Comment by suprjami - Hacker Neue

suprjami Dec 3, 2025 parent

One of my favourite DOS era inventions is Access Software's RealSound™ technology which performed audio modulation of the PC speaker to produce okay sounding audio playback, about telephone quality.

The manual hilariously instructs you to hook your hifi system up to the PC speaker, see the last page:

https://www.gamesdatabase.org/Media/SYSTEM/Microsoft_DOS//Ma...

nine_k Dec 3, 2025

Star Control II was released in 1992, a year before Doom, and it was able to play beautiful, rich 4-channel MOD music via PC speaker, on a 80386 @ 40Mhz.

Scream Tracker, a music composition software, was able to pull of the same feat, 4 channels of 8-bit voices, in 1990.

However cool and useful the PC speaker output was, it was the a hand-soldered "Covox" lookalike, a passive DAC built out of a resistor ladder and attached to the printer port, which you actually connected to your hi-fi amplifier.

krige Dec 3, 2025

Fast Tracker 2, admittedly "bit" later than 1990, could route playback of however many channels you used to the speaker.

Worth noting that the quality in these cases was pretty good. A bit staticky but still well above Wolfenstein 3D sound effects most people associate with PC Speaker (covox-less).

ErroneousBosh Dec 3, 2025

> However cool and useful the PC speaker output was, it was the a hand-soldered "Covox" lookalike, a passive DAC built out of a resistor ladder and attached to the printer port, which you actually connected to your hi-fi amplifier.

I must have built at least a couple of dozen of these for various people.

porjo Dec 3, 2025

Good times! I made one as a kid and remember thinking there is no way in heck this thing will work. My mind was blown when it worked first time.

suprjami OP Dec 3, 2025

No, RealSound was not a Covox-like hardware dongle. It was PC speaker only. Play the first few minutes of Mean Streets or Martian Memorandum or Countdown in DOSBox and you'll hear it.

nine_k Dec 3, 2025

I know. Experiencing that made me learn about PWM, and I was able to reproduce, harshly, a voice sample on my 2 MHz 8-bit home computer, by bit-banging the tape recorder port's 1-bit output.

vidarh Dec 3, 2025

You could play music on the C64 by sampling the tape ports 1bit input and twiddling the sound chips volume accordingly.

You could of course store the samples too, to play back later, but doing realtime sampling into 64KB of RAM didn't exactly let you store much... And a 1MHz CPU didn't let you do much compression if you wanted to keep up..

cluckindan Dec 3, 2025

You could in fact play four sample channels (with filters) plus two SID channels. However, the tech to do that was only discovered around 2008.

https://youtube.com/watch?v=ZMioAPZcays

https://youtube.com/watch?v=D2lEVw7fsMY

EvanAnderson Dec 3, 2025

I did this on an Apple IIe years before I had a sound card on my PC (or a sampler for my Amiga). It seemed so cool to me, even if I didn't exactly understand how it worked.

burnt-resistor Dec 3, 2025

Must've been an Am386 or OC since the 33 MHz part was the fastest Intel 386DX.

EvanAnderson Dec 3, 2025

An example of how RealSound sounded: https://youtu.be/havf3yw0qyw

Edit:

This sent me down a rabbit hole and I found this nice video about PC speaker history: https://youtu.be/jD4m9JvLy2Y

minikomi Dec 3, 2025

Fascinating. It sounds awesome!

https://www.youtube.com/watch?v=havf3yw0qyw

tass Dec 3, 2025

I’ve had this music in my head for 30+ years. I could never get very far in the game though!

bananaboy Dec 3, 2025

"Can't be too happy about that one!" I always loved the speech in World Class Leader Board Golf!

Suppafly Dec 3, 2025

I don't remember which software I used, I don't specifically recall it being realsound, but I had a soundblaster emulator driver that used the pc speaker that wasn't half bad. Got me through hours of Kings Quest and Space Quest. I also used a driver that made the computer think my monochrome monitor had CGA capabilities.

consp Dec 3, 2025

Wasn't the last one mainly to use Hercules cards in cga only applications?

Suppafly Dec 5, 2025

Probably, I mostly used it to play games on hardware that they generally didn't want to run on.

moepstar Dec 3, 2025

I recall having "Pinball Dreams" also similar (same?) tech - the soundtrack through the speaker was quite good!

djmips Dec 3, 2025

Except those #$!@# patented it. We were doing the same thing before them even going back to the Apple II. I described it to my father and he said it was an obvious technique.

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