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Old 02 June 2020, 22:26   #1
selco
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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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Old 03 June 2020, 10:37   #2
hooverphonique
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Quote:
Originally Posted by selco View Post
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.
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Old 03 June 2020, 10:48   #3
Toni Wilen
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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.
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Old 03 June 2020, 11:20   #4
selco
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I see... Thanks for the info!
Does that mean each sample is played back?
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Old 03 June 2020, 12:33   #5
Toni Wilen
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Yes, sampled audio playback is included for free when using this method
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