Coming from the Commodore 64 and being used to coding in assembler, I tried to do the same on my dad’s 386 PC. I decided on a DYCP effect, a popular effect in the Commodore 64 demoscene.
The DYCP itself (the bouncy scroller) wasn’t too hard; most effort and fun went into the music routine for the Soundblaster’s OPL2 (Yamaha YM3812) chip. This is the chip on the Soundblaster that was has a little FM synthesizer in it.
Getting sound out of it involved sending the right number to the various registers of the chip (for pitch, ADSR, operators and modulator and such). This was all in assembler; “composing” the music involved creating different table of numbers to be sent in sequence to the chip, using the music routines I knew from my Commodore 64 heroes as inspiration.