Abstract:
A portable information handling system, user interface components thereof, and methods of user control interface and assembly are disclosed. In one embodiment a keyboard assembly, including a large plurality of contacts for a keyboard matrix, connects directly to a palmrest assembly. The palmrest assembly includes a keyboard controller, which decodes keystrokes and then passes the decoded keystrokes to, e.g., an I/O controller on the motherboard of the portable information handling system. This results in greatly improved layout and usage of the motherboard routing spaces, improved reliability, and simplified assembly.

Description:
BACKGROUND 
     The description herein relates to portable information handling systems and the keyboard interconnects for such systems. 
     As the value and use of information continue to increase, individuals and businesses seek additional ways to process and store information. One option available to users is information handling systems. An information handling system (IHS) generally processes, compiles, stores, and/or communicates information or data for business, personal, or other purposes thereby allowing users to take advantage of the value of the information. Because technology and information handling needs and requirements vary between different users or applications, IHSs may also vary regarding what information is handled, how the information is handled, how much information is processed, stored, or communicated, and how quickly and efficiently the information may be processed, stored, or communicated. The variations in IHSs allow for IHSs to be general or configured for a specific user or specific use such as financial transaction processing, airline reservations, enterprise data storage, or global communications. In addition, IHSs may include a variety of hardware and software components that may be configured to process, store, and communicate information and may include one or more computer systems, data storage systems, and networking systems. 
     Portable IHSs, such as “laptop” or “notebook” computers, generally place all or most of the components of the system in a single chassis of small enough dimensions and weight to be conveniently carried in a briefcase or similarly sized carrying case. 
     SUMMARY 
     A portable IHS comprises a housing enclosing a motherboard, a palmrest assembly coupled to the housing and comprising a keyboard controller, and a keyboard assembly coupled to the palmrest assembly such that the keyboard controller receives keystroke signals from the keyboard assembly. A first bus couples the keyboard controller to the motherboard through the palmrest assembly, with the keyboard controller transmitting decoded keystrokes to the motherboard over the bus. 
     In another aspect of the disclosure, a computer palmrest assembly comprises a circuit board, a keyboard controller mounted to the circuit board, and a connection point to receive a keyboard assembly. The connection point has a plurality of electrical connections connected through the circuit board to the keyboard controller. The palmrest assembly further comprises a first connector to pass decoded keystroke information from the keyboard controller to another device located off the palmrest assembly. 
     In yet another aspect of the disclosure, a keyboard comprises a rigid lower frame having a connection tab along its bottom edge for mechanical connection to a palmrest assembly, and a conductor matrix overlying the rigid frame and defining conductor crossing points substantially aligned with key locations on the keyboard. The conductor matrix comprises extensions of the matrix conductors onto the connection tab to form a plurality of contacts for electrical connection of the keyboard to the palmrest assembly. 
     In still another aspect of the disclosure, a diagnostic system for a portable computer comprises a motherboard having a first I/O controller, a palmrest assembly having a second I/O controller, and a bus connection linking the first I/O controller to the second I/O controller through the motherboard and palmrest assembly. A keyboard assembly connects to the palmrest assembly. A loopback circuit on the palmrest assembly and keyboard assembly allows the second I/O controller to test the continuity of the connection between the keyboard assembly and the palmrest assembly. 
     Also disclosed is a method of coupling a keyboard assembly to a portable IHS. The method comprises assembling a keyboard connector into the palmrest assembly of a portable IHS, and inserting a substantially rigid keyboard assembly connector tab, integral to a keyboard assembly and having electrical connections for the keyboard assembly, into the keyboard connector of the palmrest assembly as part of a process of aligning the keyboard assembly in its final position in the IHS. The keyboard assembly is secured to the IHS. 
     The disclosure also describes a method of inputting keystroke information to a portable IHS. The method comprises translating user keystrokes on a keyboard assembly into electrical signals, transmitting the electrical signals through a connector from the keyboard assembly to a palmrest assembly comprising a keyboard controller, and decoding the electrical signals in the keyboard controller into decoded keystrokes. The decoded keystrokes are transmitted over a first serial bus to a motherboard located in the portable IHS. 
     One other aspect of the disclosure relates to a portable IHS comprising a housing, a motherboard located within the housing, a pointing device assembled to the housing to allow user pointing inputs, and a keyboard assembled to the housing to allow user keyboard inputs. The system includes at least one I/O controller, located off the motherboard, to decode the user pointing inputs and decode user keyboard inputs, and at least one serial bus to communicate the decoded user pointing inputs and the decoded user keyboard inputs to the motherboard. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a block diagram illustrating an embodiment of an IHS. 
         FIG. 2  illustrates the external configuration of an embodiment of a portable IHS. 
         FIG. 3  contains an exploded view of the built-in user controls of an embodiment of a portable IHS, and their interconnections to the motherboard. 
         FIG. 4  shows the electrical connections and controllers for the built-in user controls of an embodiment of a portable IHS. 
         FIG. 5  shows the electrical connections and controllers for the built-in user controls of an embodiment of a portable IHS. 
         FIG. 6  contains an exploded view of the built-in user controls of the embodiment of  FIG. 5 . 
         FIG. 7  illustrates a detailed exemplary connection detail for a palmrest assembly according to an embodiment. 
         FIG. 8  shows details of a keyboard assembly according to an embodiment. 
         FIGS. 9 ,  10 , and  11   a - 11   c  depict assembly details for a portable IHS according to an embodiment. 
         FIG. 12  is a block diagram illustrating an embodiment of an IHS. 
     
    
    
     DETAILED DESCRIPTION 
     For purposes of this disclosure, an IHS includes any instrumentality or aggregate of instrumentalities operable to compute, classify, process, transmit, receive, retrieve, originate, switch, store, display, manifest, detect, record, reproduce, handle, or utilize any form of information, intelligence, or data for business, scientific, control, or other purposes. For example, an IHS may be a personal computer, a network storage device, or any other suitable device and may vary in size, shape, performance, functionality, and price. The IHS may include random access memory (RAM), one or more processing resources such as a central processing unit (CPU) or hardware or software control logic, ROM, and/or other types of nonvolatile memory. Additional components of the IHS may include one or more disk drives, one or more network ports for communicating with external devices as well as various input and output (I/O) devices, such as a keyboard, a mouse, and a video display. The IHS may also include one or more buses operable to transmit communications between the various hardware components. 
       FIG. 1  is a block diagram of one typical IHS. The IHS  100  includes a processor  102  such as an Intel Pentium series processor or one of many other processors currently available. A memory I/O hub chipset  106  (comprising one or more integrated circuits) connects to processor  102  over a front-side bus  104 . Memory I/O hub  106  provides the processor  102  with access to a variety of resources. Main memory  108  connects to memory I/O hub  106  over a memory bus. A graphics processor  110  also connects to memory I/O hub  106 , allowing the graphics processor to communicate, e.g., with processor  102  and main memory  108 . Graphics processor  110 , in turn, provides display signals to a display device  112 . 
     Other resources can also be coupled to the system through memory I/O hub  106 , including an optical drive  114  or other removable-media drive, one or more hard disk drives  116 , one or more network interfaces  118 , one or more USB (Universal Serial Bus) ports  120 , and a super I/O controller  122  to provide access to user input devices  124 , etc. 
     Not all IHSs include each of the components shown in  FIG. 1 , and other components not shown may exist. Furthermore, some components shown as separate may exist in an integrated package or be integrated in a common integrated circuit with other components. As can be appreciated, many systems are expandable, and include or can include a variety of components, including redundant or parallel resources. 
     One physical configuration for an IHS  100  is as a “portable” or “laptop” computer. Such portable computers typically combine the processing components of IHS  100  with a display, input devices, and a battery in a common case, to provide a device that can be easily transported and used almost anywhere. As such, portable IHSs generally benefit from miniaturization of size and weight of the IHS components. Referring to  FIG. 2 , an exemplary view of a portable computer IHS  100  is illustrated in a typical clamshell configuration. In this clamshell configuration, a bottom shell  128  and a top shell  129  are hinged together with sufficient friction such that the top shell can be positioned at a variety of angles with respect to the bottom shell. The top shell can also be closed and latched to the bottom shell for easy carrying and protection of the display. 
     The top shell  129  houses display  112  and the bottom shell  128  typically houses the remaining components of portable IHS  100 . Most, if not all, of the user controls are typically mounted on or in the top surface  126  of bottom shell  128 . These controls can include a keyboard  130 , a touchpad  140  and touchpad buttons  141 ,  142 , a point stick  150  and point stick buttons  151 ,  152 , a power button  160 , and ancillary and/or media buttons  170 . The battery, electronics (including a motherboard to which the electronics are mounted or connected), and drive bays are located below the user controls within the bottom shell  128 , and as such are not apparent in  FIG. 2 . 
       FIG. 3  contains an exploded view of some of the components of a portable IHS.  FIG. 3  depicts the physical layout of the typical connections between the user input devices of a portable IHS and the motherboard. A motherboard  200  has connectors  133 ,  145 , and  155 , to connect the motherboard respectively to keyboard  130 , touchpad  140 , and point stick  150 . The keyboard requires a large (greater than 25 conductors) ribbon cable  131 , the cable having an end connector  132  to mate with connector  133  on motherboard  200 . Ribbon cable  131  transfers signals from the keyboard matrix to the motherboard and ultimately to the super I/O controller ( FIG. 1 ) for keystroke decoding. Additionally, a keyboard having a point stick  150  uses a smaller ribbon cable  153  having an end connector  154  to mate with connector  155  on motherboard  200 . Ribbon cable  153  transfers signals from the point stick  150  to the motherboard. The touchpad  140  typically is combined with touchpad buttons  141 ,  142  in a common touchpad module, which uses another ribbon cable  143  having an end connector  144  to mate with connector  145 . Ribbon cable  143  transfers signals from the touchpad module to the motherboard  200  and ultimately to the super I/O controller. 
     Other user inputs may also connect to the touchpad module. A point stick usually is accompanied by point stick buttons  151 ,  152 , which are located below the spacebar of the keyboard and above the touchpad module on the palmrest. A ribbon cable  156  connects the point stick buttons to the touchpad module. Also, ancillary/media button assembly  170  may connect by a ribbon cable  171  to the touchpad module. 
       FIG. 4  contains an electrical diagram  400  showing the electrical connections corresponding to the physical arrangement of  FIG. 3 . A keyboard matrix  330  on keyboard  130  couples through connector  133  to a set of matrix traces  312  on motherboard  200 . The matrix traces  312  connect in turn to an I/O controller  310 , which detects keystrokes and decodes them for processing by the IHS. The point stick  150 , also on keyboard  130 , couples through connector  155  to a set of point stick signal transfer traces  314  on motherboard  200 . The point stick traces  314  couple in turn to connector  145 . 
     Two other sets of traces couple connector  145  to I/O controller  310 . Touchpad controller traces  316  transfer signals that originate at a touchpad controller  350  to I/O controller  310 . Ancillary button traces  318  transfer signals that originate at ancillary/media button assembly  170  to I/O controller  310 . 
     A touchpad module  340  connects to motherboard  200  through ribbon cable  143  and connector  145 . A connector  344  on touchpad module  340  terminates the ribbon cable conductors to three sets of traces on a touchpad module  340 . A set of ancillary button signal transfer traces  348  routes signals from connector  344  to another connector  346 , which couples in turn to ancillary button ribbon cable  171 . A set of point stick traces  358  routes point stick signals to touchpad controller  350  for decoding. Finally, a set of touchpad controller traces  360  route signals from touchpad controller  350  to connector  344 . 
     Touchpad module  340  also contains the touchpad matrix  140  and touchpad buttons  141 ,  142 . A set of touchpad matrix traces  352  couple signals from matrix  140  to touchpad controller  350  for decoding. A set of touchpad button traces  354  couple signals from touchpad buttons  141 ,  142  to touchpad controller  350 . 
     Touchpad module  340  also contains a third connector  342  to connect to ribbon cable  156  and point stick buttons  151 ,  152 . A set of point stick button traces  356  on touchpad module  340  couple signals from the point stick buttons to touchpad controller  350 . 
     A number of deficiencies in this traditional user control interface design have now been recognized. First, the keyboard requires a relatively large interconnect to the motherboard, for what are each extremely low-frequency signal lines. Due to the central placement of the keyboard in the portable IHS, the keyboard connector  133  and large number of keyboard matrix traces  312  (see  FIG. 3 ) typically occupy extremely valuable real estate on the central portion of the motherboard, and complicate circuit board trace routing. The keyboard matrix also uses a large number of general purpose input output (GPIO) ports on the I/O controller, which could be used for advanced diagnostics and other purposes were they available. 
     Second, different laptop chassis designs and sizes—and even regional variations of the same design—usually require a unique keyboard due to different motherboard keyboard connector locations. It would be advantageous to decouple keyboard design from motherboard design to allow reuse of keyboards and keyboard components across multiple chassis and regions. 
     Third, current ribbon cable keyboard designs require a difficult “blind” assembly of the large connector. The keyboard is loosely placed over its final position in the case while the connector is mated with the motherboard, such that the keyboard itself obscures and interferes with the connection process. The process is unduly difficult for assemblers, and can result in damaged or improperly made connections. Users who remove their own keyboards may either not make the connection properly, or not even realize they have to make the connection, resulting in unnecessary service calls and returns. The multiple other palmrest connections (point stick, point stick buttons, touchpad) also slow assembly and are subject to damage or misalignment. 
     In systems with a point stick, connecting the point stick to the motherboard through one wire harness and then to the touchpad module through a separate harness from the motherboard is undesirable as it is complex, subject to damage, and can result in reduced signal integrity. 
     These and other problems are addressed by features found in one or more of the following embodiments. Generally, a keyboard controller is incorporated into the palmrest assembly (e.g., as part of the touchpad module) of a portable IHS. Various connections that are now required to the motherboard are made instead to the palmrest assembly. For instance, a new connector design allows a tab on the keyboard to be inserted into a socket in the palmrest assembly as part of mating the keyboard to the chassis, greatly simplifying assembly by, in essence, “docking” the keyboard to the system. The keyboard controller in the palmrest assembly can terminate many key press signals that were previously passed to the motherboard, and can communicate the content of the key press data with the motherboard I/O controller over a serial data bus requiring only a few traces. Other features and advantages of the embodiments will become apparent in the following description. 
       FIG. 5  shows the electrical connections of a first portable IHS embodiment  500 . Four assemblies are shown: a motherboard  502 ; a palmrest assembly  530 ; a keyboard assembly  580 ; and an ancillary button assembly  600 . Each will be described in turn. 
     Motherboard  502  includes an I/O controller  510  and other processing components (processor, etc., not shown) for the portable IHS  500 . The motherboard  502  also includes a connector  504 . Loopback traces  506  and  508 , keyboard controller bus traces  512 , and touchpad controller bus traces  514  connect the I/O controller  510  to connector  504 . 
     A ribbon cable or other wiring harness  520  couples connector  504  to a corresponding connector  532  on palmrest assembly  530 . Harness  520  includes loopback wires  522  and  524 , having electrical continuity respectively with loopback traces  506  and  508 , keyboard controller bus wires  526 , having electrical continuity respectively with the keyboard controller bus traces  512 , and touchpad controller bus wires  528 , having electrical continuity respectively with the touchpad controller bus traces  514 . The wiring harness also may include power connections (not shown) to power the components on the palmrest assembly. 
     Palmrest assembly  530  includes the motherboard connector  532 , a touchpad controller  540 , a touchpad matrix  542 , touchpad buttons  546 , a keyboard controller  550 , a keyboard connector  552 , an ancillary button connector  570 , and various circuit board traces to connect these components. These traces will be described in detail after introduction of the keyboard assembly components. 
     Keyboard assembly  580  includes an integral connector  582 , a point stick  586 , a keyboard matrix  590 , point stick buttons  592 , and various circuit board traces. 
     Some of the connections to the touchpad controller are similar to those of  FIG. 4 . Touchpad controller  540  is coupled to connector  532  by a set of touchpad controller bus traces  538 . A set of touchpad matrix traces  544  couple signals from matrix  542  to touchpad controller  540  for decoding. A set of touchpad button traces  548  couple signals from touchpad buttons  546  to touchpad controller  540 . 
     Instead of coupling through the motherboard, the point stick  586  in  FIG. 5  couples directly from the keyboard assembly  580  to the palmrest assembly  530 . Point stick signal traces  588  on keyboard assembly  580  couple through connectors  582 ,  552  to a corresponding set of point stick signal traces  558  on palmrest assembly  530 . Touchpad controller  540  couples to traces  558  to sense and decode point stick movements. This arrangement avoids the cumbersome point stick connection arrangement of  FIG. 4 . Should the keyboard assembly not include a point stick, traces  588  may be left unconnected, or removed from the assembly, with the corresponding connector leads in connector  582  left unused. 
     The arrangement of point stick buttons  592  also differs from  FIG. 4 . On keyboard assembly  580 , point stick buttons  592  are implemented on keyboard assembly  580 . Dedicated point stick button lines, shown in this embodiment as bundled with the keyboard matrix row and column lines  594 ,  596 , serve the point stick buttons  592 . In an embodiment, one or more keyboard matrix row or column lines could be shared between the point stick buttons and keyboard rows or columns. In one embodiment, the matrix lines serving the point stick button locations exist whether the keyboard assembly includes point stick buttons or not. The physical buttons are, however, not part of the assembly in some configurations, with the underlying point stick button locations covered and left inactive. 
     The keyboard matrix  590 , including portions of the matrix serving point stick buttons  592 , is coupled via keyboard matrix row lines  594  and keyboard matrix column lines  596 , through connector  582  and connector  552 , to palmrest keyboard matrix row traces  560  and palmrest keyboard matrix column traces  564 . Keyboard matrix column traces  564  join with ancillary button column traces  574  to form a combined set of column traces  562 , which couple to keyboard controller  550  (i.e., ancillary buttons  600  share some or all of their column traces with keyboard columns). Keyboard matrix row traces  560 , as well as ancillary button row trace(s)  572 , also couple to keyboard controller  550 . Keyboard controller  550  decodes keystrokes and ancillary button presses using signals received via traces  560 ,  562 , and  572 . 
     Ancillary button row traces  572  and column traces  574  couple to ancillary button assembly  600  via a connector  570  on palmrest assembly  530 , a wiring harness/cable  598 , and a connector  602  on ancillary button assembly  600 . Note that different ancillary button assemblies could be used with different button assignments, with appropriate firmware, and/or palmrest module  530  may be used without an ancillary button assembly. The ancillary button assembly (as well as keyboard assembly  580 ) may also include Light Emitting Diodes (LEDs) that are activated, e.g., from keyboard controller  550  outputs to indicate various functions or provide illumination of buttons, etc. 
     One feature shown in  FIG. 5  is a loopback diagnostic capability. The loopback diagnostic capability uses one or more of I/O controller  510 , touchpad controller  540 , and keyboard controller  550  to test the integrity of the connections between the motherboard and the palmrest assembly, the palmrest assembly and the keyboard assembly, and the palmrest assembly and the ancillary button assembly. This feature uses, e.g., freed GPIOs on I/O controller  510  and/or free GPIOs on controller  540  and/or controller  550 , in conjunction with loopback connections through the connectors. For instance, the previously described loopback traces  506 ,  508  couple through wires  522 ,  524  of harness  520  to palmrest assembly  530 . On the circuit board of palmrest assembly  530 , the connector  532  connections to wires  522 ,  524  are shorted together by a trace  534 . This allows I/O controller  510  to sense and diagnose a lack of connection between motherboard  502  and palmrest assembly  530 . In one embodiment, the loopback connections are spaced near opposite ends of connectors  504  and  532 , such that a connector that is partially inserted at an angle, with connections made at one end but not the other, can be detected. The I/O controller  510  notifies processing elements of the IHS when the palmrest assembly is not properly connected. 
     In  FIG. 5 , keyboard controller  550  manages similar loopback detection circuits for the connections to keyboard assembly  580  and ancillary button assembly  600 . For keyboard assembly  580 , a GPIO of keyboard controller  550  is coupled to two loopback traces  554  and  556 . Loopback traces  554  and  556  couple through connectors  552  and  582  to the keyboard assembly, where a trace  584  shorts the loopback traces together when the keyboard is connected properly. When the keyboard controller fails to sense a short, it notifies I/O controller  510  of a keyboard disconnect error. 
     In a similar manner, another GPIO of keyboard controller  550  is coupled to two loopback traces  566  and  568 . Loopback traces  566 ,  568  couple through connector  570 , harness  598 , and connector  602  to the ancillary button assembly, where a trace  604  shorts the loopback traces together when the ancillary button assembly is connected properly. When the keyboard controller fails to sense a short, it notifies I/O controller  510  of an ancillary button disconnect error. 
       FIG. 6  contains an exploded view of some of the components of a portable IHS according to an embodiment such as the  FIG. 5  embodiment.  FIG. 5  depicts the physical layout of the connections between the user input devices of the portable IHS and a motherboard  610 . Palmrest assembly  530  and keyboard assembly  580  connect or “dock” directly to each other, making electrical connections in the process for all keyboard and point stick functions. Ancillary button assembly  600  connects to palmrest assembly  530  via ribbon cable/wiring harness  598 . Palmrest assembly  530  connects to motherboard  610  via ribbon cable/wiring harness  520 , which has a connector  612  that mates with connector  504  on motherboard  610 . Generally, ribbon cable/wiring harness  520  contains only a small number of wires as compared to the three motherboard cables of the  FIG. 3  configuration. This allows connector  504  to be smaller, more flexible in positioning, and capable of positioning nearer the periphery of the motherboard. The keyboard can also be removed without disturbing any connections to the motherboard. 
       FIG. 7  depicts an exemplary embodiment  700  of electrical connections to a palmrest assembly  740 . These connections are made at a keyboard connecting tab  710 , an ancillary connector  720 , and a motherboard connector  730 . At the keyboard connecting tab  710 , connections exist for a keyboard loopback function, point stick termination, point stick buttons, key columns, and key rows (e.g., auxiliary keys, function keys, number keys, “QWERTY” keys, “ASDFG” keys, “ZXCVB” keys, and space bar row keys). At the ancillary connector, connections exists for an ancillary loopback function, a key column subset, and a media/ancillary button row. At the motherboard connector, connections exist for a palmrest loopback function, power, touchpad I/O, and keyboard I/O. Some functions may require more connections than are shown, depending on implementation. Other functions, such as status LEDs, may also be supported through the connections. 
     In one embodiment, the connection between a palmrest assembly and a keyboard assembly is made using a rigid connection tab that is fabricated directly into the keyboard assembly. Such a structure is shown in  FIG. 8 , which depicts a lower central portion of a keyboard assembly  580 , with the keys removed. The keyboard assembly contains a lower support  830 , e.g., made of a rigid material such as stamped aluminum sheet. During fabrication of lower support  830 , a connection tab  800  with insertion guides  802 ,  804  is formed. 
     A keyboard matrix layer  832  overlies lower support  830 . The keyboard matrix layer includes row and column traces and appropriate insulating layers. The row and column traces, as well as other traces such as those to point stick  586 , route to edge contacts  840  on connection tab  800 . A rubber sheet, including rubber domes  810 ,  812 ,  814 ,  816 ,  818 ,  820 ,  822 ,  824 , and  826 , overlies the keyboard matrix layer  832 . Each rubber dome is placed at the location of a key (not shown) that will exist in the final assembly. A carbon center underlies each rubber dome, such that when an overlying key is depressed, a plunger on the key pushes down on the dome, causing the carbon center to complete a connection with a corresponding row line and column line. 
     In some embodiments, the same basic assignment of edge connectors  840  is used for point stick and non-point stick versions of the keyboard assembly. Rubber domes  810  and  812  may be non-existent in the non-point stick version, or domes  810  and  812  may be made nonfunctional, e.g., by covering them with a solid member and/or by removing their carbon center. 
       FIG. 9  shows a bottom view of keyboard assembly  580  and a palmrest assembly  530 , illustrating an assembly sequence. An expanded bottom view of one section  900  of palmrest assembly  530  is also illustrated. Section  900  includes a floating docking port  920  to receive keyboard connection tab  800  and its insertion guides  802  and  804 . Floating docking port  920  includes a set of contacts  910  to make with edge contacts  840  ( FIG. 8 ) of keyboard assembly  580  when keyboard connection tab  800  is fully inserted. Floating docking port  920  preferably flexes upwards (down in  FIG. 9 ) to allow the keyboard connection tab  800  to be tilted downwards slightly for insertion. Floating docking port  920  preferably also allows slight transverse shifts to accommodate alignment of the keyboard assembly with the IHS chassis. To accommodate these features, contacts  910  can connect to the circuit board of palmrest assembly  530  via a flexible flat cable or the like. 
     One other feature shown in  FIG. 9  is a T-shaped slot  860  in the rigid lower member of keyboard assembly  580 . Slot  860  facilitates assembly, and will be explained further below with respect to  FIGS. 11   a - 11   c.    
       FIG. 10  shows further details of the assembly of a portable IHS  950  according to an embodiment. In  FIG. 10 , palmrest assembly  530  has been previously assembled to a lower clamshell chassis  955  of portable IHS  950 . The upper surface of chassis  955  contains an opening  960  to receive keyboard assembly  580 . Opening  960  includes a depressed lip  962  to support keyboard assembly  580  in the final assembly. 
     Keyboard assembly  580  is assembled to portable IHS  950  by first engaging keyboard connection tab  800  with the floating docking port on the bottom side of palmrest assembly (see  FIG. 9 ) and sliding the keyboard assembly towards the palmrest assembly. Keyboard assembly  580  includes locator tabs  970 ,  972 ,  974  to engage respectively with three locator slots  964 ,  966 , and  968  in the lower edge of depressed lip  962 , as the keyboard assembly nears its final alignment. Fastener tabs  976 ,  978 ,  980 , located along the top edge of keyboard assembly  580 , can then receive fasteners to secure the keyboard assembly to the portable IHS. 
       FIGS. 11   a - 11   c  show an additional keyboard retention feature useful in embodiments.  FIGS. 11   a - 11   c  show a magnified view of one section of chassis  955  and one section of keyboard assembly  580  during the final assembly process. Keyboard detail is omitted such that the T-shaped slot  860  in the rigid lower member of keyboard assembly  580  is visible. Fastener tabs  980  and  978  are also visible, with their respective fastener holes  982  and  984 . 
     The magnified section of chassis  955  includes additional details for the depressed lip  962  of opening  960 . Lip  962  includes fastener mounting holes  986 ,  988 , which will align with fastener holes  982  and  984  in the final assembly. Lip  962  also includes a mushroom connector  990  protruding from its bottom surface. 
     In  FIG. 11   b , keyboard connection tab  800  has been engaged sufficiently with the floating docking port on the bottom side of the palmrest assembly (see  FIGS. 9 and 10 ) to allow the keyboard assembly  580  to lie flat against lip  962 . Before the keyboard assembly can lie flat, mushroom connector  990  must align with the wider section of T-shaped slot  860 , such that the mushroom connector can protrude through the slot. In this position, tabs  800 ,  970 ,  972 , and  974  are not yet fully engaged, and fastener holes  982  and  984  are not yet aligned with fastener mounting holes  986 ,  988 . 
     In  FIG. 11   c , the keyboard assembly has been fully engaged by sliding it towards the lower edge of lip  962 . In the fully engaged position, mushroom connector  990  is retained in the narrower portion of T-slot  860 . The mushroom prevents lifting of the upper edge of keyboard assembly  580  with the assembly in final alignment. In this alignment, fasteners can now be inserted into fastener holes  982  and  984  and secured to fastener mounting holes  986 ,  988 . 
       FIG. 12  illustrates a block diagram for a portable IHS  1000  including features described above. Processor  102 , frontside bus  104 , memory I/O hub  106 , main memory  108 , graphics processor  110 , display device  112 , optical drive  114 , hard disk drive  116 , network interfaces  118 , and USB ports  120  function in similar fashion to their counterparts in  FIG. 1 . A super I/O controller  1010  communicates upstream with memory I/O hub  106 , and communicates downstream with a touchpad controller  1020  and a keyboard controller  1030 . The connections to controllers  1020  and  1030  are made across a palmrest interface  1014 . A palmrest loopback circuit  1012  is also coupled across palmrest interface  1014 , and connects to super I/O controller  1010 . 
     Touchpad controller  1020  communicates with a touchpad  1022 , and communicates with a point stick  1024  across a keyboard interface  1026 . 
     Keyboard controller  1030  communicates with a keyboard  1032  across the keyboard interface. A keyboard loopback circuit  1036  is also coupled across keyboard interface  1026 , and connects to keyboard controller  1030 . Keyboard controller  1030  also communicates with ancillary buttons  1034  across an ancillary interface  1038 . An ancillary loopback circuit  1040  is also coupled across the ancillary interface  1038 , and connects to keyboard controller  1030 . 
     Various features of the embodiments above can be combined in a variety of ways, or implemented using other mechanical and/or electrical constructs. Embodiments can be implemented with a variety of user selection controls. A keyboard assembly that will never support a point stick or point stick buttons need not have edge contacts and matrix traces for point stick controls. Likewise, a palmrest assembly need not have a touchpad and related electronics, and could have other selection controls such as a track ball. Other connections, such as a power button connection, could route directly from the keyboard through the palmrest assembly to the motherboard. Key switches other than rubber dome switches can be used to translate user keystrokes and button presses into electrical signals. 
     In some embodiments, keyboard commonality across platforms is aided by dimensionally referencing the keyboard “center” (intersection of “G”, “B”, and “H” keys) to the touchpad. Various chassis can then be provided to accept the same basic keyboard layout. 
     Although illustrative embodiments have been shown and described, a wide range of other modification, change and substitution is contemplated in the foregoing disclosure. Also, in some instances, some features of the embodiments may be employed without a corresponding use of other features. Accordingly, it is appropriate that the appended claims be constructed broadly and in manner consistent with the scope of the embodiments disclosed herein.