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Emulated modifications: VRAM expansion (64Kb), disconnect "wait" MSX2 cpu #117

@degegede123

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@degegede123

The MSX2 allows for two easy and significant hardware modifications.

  1. Literally stacking memory chips to expand VRAM.
  2. Disconnecting the wait function (pin) that slows down the CPU, for compatibility with MSX1.

I would like to experiment with these features in MSXpen. MSX2 unhinged.
I have not tried such modifications. Articles about the exact implementation can be found on the web.

A 10% faster CPU (4Mhz) and 64Kb more VRAM is an interesting situation.

At face value my request is more of the same of what is available:

  • the possibility to adjust the speed (*1.1)
  • more plain VRAM (total: 192Kb)

Documentation is sparse. The VRAM upgrade might be more complicated, which limits use cases.
Only one 192Kb MSX2 was produced in Japan for subtitling. I can find no serious exploration of the options.

A third change to MSXpen might be stereo. Some machines had a switch on the back to split the PCM sound channels (3) to left, center, right (or another combi). Worth it? I think it's an interesting option. Depending on the applied sound chip, schematics for mods can be found.

Overshadowed by the emerging 16 bit machines, I thought as a kid: the thing still has quirky potential. Forty years after release I would like to add a nice contribution, maxing out on that latent potency. What if?

I hope that we share an enthusiasm to make shine what was just under the surface.

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