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1-Bit Forum Compo 2015

category: general [glöplog]
For the record, PC speaker can be bit-banged by the cpu just like speccy, which is how we pulled off the multichannel player at Revision. 8253 use is not mandatory (it can only produce squarewaves anyway). And whatever 3-channel trick used in obscure computers can't be used on PC as only one output is tied to the speaker pin.

I've never heard of the PC beeper being considered "hardware accelerated" before.
added on the 2015-07-29 07:13:07 by trixter trixter
Yes, it can be bit-banged, just like nearly everything else. Yes, it is not mandratory, but it is there, while most of other systems (ZX Spectrum, Apple II, TI8x calcs, and so on) we use to make 1-bit sounds don't have this kind of hardware. So we can't ignore this fact while attempting to define what '1-bit music' is and what isn't. 8253 counter isn't much different from a PSG (SID, AY) internal counters, including ability to generate sound while CPU doing other things, so it is kind of close to the borderline. We consider it 'true' 1-bit music anyway, because it is true 0/1s, true retro platform, and so on.
added on the 2015-07-29 07:45:32 by Shiru Shiru
@utz: thanks. tried beepola and it was easy but slow to edit due to quite poor interface (copy only works thru drop down menu, page down/up doesn't move in 16 or 32 so that it would be helpful in pattern editing). but sound is nice and it works(main).

pattern command to change the sound engine on the fly would result in interesting mayhem(not 1 -bit anymore..but maybe it could be programmed so that it would be?!)..
added on the 2015-07-30 14:27:35 by 1in10 1in10
@utz: had idea for compo track. did the track in beepola. beepola crashed. no compo track.

will check these programs again after they are out of beta stage and native on osx.
added on the 2015-08-02 20:57:20 by 1in10 1in10
@trixter: 15 years or so ago I used PC speaker extensively as FastTracker sound output and it sounded quite well.

Basically if you clock any 1-bit output fast and smart enough, you can play whatever you wish. Or just grab any CD player with 1-bit delta-sigma DAC and play anything. ;)
added on the 2015-08-03 11:27:05 by KK KK
@KK: You must have had a really loud speaker.

Sigma-Delta Modulation is not really possible on 4.77MHz PC because you'd need extremely high output rates that the 8088 can't provide. Pulse-Width modulation (the standard 6-bit-ish PC speaker DAC trick) is a special-case form of SDM that operates at 1.193182 MHz (the timer rate) by using PIT channel 2 in one-shot mode. SDM would sound better but there's just no way to bitbang the speaker at nearly 1.2 MHz when the CPU itself is running at 4.77 MHz ;-)

ZX Spectrum engines have been ported to PC without any timer use at all; Saboteur and Fantasy World Dizzy come to mind.
added on the 2015-08-04 05:38:00 by trixter trixter
One week left till the deadline ;)
added on the 2015-08-25 11:21:54 by utz utz
Uh, now I know what I forgot
added on the 2015-08-25 14:11:05 by Triace Triace
Deadline has been extended till September 13th :)
added on the 2015-09-01 13:27:47 by utz utz
yaayyyy. utz, you are so awesome
added on the 2015-09-02 18:36:44 by Czery Czery
what do we win again?
added on the 2015-09-08 02:23:55 by FunGas FunGas
trixter: I know 4.77MHz PC won't do sigma-delta. Wha I meant is that some (most?) CD players will fit into 1-bit category nicely.
added on the 2015-09-08 11:13:57 by KK KK
I'm expecting some baller MONOTONE tunage!
added on the 2015-09-08 15:15:58 by Scali Scali


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