TMS 9918A Video Upgrade ROM

Two board, extensive upgrade that integrates the TMS 9918A video display processor into the ZX81/TS1000. Provides: color multiple graphics resolutions, up to 256×192 pixels up to 32 sprites a SLOW mode almost as fast as FAST mode blink free FAST mode lower case characters instead of inverse upper case Interfaces the TMS 9918A color graphics

As can be expected with any major hardware upgrade, there are a few conflicts when the Oliger video system is used in conjunction with other equipment. Summarizes the fixes we and others have come up with to date.

The TMS9918A video project consists of two PC boards, a small modification/addition to the main computer board, and a +5, +12, -5 VDC power supply (an expansion board of some type is necessary). Video board “A” contains the TMS9918 VDP chip, 16K video ram and one support chip for I/O interfacing. Board “B” contains the

This second installment involves some explanation of the changes to the operating system and how they have been implemented. By actually placing the contents of the ROM on EPROM, you can change any routine, implement extra commands outside of the 8K ROM and have BASIC control of your new routines. It is only necessary to