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Hey guys!

I'm new here, but I'm working on a music interface for the 8-bit sega consoles. I have genesis/master system cartridges developed, as well as a game gear cart. At this point in the project, I just need help with the rom itself. It's based on a rom developed by little-scale called SMSM. I have added a screen that displays some text to let you know it's loaded (before it would just stay at the SEGA screen). My z80 skills are basically nonexistent though, so I thought I'd reach out to see if anyone is interested in helping out.

I'm willing to compensate you for your time. We can work the details out, but it could be money, or hardware, or something. I'm pretty open.

Basically what I want is to replicate a similar rom for the gameboy called mGB. It won't let me post an image of it, but if you google "mgb gameboy" you can find a screenshot of the rom.

The SMSM interface plugs into controller port 2, so I'd like controller 1 to be able to configure various options of the sound chip: pulse width, vibrato, etc. I am not an expert on the 8 bit sega sound chip, so input on features would help a lot.

Most of the logic for configuring the sound chip is implemented, but it's only configurable with midi cc commands.

I'm not sure how intensive a project like this would be, so if you have any thoughts please post or PM me!

Thanks!

SMSM is doing all the heavy lifting in the microcontroller, the software running in the system is just relaying commands to the PSG chip. This is a ridiculously simple chip with virtually no state or sound adjustment capabilities, it relies on the software to constantly adjust it. For example, to do vibrato the software must adjust the frequency (or rather, wavelength) control register many times per second. All volume envelopes are done in software. So it's unable to make any of the adjustments you mention without a bunch of extra code (a sound engine) and a change to the protocol to interface with it on a higher level. This is quite possible, just a bit more than you suggest.

Author	Message
catskull Joined: 01 Aug 2016 Posts: 1 Location: USA	[PAID] Help develop homebrew music rom Posted: Mon Aug 01, 2016 4:39 pm
catskull Joined: 01 Aug 2016 Posts: 1 Location: USA	Hey guys! I'm new here, but I'm working on a music interface for the 8-bit sega consoles. I have genesis/master system cartridges developed, as well as a game gear cart. At this point in the project, I just need help with the rom itself. It's based on a rom developed by little-scale called SMSM. I have added a screen that displays some text to let you know it's loaded (before it would just stay at the SEGA screen). My z80 skills are basically nonexistent though, so I thought I'd reach out to see if anyone is interested in helping out. I'm willing to compensate you for your time. We can work the details out, but it could be money, or hardware, or something. I'm pretty open. Basically what I want is to replicate a similar rom for the gameboy called mGB. It won't let me post an image of it, but if you google "mgb gameboy" you can find a screenshot of the rom. The SMSM interface plugs into controller port 2, so I'd like controller 1 to be able to configure various options of the sound chip: pulse width, vibrato, etc. I am not an expert on the 8 bit sega sound chip, so input on features would help a lot. Most of the logic for configuring the sound chip is implemented, but it's only configurable with midi cc commands. I'm not sure how intensive a project like this would be, so if you have any thoughts please post or PM me! Thanks!

Maxim Site Admin Joined: 19 Oct 1999 Posts: 14762 Location: London	Posted: Mon Aug 01, 2016 9:14 pm
	SMSM is doing all the heavy lifting in the microcontroller, the software running in the system is just relaying commands to the PSG chip. This is a ridiculously simple chip with virtually no state or sound adjustment capabilities, it relies on the software to constantly adjust it. For example, to do vibrato the software must adjust the frequency (or rather, wavelength) control register many times per second. All volume envelopes are done in software. So it's unable to make any of the adjustments you mention without a bunch of extra code (a sound engine) and a change to the protocol to interface with it on a higher level. This is quite possible, just a bit more than you suggest.

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