Topic: How to detect SID if is present?

[MIRKOSOFT]

Hi!

I know how to detect SID chip type.

It works also when is SID not present but type is not true (out of motherboard or other).

Can explain me anybody how to check if is SID present?

Many many thanks for every help, reply or comments.

Miro

[Hydrophilic]

You sure ask some strange questions!  I mean, it seams if you can determine the type of chip (6581/8580) then simple detection should be simple... Anyway, here is what I would do
 

Code: [Select]

sid = $d700 ;example SID base address
LDA #<sid
LDX #>sid
STA $FE ;any old zero-page address for pointer
STX $FF
LDA #0 ;reset value
LDY #7*2 ;start of voice 3 (frequency registers)
STA ($FE),Y ; voice 3 freq. low
INY
STA ($FE),Y ; voice 3 freq. high
INY
STA ($FE),Y ; voice 3 pulse-width low
INY
STA ($FE),Y; voice 3 pulse-width high
INY
LDA #$41 ;gate voice, pulse waveform
STA ($FE),Y ; gate voice 3
 
LDY #$1B ;voice 3 oscillator read-only register
LDA #$FF ;inversion of $00
CMP ($FE),Y
BNE no_sid
 
LDY #7*2+3 ;voice 3 pulse-width high
STA ($FE),Y ;set to $FF
LDY #$1B ;voice 3 oscillator read-only register
LDA ($FE),Y ;test inversion of $FF (test $00)
BNE no_sid
 
;SID present!

I have tried this in VICE with and without stereo SID.  I also tested against VICE with normal SID and my real C128.  All that works okay, but I do not have a real stereo SID to test.
 
I hope that helps!
 
Edit
I attached the test program.  From MONITOR enter J1300.  If SID is present, nothing happens.  If SID is missing, then border will flash and you have to press STOP.

[MIRKOSOFT]

Hi Robert!

Thank you very much for source & program.... works correctly...

Miro