Alternate and Multichanel PC speaker sounds

[kool kitty89]

A while back I noticed that a few, early PC games used more than jsut single channel square wve for PC, while simultaneously using the square wave. It sounds rather quiet and like a saw or pulse wave to me. I seem to recall the Apple II using doing somthing like that as well.

The 2 exaples I know of are Stormlord and Digger. (albeit sotormlord doesn't use it in-game -possibly as there was no in-game music in-game anyway -if they were basing it on the Amiga port at least -just ambit sound plus SFX)

http://www.youtube.com/watch?v=jR8vuBgjnlA


http://www.youtube.com/watch?v=7kz0_KWIMEU

[Rusty Venture]

Blasphemy for not knowing this!

[kool kitty89]

I do know that, that was part of what I was referring to with the Apple II comment, but my main focus was the PC. Anyway, looking at wiki's discription, the Apple II audipo was done by careful CPU regulated control of the simple clickign noise it produced. I seem to recall that similar manipulation can be done with the Atari 8-bit's keyclick sound as well. (generated by CTIA/GTIA)

I don't know of the PC having an equivelent to that though, perhaps some other kind of software driven sound. The thing is, Digger is a very early PC game and seems to make decent use of the effect, whatever it is, so if if is CPU driven, it can't be too intenssive. SO why wan't it used more? (stormlord even has 2 channels using that sound)

[TmEE]

its called PWM and it is very CPU intensive, depending on how clean sound you want...

[kool kitty89]

Note: I'm not talking about sample playback, I already know that's PWM, and very CPU intensive, and probably what the Apple II is using for that sample for ghostbusters, but I was talking about the simple music in the other 2 examples. I know this is PWM, for example: http://www.defacto2.net/includes/blo...epcspeaker.mp3


Unless that's PWM too, which would ampunt to simple pulse waves (non square) being used for music, but mixed in software or what? (it would seem pretty intensive for Digger, given it was intended for a 4.77 MHz 8088 machine to be used in-game alogn with software driven graphics)