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

From: Gerrit Heitsch <*gerrit_at_laosinh.s.bawue.de*> Date: Sat, 29 Aug 2020 15:45:35 +0200 Message-ID: <02021c24-ce5b-1d6e-7b54-fea97e9880aa_at_laosinh.s.bawue.de> · gerrit_at_laosinh.s.bawue.de

On 8/29/20 3:02 PM, smf wrote:
> On 29/08/2020 02:36, tokafondo wrote:
> 
>> 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?
> 
> 6502 wouldn't be my first choice. You've got no on chip timers, so every
> path would need to be programmed in constant time.
> 
> Add a 6522 for timing and you might as well just use that for generating
> the sound, you can specify the rate and it will generate a square wave.

That's why I suggested a 6532, you get I/O, a timer plus 128 Bytes of 
RAM that way. The 6522 has the advantage of being able to use the shift 
register as a sound generator that needs less CPU intervention than pure 
bit banging, but it has no RAM.

  Gerrit