Re: Emulating a SID (or sort of)... with a 65xx.

From: Jim Brain <brain_at_jbrain.com>
Date: Fri, 28 Aug 2020 21:31:03 -0500
Message-ID: <e252cfd6-8cc2-4972-658e-223a1ada7a82_at_jbrain.com>
On 8/28/2020 8:36 PM, tokafondo wrote:
> Everybody building a SBC that wants sound output gets to the same wall: There
> are not sound generators, or programmable sound generators, or such kind of
> chips available like they were 30 years ago. Yes, you can get them a pulled
> ones, or old stock, or you can go the FPGA, PIC or Arduino route and get one
> of those sound cores that end being more powerful than the SBC itself, just
> to get SID or FM sound.
>
> There has been discussions about getting funcion generator chips, couple
> them to an external amplifier chip, and use them to generate waveforms based
> basic sounds.
>
> And I even read recently as having a 6502 CPU in a SBC just to generate
> sound.
>
> So... How difficult could be to get a 65xx CPU, have it generate a waveform
> with its ADSR settings, process it applying filters or whatever, and
> bitbanging it to a DAC, to generate sound?
>
> In another words: how feasible would be to implement a sort of SID (or
> whatever other generic PSG chip) engine in a 65xx chip, that could be used
> inside the same cpu, or act as an external sound chip for a main CPU? Do
> exist such a thing?
>
>
>
> --
> Sent from: http://cbm-hackers.2304266.n4.nabble.com/
>
The 6809 on the Color COmputer does this all the time, since that 
machine has no sound chip.  So, all sounds for that machine are done via 
the CPU (I think the TS1000 does this with the Z80, and the early IBM 
did it with the 8088 as well). So, it's definitely doable (not sure 
about ADSR, but square wave and maybe triangle wave might be possible).

But, that's exactly what SwinSID and ARMSID do, but they use much faster 
CPUs (16 + MHz).

Jim


-- 
Jim Brain
brain_at_jbrain.com
www.jbrain.com
Received on 2020-08-29 05:00:03

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