System Components

Processors (CPUs, Processor Adapters, CPU Upgrade Modules...)
Memory (error handling, presence detect)
Storage (Floppy, Hard Drive, CD-ROM, Tape...)
Video
Sound
Model "M" Keyboard

Ports and Peripherals
   Keyboard Port
   Mouse Port
      Optical Wireless Mouse
   Parallel Port (Modes, ExpressPrint)
   Serial Port
   Wrap plugs (For diagnostics)
   PC-2-PC Cables (Serial and parallel LapLink cables)
   Joystick Metrics

RTC - Real Time Clock
   PS/2 CMOS Batteries (by Bob Eager and Peter Wendt)
   Reworking Dallas RTC Modules (thanks to Peter Wendt)
   MC146818 (Clearing the RTC, HW vs SW clock)

IBM ROM Images (by Jim Shorney)
Flash Memory (late PS/2s only)
IBM PS/2 ASICs List of IBM VLSI Application-Specific ICs