reading from parallel port Sound Digitizers

selco · 02 June 2020, 22:26

There where several digitizers for the parallel port for the Amiga.
How would one read the samples from these digitizers?

I guess we need a CIA timer-interrupt got read at the correct interval to get the selected sample rate, right?

Does anybody have a piece of code ready to demonstrate this job?

How did stereo digitizers word? Is ther a protocol description avaulable somewhere?

Best regads

Hm, now I found a tiny piece of asm code in
https://archive.org/stream/1990-span...amiga_djvu.txt page 181
and in the German version of that book "Das Musikbuch", S. 299

But how is that code timed? Is this just a busy wait loop that works correctly on an 7MHz 68000 only???

hooverphonique · 03 June 2020, 10:37

Quote:

Originally Posted by selco

But how is that code timed? Is this just a busy wait loop that works correctly on an 7MHz 68000 only???

Yes.. It looks like the value in D0 (when entering "record") is used as a busy-wait loop count.

Toni Wilen · 03 June 2020, 10:48

Usual method is to read byte from sampler, convert it to word (copy low 8-bits to upper 8-bits), write it to AUDxDAT, then poll for audio interrupt (or use interrupts normally but it gets really tight if 68000..), clear interrupt request, repeat.

AUDxPER selects sampling (and playback) rate.

selco · 03 June 2020, 11:20

I see... Thanks for the info!
Does that mean each sample is played back?

Toni Wilen · 03 June 2020, 12:33

Yes, sampled audio playback is included for free when using this method

02 June 2020, 22:26	#1
selco Registered User Join Date: Aug 2013 Location: Germany Posts: 81	reading from parallel port Sound Digitizers There where several digitizers for the parallel port for the Amiga. How would one read the samples from these digitizers? I guess we need a CIA timer-interrupt got read at the correct interval to get the selected sample rate, right? Does anybody have a piece of code ready to demonstrate this job? How did stereo digitizers word? Is ther a protocol description avaulable somewhere? Best regads Hm, now I found a tiny piece of asm code in https://archive.org/stream/1990-span...amiga_djvu.txt page 181 and in the German version of that book "Das Musikbuch", S. 299 But how is that code timed? Is this just a busy wait loop that works correctly on an 7MHz 68000 only??? Last edited by selco; 02 June 2020 at 23:06.

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03 June 2020, 10:48	#3
Toni Wilen WinUAE developer Join Date: Aug 2001 Location: Hämeenlinna/Finland Age: 49 Posts: 26,505	Usual method is to read byte from sampler, convert it to word (copy low 8-bits to upper 8-bits), write it to AUDxDAT, then poll for audio interrupt (or use interrupts normally but it gets really tight if 68000..), clear interrupt request, repeat. AUDxPER selects sampling (and playback) rate.

03 June 2020, 11:20	#4
selco Registered User Join Date: Aug 2013 Location: Germany Posts: 81	I see... Thanks for the info! Does that mean each sample is played back?

03 June 2020, 12:33	#5
Toni Wilen WinUAE developer Join Date: Aug 2001 Location: Hämeenlinna/Finland Age: 49 Posts: 26,505	Yes, sampled audio playback is included for free when using this method

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