting surface 550 of lower link 494 and a similar motion 
limiting surface 552 of upper link 496 are offset to contact one another 
when top cover 12 is fully opened, preventing further relative rotation of 
links 494 and 496. This position is held by means of the detent function 
provided by dimples 546 extending into adjacent holes 548. Various 
parameters, such as the force provided by the compression of bellville 
spring washer 520, the shape of dimples 546, and the angle to which links 
494 and 496 are allowed to open before contact occurs between motion 
limiting surfaces 550 and 552, may be adjusted to provide either a 
mechanism allowing the closure of top cover 12 applying pressure to top 
cover 12, or alternately a mechanism preventing the closing of top cover 
12 until a force is applied to linkage 492 in the direction of arrow 120. 
FIG. 33 is a fragmentary isometric view of an alternative mechanism for 
attaching planar board 36 to frame 14, thereby providing an alternative to 
the mechanism previously described in relation to FIGS. 11 through 13. 
Thus, alternate means for engaging a mounting screw 188, used in the 
attachment of a planar board 36 to frame 14, include a formed nut 560, a 
formed spacer 562, and an attachment plate 564. Spacer 562 includes a 
flange 566 and a tapered hexagonal upstanding portion 568. Similarly, nut 
560 includes a flange 566 and a tapered hexagonal upstanding portion 572, 
which fits inside upstanding portion 568 of spacer 562 to provide a 
threaded surface 573 for engaging screw 188. Attachment plate 564 includes 
a hexagonal aperture 574 at each location where nut 560 may be placed for 
fastening a planar board in place. Hexagonal aperture 574 is used both for 
locating nut 560 and for preventing its rotation when screw 188 is 
subsequently tightened to fasten planar board 36 in place. Spacer 562 also 
includes a number of lanced tabs 578, which snap into corresponding slots 
580 of nut 560 to hold these parts together when they are assembled at a 
location defined by an aperture 574. 
The process of attaching planar board 36 to frame 14 begins with the 
assembly of a number of spacers 562 to nuts 560 extending through 
hexagonal apertures 574 in positions corresponding to locations of 
mounting holes in planar board 36. In the manner previously described in 
reference to FIG. 11, attachment plate 564 may include several patterns of 
apertures 574 for attaching several different planar boards. The assembly 
thus formed is attached to frame 14 by means of a number of screws 582 
engaging standoffs 584 extending upward from frame 14. Planar board 36 is 
then installed, with various screws 188 engaging various nuts 560. The 
configuration of nuts 560 and spacers 562 may subsequently be changed, if 
necessary, by removing plate 564 from frame 14, and by moving the nuts and 
spacers around as required. This method may be used, for example, to 
facilitate upgrading computer 10 by installing another kind of planar 
board. 
The preceding discussion has been directed to particular examples of the 
present invention using the ISA bus as an interface to cards, such as 
option cards 62 (shown in FIG. 3) or short option cards 94 (shown in FIG. 
5). Thus, the connectors 63 on riser card 64 (shown in FIG. 4) are of a 
type compatible with cards configured according to standards for the ISA 
bus interface. Similarly, slotted bracket 71 provides a mechanical 
interface compatible with the attachment of the cards configured according 
to standards associated with the use of the ISA bus. In turn brackets 72 
(shown in FIG. 3), and the specialized brackets 450 and 462 (both shown in 
FIG. 29) provide a mechanical interface compatible with bracket 72, and 
also with mounting means provided in various other systems using the ISA 
bus. 
As shown in FIG. 34, concepts of the present invention can be applied with 
equal facility, for example, to a system configured to use the IBM 
"MicroChannel" bus (a registered trademark of International Business 
Machines Corporation). In this example, a riser card 594 includes a number 
of connectors 596 configured for the attachment of standard option cards 
598 using the MicroChannel bus. These connectors 596 are different from 
the previously described connectors 63 in a number of ways, including the 
use of a 0.050-inch contact spacing in place of the 0.100-inch contact 
spacing of connectors 63. A different planar board 600, providing signals 
for the MicroChannel bus at an interface connector 602, into which riser 
card 594 is plugged, is also used in this example. 
Option card 598 includes provisions for electrical grounding which are 
typically used in systems with the MicroChannel bus. A slotted mounting 
structure 604 is provided at the back of the computer system, with 
features for providing a grounding and mounting interface for standard 
cards, such as option card 598. This mounting structure 604 is preferably 
a die cast metallic structure, which may be mounted in the computer in 
place of slotted bracket 71, having similar means for attachment within 
the framework of the computer. Since mounting structure 604 is used to 
provide electrical grounding for option cards 598, suitably grounding is 
preferably provided for structure 604 through the framework of the 
computer, or through additional grounding means. 
A flexible grounding bracket 606 is attached as a part of the assembly of 
card 598 using rivets 608. Card assembly 598 is installed by sliding in 
the direction of arrow 610, with grounding bracket 606 sliding into an 
elongated slot 612 of mounting structure 604. As this occurs, a pair of 
tabs 614 of grounding bracket 606 slide into slots 615 of mounting 
structure 604, and with a number of cantilever spring portions 616 of 
flexible grounding bracket 606 effecting electrical grounding by 
contacting mating surfaces 618 extending along each side of elongated slot 
612. Slotted end 620 of grounding bracket 614 slides along an outer 
surface (not shown, but opposite inner surface 621) of mounting structure 
604, with slot 622 passing over a threaded stud 624, extending outward in 
the direction of arrow 626. Additional electrical grounding is provided by 
contact between flexible tab 628 of grounding bracket 606 and an adjacent 
inner surface 630 of mounting structure 604. Contact tab 632 of card 598 
is simultaneously inserted into the slots 634 of a connector 596, with 
conductive pads (not shown) on contact tab 632 making electrical contact 
with spring contacts (not shown) within connector 596. Card assembly 598 
is subsequently held in place by tightening a nut 636 on the stud 624, 
clamping slotted end 620 of grounding bracket 606 in place. Nut 636 is 
preferably of a captive type, which cannot be removed from stud 624, and 
which, having a knurled surface, can be tightened by hand. 
As also shown in FIG. 34, a socket 460, built in accordance with PCMCIA 
standards as previously discussed in reference to FIG. 29, is provided 
with alternate means for attachment in a structure, such as mounting 
structure 604, configured to accept option cards for attachment to the 
MicroChannel bus. Thus, socket mounting bracket 638 is formed to include a 
slotted tab portion 640 and a pair of mounting tabs 642. A flexible 
grounding bracket 644, attached to socket mounting bracket 638 by means of 
rivets 646, includes features of grounding bracket 606, such as cantilever 
spring portions 616 and a flexible tab 628. 
When the socket assembly thus formed is installed in a slot 612 by sliding 
in the direction of arrow 610, electrical grounding is effected as 
described above, through contact between cantilever spring portions 616 
and flexible tab 628 of grounding bracket 644. Socket assembly 630 is 
subsequently held in place, and a ground connection capable of carrying 
high currents is established with slotted tab portion 640, by tightening a 
nut 636 on a threaded stud 624. 
As further shown in FIG. 34, riser card 394 includes an electrical 
interface for a PCMCIA-type socket at a connector 650, to which socket 460 
is attached by means of a mating connector 652 and a flexible cable 654. 
The application of various aspects of the present invention to a personal 
computer having additional capabilities achieved through the use of an 
enlarged top cover will now be discussed in reference to FIGS. 35 through 
37. FIG. 35 is an isometric view of this expanded personal computer 660 
with the enlarged top cover 662 in an open position. FIG. 36 is a partial 
right cross-sectional elevation of computer 660, with top cover 662 in a 
closed position, taken along section lines XXXVI--XXXVI in FIG. 35, in the 
manner of previously-discussed FIG. 16, showing particularly the 
arrangement of access doors and of the space adjacent to these doors. FIG. 
37 is a partial cross-sectional elevation showing a sliding link 690 used 
in locking media access door 26, taken along section lines XXXVII--XXXVII 
in FIG. 35. 
Referring first to FIG. 35, an enlarged top cover 662 may be installed in 
place of top cover 12 (shown, for example, in FIG. 6). Specifically, the 
sides 664 of the top cover enclosure 665 and the upper bezel 668 of top 
cover 662 are extended downward to provide space under DASD devices 88 and 
93, which are attached to the top cover 662 by means previously described 
in reference to FIGS. 9 and 10. The media access door 26 of previous 
configurations fits into an opening in the upper portion of front bezel 
668, and two intermediate access doors 670 are pivotally mounted in 
openings below door 26. This enlarged cover 662 is mounted to the frame 
unit 14 of previously discussed versions of the computer. Frame 14 
includes a front bezel 100 having a pair of pivotable doors 100a and 100b. 
The same means for pivotable attachment, consisting of travel limiting 
linkages 110 and of pivoting bail 27, which have been described in 
reference to FIGS. 7 and 8, are used. Since the attachment positions of 
pivoting bail 27 remain in the location previously described for computer 
10, despite the larger top cover 662, a rear panel 672 is added to the 
metal enclosure 665 of top cover 662. Previously described means are used 
for the releasable attachment of linkages 110 and of pivoting bail 27. A 
pair of hinge couplings 104, which are described above in reference to 
FIGS. 24 and 25, are attached to rear panel 672. Linkages 110 are attached 
to enlarged top cover 662 by means of snapfit couplings 115 as previously 
described in reference to FIG. 26. 
The benefits of this approach are best seen by comparing FIGS. 16 and 36, 
which are, respectively, right side cross-sectional elevations of computer 
10 (shown in FIG. 3), with the conventional top cover 12, and of computer 
660 (shown in FIG. 35), with an enlarged top cover 662. In computer 660, 
additional space is provided below shield 674, which is similar to shield 
252, except for a downward-extending portion 676, which engages the upper 
edge portion 268 of metal enclosure 265 of frame 14. Thus, shield 674 
provides a place for storing media access door 26 in an open, horizontal 
position, as indicated at dashed lines 230, and as previously described in 
reference to FIG. 16. In computer 10, the space between transverse duct 38 
and shield 252 is limited so that "H"-shaped central support structure 97 
has room for only a single slot 98a on each side of central support member 
99 (also shown in FIG. 6). On the other hand, in computer 660, there is 
enough distance between transverse duct 38 and shield 674 to allow space 
for both an upper slot 678 and a lower slot 680 on each side of central 
support member 681 of enlarged "H"-shaped central support structure 684. 
Downward-extending portion 676 includes a slot 685 to provide access to 
each upper slot 678. 
Referring again to FIG. 35, these slots 678 and 680 in front slotted 
bracket 682 of central support structure 684 may be used for mounting the 
card bracket 72 of a short option card 94 or for mounting the a 
specialized mounting bracket configuration, such as one of the 
configurations discussed above in reference to FIG. 29. For example, 
socket mounting bracket 462 can be used to mount a PCMCIA-type socket 460, 
with a cable 470 extending to a be connected to a riser card (not shown) 
within central support structure 684. 
In both the enlarged version of FIG. 35 and the smaller version of FIG. 6, 
this type of mounting for socket 460 is feasible and particularly 
desirable, since the cards 464 inserted into the socket 460 and the 
associated card ejection buttons 468 are accessable from the front of the 
computer with the appropriate doors open. Thus, these advantages are 
achieved either by attaching socket mounting bracket 462 to front slotted 
bracket 682 of computer 660 or to front slotted bracket 98a of computer 10 
(shown in FIG. 6). 
Referring again to FIG. 36, lower slots 680 are accessed through lower 
doors 100a and 100b, while upper slots 678 are accessed through 
intermediate doors 670. These doors 670 are mounted to rotate between a 
closed (vertical) position and an open (horizontal) position, as indicated 
at position 686 by dashed lines, in the manner of lower doors 100a and 
100b, as previously described in reference to FIGS. 16, 17, and 20. A 
second lever actuator 284 (shown in FIG. 35), between these doors 670 in 
top cover 662 is added to provide means for manually opening and closing 
doors 670. 
A separate locking mechanism is not needed for intermediate doors 670. As 
these doors are pivoted open, their lower edges traverse a curved path 688 
as indicated by a dashed line, contacting the upper edges of doors 100a 
and 100b if these doors 100a and 100b are closed. Thus, doors 100a and 
100b must be opened before doors 670 can be opened. In this way, the use 
of lock 28 to determine whether doors 100a and 100b can be opened is 
extended to provide a similar determination relative to doors 670. 
The use of a cam 328 rotated by a lock 28 to move a locking bracket 340 has 
been discussed in reference to FIG. 23. Since the same frame unit 14 is 
used in computer 660, the multi-function locking mechanism 299 is also 
available in computer 660. In computer 10, when locking bracket 344 is 
moved in the direction of arrow 348, access door 26 can be moved downward 
for opening. When locking bracket 344 is returned in the direction 
opposite arrow 348, the downward motion required to begin the process of 
opening the door is blocked. 
Referring to FIG. 37, in computer 660 (shown in FIG. 35) a sliding link 690 
is added to prevent downward motion of door 26 from its position in cover 
bezel 668. This link 690, which is arranged to slide vertically in a track 
692, includes a tab 694 extending under door 26 to block downward motion 
of the door and an inclined surface 696 engaging locking bracket 344. When 
locking bracket 344 is held in the direction opposite arrow 348, the 
downward motion of sliding link 690, resulting from an attempt to open 
door 26, is prevented by contact between inclined surface 696 and locking 
bracket 344. When locking bracket 344 is moved in the direction of arrow 
348, this motion is allowed to occur. When locking bracket 344 is returned 
in the direction of arrow 348, the angle of inclined surface 696 returns 
sliding bracket 694 upward. 
The preceding discussion has described a number of versions of the present 
invention having means for pivotally mounting a top cover along rear edges 
of the top cover and of the frame unit. However, as shown in FIGS. 38 and 
39, the present invention may alternately be applied to a personal 
computer 700 in which a top cover 702 is pivotally mounted along an 
attachment side 704, extending from front to rear of a frame unit 706. 
FIG. 38 is a front elevational view of the computer 700 with its top cover 
702 rotated upward into the position required for service and 
reconfiguration. FIG. 39 is a partial cross-sectional right side 
elevational view taken as indicated by section lines XXXIX--XXXIX in FIG. 
38. In the example of FIG. 38, the right side of computer 700 is used as 
the attachment side 704. The following discussion describes the example of 
computer 700, with items having similar functions and characteristics as 
those previously described being accorded like reference numerals. 
Referring first to FIG. 38, a top cover 702 is pivotally attached along an 
upper edge of attachment side 704 by means of a pair of "U"-shaped formed 
hinge rods 707 fastened to the side 704, for example, by welding. Top 
cover 702 is preferably mounted to pivot on hinge rods 707 by means of a 
pair of releasable hinge couplings 104, which have been described in 
detail referring to FIGS. 24 and 25. In this way, top cover 702 can be 
easily removed after it is opened. A travel-limiting linkage 110, which 
has been described in detail referring to FIGS. 7 and 8, is also used to 
stop the opening rotation of top cover 702. This linkage 110 of computer 
700 is in an inverted relationship with the linkage 110 of computer 10, so 
that contact between tab 118 and stopping surface 121 prevents motion in 
the direction of arrow 708, away from the pivot axis determined by hinge 
rods 707, instead of in the direction of arrow 120 (as shown in FIG. 8) 
toward the pivot axis determined by upper rod portion 27 of pivot bail 27 
in computer 10. Thus, as upper cover 702 is closed, linkage 110 folds 
toward the pivot corner, in the direction opposite arrow 708, instead of 
away from the pivot corner, in the direction opposite arrow 120 (as shown 
in FIG. 8). In this way, an adjacent area 710, in which a DASD unit may be 
placed in engagement with a channel 86 of top cover 702, is not 
compromised by a need to accept the folding of linkage 110 as top cover 
702 is closed. The offset of central pivot 116 from a line between upper 
pivot 115 and lower pivot 113 (shown in FIG. 8) is retained to provide a 
means for holding the top cover open (as described in reference to FIGS. 7 
and 8). After top cover 702 is fully open, it is necessary to push the 
central portion of linkage 110 in the direction opposite arrow 708 to 
begin the process of closing top cover 702. 
Continuing to refer to FIG. 38, various features of computer 10 are 
retained in computer 700. For example, a central support structure 79 
includes a riser card 64, which is plugged into a planar board 36 at a 
planar board connector 65 (as shown in FIG. 4). Riser card 64 includes a 
number of attached connectors 63 into which option card assemblies 62 may 
be plugged. Central support structure 79 includes a slotted bracket 71, to 
which brackets 72 of card assemblies 62 are attached by means of screws 
73. Top cover 702 includes a bracket 124, with slotted channels 86, 
internally attached by welding, to which DASD storage devices 88 and 93 
may be in turn attached in the manner previously discussed in reference to 
FIGS. 9 and 10. 
Referring to FIG. 39, like computer 10, computer 700 includes a media 
access door 26 which is manually movable between a vertical closed 
position and a horizonal open position indicated by dashed lines at 
position 230. However, in computer 700, the shield 712 forming a pocket 
for door 26 in its open position does not move upward with top cover 702 
as this cover is opened. Metal enclosure 714 of frame unit 706 includes an 
upstanding portion 716 to which shield 712 is attached. Metal enclosure 
718 of top cover 702 includes a downward extending portion 720, which 
engages a front lip 722 and a number of spring tab portions 724 of shield 
712. Slotted tabs 232 of door 26 engage a downward formed lip portion 726 
of cover enclosure 718 to hold door 26 in a closed position. 
Referring to FIGS. 38 and 39, a rotary lock 28 with an attached cam 728 is 
used to provide the functions of locking top cover 702 and media access 
door 26 in closed positions. In the general manner previously discussed in 
reference to FIG. 23, as lock 28 is rotated with an inserted encoded key, 
a sliding bracket 730 is moved by a groove 732 between a forward position 
in which downward motion of door 26 is permitted to a rearward position in 
which such motion is permitted. Since shield 712 remains in place as top 
cover 702 is opened, a connecting link 734 is used to transmit the motion 
provided by a peripheral surface 736 of cam 728 between a cam follower 738 
pivoted at a pin 740 and a cover latch 742 pivoted at a pin 744. Top cover 
702 includes a latching bracket 748, which engages latching surface 750 of 
cover latch 742 when lock 28 is rotated to allow the motion of this latch 
742 in the direction of arrow 752. Cam follower 738 is held against 
peripheral cam surface 736 by means of an extension spring 754. 
An advantage of relative simplicity is achieved by employing the methods 
shown in FIGS. 38 and 39, in that a simple pivot along the upper edge of 
frame attachment side 704 is used in the attachment of top cover 702. That 
is, a bail pivotally mounted to both the frame and cover, as described in 
reference to FIGS. 2, 7, and 8, is not required. This simplicity is not 
simply due to pivoting the cover on the side instead of in the back; it is 
due to the fact that, in the computer of FIGS. 38 and 39, the central 
attachment structure 79 can be removed without moving the top cover with 
attached DASD devices away from the frame 706. However, even in this 
configuration, a pivotable bail of the type shown in FIGS. 2, 7, and 8 
would possess some benefits in facilitating the removal of the power 
supply (not shown, but placed in the location of power supply 32 of FIG. 
3). Also, it is understood that a rearrangement of internal components 
could result in a configuration having a top cover pivoted along the rear 
without a requirement for the cover to be moved away from the frame as it 
is opened. 
While the invention has been described in its preferred forms or 
embodiments with some degree of particularity, it is understood that this 
description has been given only by way of example and that numerous 
changes in the details of construction, fabrication and use, including the 
combination and arrangement of parts, may be made without departing from 
the spirit and scope of the invention.