Interfacing the F18A to the Apple II

What does it take to interface the F18A, a modern FPGA-based clone of the venerable TM9918A Video Display Processor (VDP), to an Apple II? Short answer: not much. Here’s the long answer.

Let’s start with analyzing the design of the E-Z Color Graphics Interface, a TMS9918A-based “sprite board” with the design published in the August 1982 issue of Byte. Examine the schematic in Figure 4.

There are six major sections of the circuit:

  1. The TMS9918A VDP
  2. The clock generation circuit
  3. Video memory
  4. Video output
  5. Bus interfacing
  6. Decoupling capacitors

The F18A includes the functions of sections 1 through 4. So, with only one F18A, a few capacitors, and a single 74LS00 (for the bus interface), we’ll have a working sprite board for the Apple II. Sounds like a job for SuperProto.