Hi,
I bought a Victor HC-30, supposedly an MSX1 with a V9938 VDP and 16KB VRAM, with the intent do use it as MSX1 with an 80 columns text-mode.
I tried with the Yamaha CX5M-II subROM, with no success. Then, I adapted the CT80E ROM, which works like a charm in openMSX, but gave only broke screens in real machine.
Motivated by Leonard Oliveira and Tabajara, I was convinced that something (like MODE1 pin) was unconnected in the VDP. So, I openned the machine and began to follow the circuit lines, only to find that the SDIP-64 VDP installed in this MSX had a completely incompatible pinout with the V9938 or V9958.
So, I removed the metallic shield and saw that the VDP isn't (as supposed before) an V9938, but an YM2220. The only reference about this IC was about Yamaha AX-150, but there people guessed that YM2220 was V9938 related, probably because it uses the same package.
For what I know now, the pinout is very similar to the 315-5066, used by Sega in SG-1000 II. Maybe it's a derivative with only the VDP enabled? Also I already know that the 80 columns text mode is unavailable.
And now I am writing this post. Did you know which tests can be done to identify this VDP capabilities or differences between it and other compatible implementations?
Thanks!
Piter Punk
