Music player for CoCo and Dragon computers targetting the SN76489 in the Game Master Cartridge.
Work in progress. Plays two tone channels plus a noise channel with frequency controlled by the third tone channel for percussion.
Derived from CyD (Copyright 2013-2015 Ciaran Anscomb)
Modified for the SN76489 by Stewart Orchard 2018
Needs: asm6809, bin2cas.pl, dzip, perl
git clone https://github.com/sorchard001/cyd-gmc
cd cyd-gmc
make
xroar -cart gmc -no-cart-autorun cyd_gmc.bin
Timing is derived from the video refresh rate, meaning the playback tempo will be different for PAL and NTSC machines. The demo tune is arranged for a PAL machine. Increase the note length in music.s from 6 to 7 to slow down the playback speed for NTSC:
; basic note length
n1 equ 6 ; PAL
n1 equ 7 ; NTSC
Game Master Cartridge design by John Linville:
http://www.vintageisthenewold.com/game-master-cartridge-enables-better-games-for-coco/
SN76489 information: