A new standard of almost perfection has been achieved, thanks to my perusal of the XT Technical Reference Manual.
The last model of the IBM PC/XT supports 640KB of RAM on the motherboard without any alteration (not that the earlier XT boards require any serious modification to support 640KB.) This eliminates the need for a conventional memory expansion card. With the IBM PC Expansion Unit, a full 16 ISA slots are available to the machine, if only 14 are useable.
05/09/86 BIOS
IBM PC Math Coprocessor (8087-5)
IBM Expansion Unit Extender Card .
IBM Color/Graphics Display Adapter + IBM Color Display (5153)
IBM Diskette Drive Adapter + 2 x IBM 5.25" 320/360KB Diskette Drive + 1 x IBM 3.5" 720KB Extenal Diskette Drive
Hercules Graphics Adapter + IBM Monochrome Display (5151) +
IBM CPS Matrix Printer (5152)
IBM Game Control Adapter + 2 x IBM PCjr. Joystick (custom adapter)
IBM Printer Adapter + IBM Color Graphics Printer (5182)
IBM Music Feature Card + Midi Adapter Unit
IBM Asychronous Communications Adapter + Microsoft Serial Mouse
In the main unit, we have almost everything from IBM. I have tried to keep all essential devices within the main unit. One slot is used to connect to the Expansion Unit. The Asych card is connected to slot 8 because that slot is very finicky about the cards it accepts. The Diskette Adapter can support two internal disk drives and two external disk drives, but IBM only allowed for one external disk drive. The disk drives are full-height models. Ideally, the midi adapter unit should come with the Music Feature Card. Finally, because IBM never made joysticks for the PC, I have decided to use PCjr. joysticks with a simple pin converter/adapter.
IBM Expansion Unit Receiver Card
IBM Fixed Disk Adapter (Xebec 1210) + 2 x 10MB IBM Fixed Disk Drives
Roland MIF-IPC + Roland MPU-401 Midi Processing Unit + Roland MT-32 Multi-Timbre Sound Module
Adlib Music Synthesizer Card
Creative Music System Card (a.k.a. Creative Game Blaster)
Covox Sound Master + 2 x digital pads
Creative Sound Blaster .5
IBM Asychronous Communications Adapter + Hayes Smartmodem
IBM Model M Keyboard (1391401).
In this part of the case, we have two 10MB full height drives. The Fixed Disk Adapter can support two of these drives. The Roland interface card is a simple device and the MPU-401 is a big box with the controller circuitry and the MT-32 is attached to it. The Hayes Smartmodem is of the external variety, and varieties exist in 300, 1200 and 2400 baud.
The Covox should take care of any Speech Thing games as well as early Covox titles. The Sound Blaster .5 is my term for a Sound Blaster with the CMS and Adlib chips removed.