Emulating Tetris Gameboy version on the Amstrad CPC 6128

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ivarf
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Emulating Tetris Gameboy version on the Amstrad CPC 6128

Post by ivarf » Tue Oct 06, 2020 7:23 pm

Image


Link to a Youtube-video showing it running on real hardware
https://www.youtube.com/watch?v=fFqsJg7 ... e=emb_logo

Note, this is the Amstrad 6128 plus version, not the Amstrad CPC 6128 version.
Last edited by ivarf on Wed Oct 07, 2020 9:33 am, edited 1 time in total.

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gunbladelad
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Re: Emulating Tetris Gameboy version on the Amstrad CPC 6128

Post by gunbladelad » Mon Oct 12, 2020 7:04 am

I used to think back in my teenage years that the Gameboy and CPC should be able to play similar games as they both used the same processor - and now someone's managed it...
Where logic won't work, I will

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ivarf
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Re: Emulating Tetris Gameboy version on the Amstrad CPC 6128

Post by ivarf » Tue Oct 13, 2020 3:27 pm

gunbladelad wrote:
Mon Oct 12, 2020 7:04 am
I used to think back in my teenage years that the Gameboy and CPC should be able to play similar games as they both used the same processor - and now someone's managed it...
Very impressive to emulate it so well. Very close to perfect, except for the music. They still work on it trying to improve the sound. Too bad the Amstrad CPC had no quality synth like the C64s SID. Do anyone know if the synth in the Yamaha MSX is on better or worse than the SID?

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Re: Emulating Tetris Gameboy version on the Amstrad CPC 6128

Post by Matt_B » Tue Oct 13, 2020 5:08 pm

The GameBoy actually has quite a decent sound system for what's generally seen as a quite primitive piece of hardware. You've got four channels: Two pulse wave (basically square wave of arbitrary width), white noise and DPCM for sample playback.

The AY chip in the CPC has only three channels, can't only do square waves and noise, and sample playback hogs the CPU. The Plus could potentially do better using the audio co-processor, but I don't think it'd be an easy task.

The SID chip can do pulse waves, but that's about it. None of its other features would be particularly relevant.

The YM2151 in the CX5M was a superb sound chip with 8-channel 4-operator FM synthesis, also seen in some professional keyboards at the time such as the DX-21. However, while that's great for music, it's not much use for emulating a GameBoy.

Actually, the best chip in an 8-bit machine for the job would be the one in the NES, in that it does everything but with the addition of triangle waves. You'd just have a job trying to emulate a Z80 at playable speed with its CPU.

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ivarf
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Re: Emulating Tetris Gameboy version on the Amstrad CPC 6128

Post by ivarf » Tue Oct 13, 2020 7:48 pm

Wait a minute. Is the soundchip in the Yamaha CX5M MSX really a development of the legendary Yamaha DX7?

https://gist.github.com/bryc/e85315f758 ... 4fdeef01c5
"DX7: YM2128(0) (OPS, FM Operator Type-S) and YM2129(0) (EGS)
mid 1983, the original FM synthesizer, direct predecessor to YM2151/YM2612 etc."

370 Arcade games that used this chip (including Outrun):
https://vgmrips.net/packs/chip/ym2151

Yamaha DX7 - The Synthesizer that Defined the '80s
https://www.youtube.com/watch?v=Q1Ha0MMT0aA

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Re: Emulating Tetris Gameboy version on the Amstrad CPC 6128

Post by Matt_B » Wed Oct 14, 2020 12:52 am

Yes, the YM2151 was basically a cost-reduced DX-7 integrated onto a single chip. A further development was the YM3812 used in the AdLib and Soundblaster PC cards, although the world of popular music had largely moved on to sample-based synths like the D-50 and M1 by then so they're not held in quite such high regard.

The CX5M was a bit ahead of its time though. The MSX1 was just underpowered for the job, the software wasn't great, and the rudimentary MIDI implementation made it pretty much useless as a sequencer or controller. The Atari ST pretty much killed it, by virtue of having full MIDI, better software and a much more powerful computer.

Anyway, getting back the the GameBoy emulation, I suspect that we probably won't see a whole slew of games because it's relying upon much of the GameBoy hardware not being used and the CPU being idle for a lot of the time during which the graphics hardware can be emulated. Anything that uses the sprites and scrolling is probably right out. Still, maybe Dr Mario might be possible?

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Re: Emulating Tetris Gameboy version on the Amstrad CPC 6128

Post by TheAlex » Thu Oct 22, 2020 3:38 pm

Matt_B wrote:
Tue Oct 13, 2020 5:08 pm
The GameBoy actually has quite a decent sound system for what's generally seen as a quite primitive piece of hardware. You've got four channels: Two pulse wave (basically square wave of arbitrary width), white noise and DPCM for sample playback.
Definitely! As proven in various live music performances, sometimes pretty much Gameboys only:

Chipzel:
https://www.youtube.com/watch?v=lpYoRm_InaY

Trey Frey and four Gameboys:
https://www.youtube.com/watch?v=cFz43VTRyE4&t=250s

I'd like to give it a go myself one day (though I don't have a Gameboy - maybe I should buy one and have no idea what prices are like): https://www.littlesounddj.com/lsd/index.php

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