Posted By
siz
on 2021-09-08
02:41:52
|  Re: Sidekick264 - software defined cartridge
@Frenetic:
> Does the SID model detection play a role on 264s?
I do detect SID type in my programs with the following routine but AFAIK no one does anything differently based on the SID type on our platform. (And most of the SID cards use 8580 anyway)
detsidtp:
// Set a low freq. for Osc.
// (Voice 3) #$0200 which is
// somewhere between B-0 and
// C-1, according to demo
ldy #15
lda #$02
sta (sidptr),y
// Set Sawtooth and Triangle
// waveforms for voice 3 and
// start release of ADSR
ldy #18
lda #%00110000
sta (sidptr),y
// Check if output of voice 3
// ever goes higher than $80.
// It's only possible on new
// SID chip (8580) and never
// on the old one (6581)
ldy #0
ldx #0
sty ystore
loop2: ldy #27
lda (sidptr),y
bmi newsid
dex
bne loop2
ldy ystore
dey
sty ystore
bne loop2
beq oldsid
newsid: lda #%10
ora io_soundtype
sta io_soundtype
oldsid: rts
(I know that I copied this one from somewhere but I don't remember the source.)
As for FM emulation: it doesn't matter if it's 2 or 3 addresses. I'm fine with both of them. We can keep 3 to follow Commodore's legacy.
(And yes, I plan to expand my SizPlay to support some well known FM file formats)
|
