msxnet > Konami MSX Games > Synthesizer
Konami's Synthesizer, RC 741, is not a game but a program to make music with. The cartridge has a D/A converter on board. The original cartridge came with a tape with samples on it (not as sound, it has to be loaded by Synthesizer).
The cartridge has an 8bit D/A. It's unsigned and unbuffered and accessed through memory-mapped I/O address 4000h; I don't know if only that address is hardwired to the D/A -- but the software only uses that address.
As far as I know, MESS is the only emulator that emulates this D/A. The rom image is available at ftp.funet.fi.
Saku Taipale owns the original cartridge. He sent me .wav files of the tape, which I then converted to .cas format. The original .wav files were over 80MB, but the converted .cas files are just 87Kb.
The .cas files are actually just samples, played at different sample-rates. So you can play the .cas on your computer. Of course they're not in .wav format, but here are the .cas and converted files:
Saku Taipale has scanned the covers of the original package. They're available at ftp.funet.fi.