A Video Upgrade?

Why? Is the predominant first question. If you find that your computer does its job, but you would like to see it work a lot faster (in SLOW), if your tired of that annoying fast mode flicker, if you have a program longer than 16K of BASIC and want it to run without crashing, then this is for you. Have you put mucho time and money into your little computer? Do you not want to spend a lot more to get a bigger computer and start from scratch again? Please keep reading.

Among other advantages, this project gives you the following enhancements:

1. No FAST or SLOW screen flicker.
2. SLOW runs 5.5 times faster (almost as fast as FAST).
3. No display file crashes at all. Memory restrictions are removed for BASIC and machine code (with opt. mod to some memories).
4. COLOR on the screen and LOWER CASE letters on the screen and 2040 printer. This system can be made compatible with the Memotech I/F additional decoding required and others.
5. The video output is 75 ohm composite video.
6. No additional memory space is required (I/O mapped), and return to standard Sinclair video is as easy as unplugging the boards (some mods may change this).
7. The IX register is available for programming and memories using the Z80 refresh register will run ‘in spec’.
8. Almost all software will run as is, although some MC programs will run too fast (I love it!). Basic games become exciting to play.
9. This project is 8K ZX80 compatible if it is not previously upgraded.
10. The advanced capabilities of the TMS9918 are at your disposal if you want a challenge in machine code.

Remember, this is the same chip that the Adam, TI99, MTX512 (Memotech) and the new japanese MSX type use, for video display.

This project is a major undertaking and will be divided up into two installments plus additional information as we uncover it later. For those of you who are board builders, we have included exact size board layouts and finished pictures. JLOs’ prices are excellent however, for those of you who want to ‘kit’ it (finished photos in next issue).