Comment by suprjami 10 hours ago
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...
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).
Must've been an Am386 or OC since the 33 MHz part was the fastest Intel 386DX.
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..
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.
Fascinating. It sounds awesome!
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
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.
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.