IBM PC Compatible Computer Project – Specifications

The original IBM PC Model 5150 I used had the following specifications:

Original IBM PC

  • 8088 Processor @ 4.77MHz
  • 256KB RAM
  • CGA Video Card
  • Speaker/Beeper
  • Dual 5.25″ 160KB Floppy Drives
  • COM / LPT Expansion Card
  • Model F Keyboard

I think that was pretty much it. I believe it was running DOS 3.3 and we has applications such as Word Perfect, Lotus 123 and some typing tutor program.

Our Homebrew Version

My goal is to recreate the general experience of using an IBM PC, however there are some concessions I am going to make for right now. Below is a list of what I am aiming for:

  • 8088 Processor @ 4.77MHz.
  • 512KB RAM
  • CGA monochrome graphics.
  • Speaker/Beeper
  • Floppy Emulation
  • LPT Port
  • PS/2 Keyboard Interface

The reasoning for the specs above mostly comes down to simplifying the design while keeping it useful. Implementing only 512KB of RAM allows easier decoding of the control logic and requires only one memory chip. Displaying monochrome video removes a lot of complexity from the video circuit. Since floppy drives are not as common or inexpensive as they used to be, using a SD card or USB or something to simulate a floppy is a preferable choice. I would like an LPT port to connect this to an old printer I have to make it feel useful. And, a PS/2 interface for the keyboard because PS/2 keyboards are still plentiful and I may have a few laying around.