Yes, Bawami can play on the PC speaker! Here, you can see my MIDI player doing a few things that my old Bleeper Music Maker never could (such as pitch-bends, and working on Windows 7!).
The wonderfully detailed MIDIs played here are made by SX. The songs are “Second Flight” (OP theme of Onegai☆Twins, TV ver) and “Eternal Blaze” (OP theme of Mahou Shoujo Lyrical Nanoha A’s, TV ver).
BaWaMI is a work-in-progress program of mine. It’s designed to play MIDI files (or live MIDI input) on the soundcard, with instruments being made from a filtered “Basic Waveform”. However! I decided to add support for using the PC speaker as much as possible. For Bleeper Music Maker, MIDI support was merely an addition, but Bawami was designed for MIDI from the start. This means it has a knowledge of pitch-bends, vibrato and instrument volume envelopes, which are all put to use when it controls the PC speaker.
Also, Bawami communicates with the PC speaker’s timer chip on the motherboard directly and can tell it to simply “start” making sound and worry later about when to stop it. BMM could only tell Windows to “beep” for a given duration, and since it couldn’t look into the future to see when it should stop, it had to repeat many short beeps, which sounded bad when only playing one note.