Dual AY 3-8910/3- 8912 chip sound cartriridge for ATARI 8bit
Melody psg :
- 2 x AY 3-8910 or 3-8912 chips
- software selectable output frequences:
- 1.77 MHz for zx spectrum music files
- 1 Mhz for Amstrad, Oric music files
- 2 MHz for Aatari st music files
- The Atari ST soundchip has a 2mhz frequency, while most 8bit machines (including the Oric) have a 1mhz soundchip. This means that in order to replay correctly an Atari ST music from Oric we have to double the value of the frequency registers else the music will play too low which will result in ugly waveforms and low notes.
- The Oric computers are equiped with a AY-3-8912 sound chip
- This component can be found in multiple variants in many other systems such as the MSX, Amstrad CPC, Atari ST, some of the Sinclair Spectrum machines, among other
- The YM file format was originally designed by Arnaud Carré as a way to record Atari ST musics to make them replayable on a PC.
- Technically a YM file is simply a register dump of the music: A program captured 50 times per second the content of the values sent to the YM chip. With 14 registers to record, 50 times per second, it means that one second of music takes 700 bytes, so roughly 42kbytes per minute of music.
- The MYM files are basically YM files that have been uncompressed and recompressed in a way that allows for partial decompression over time. The efficiency is not as good, but at least it works.
in development :-); soon more details