Extend the Ceda/Sanco computer with a soundcard.
The soundcard is connected to the Z80 bus, exposed via the "EXBUS" connector on the Ceda's mainboard. The heart of the sound generation is the SN76489AN from Texas Instruments, a three voice (+1 for noise) programmable sound generator. In this project one can find the hardware schematic and protoboard design, a music player for CP/M able to read VGM music files, and an Arduino sketch that can be used to check the functionality of the 76489 chip.
soundcard: the circuit used for this project. The PCB was never realized, it's just a guideline for the protoboard placement and wiring;vgmplay: the music player. It can read .VGM files from the disk;arduino-76489: a proof-of-concept used to test the SN76489 chip before starting with the project.
| Part No | Part ID/value | Description |
|---|---|---|
| U1 | SN76489AN | Programmable sound generator (*) |
| U2 | 74LS138 | 3-to-8 decoder |
| C1 | 100n | Ceramic/poly decopuling capacitor |
| J1 | 25x2 | IDC connector (same as SCSI) |
| J2 | - | Audio jack or screw terminal (audio out) |
(*) The usage of variants of this chip may require adjustments, i.e. the slower clock variant may require a separate clock.
The application can be assembled with assembler included in z88dk toolchain. Open a terminal and launch
cd vgmplay
make