Hello!
I always thought that this DECO machine was ahead of its time and it could do so much more.
As it has a 6502 like the apple and 2x AY-3-8910 I thought that it could play Spectrum PT2/PT3 tunes and also MSX and CPC tunes although those computers run on a Z80, but nothing I havent done before. Porting tunes from Apple II with a Mockingboard could have these capabilities too (https://en.wikipedia.org/wiki/Mockingboard). So I rolled up my sleeves and got hands on!
The result is some very nice extra items in the Deco menu that play tunes for those machines and take it to an absolute new level compared to the games it has.
Notice that DECO has only 4KB ram avalaible for audio CPU and more or less 25Kb available of data in main CPU, so in order to make it work, I have to compress the modules, unpack in real time as they are beeing transfered to the sound CPU and like if it was an amiga mod, I decompress in real time the pattern that will be played next, so we maximize and squeeze the memory to the maximum level. In other words, each tune is packed in chunks, and the main CPU depacks one chunk at a time in real time into a 3 KB double buffer while the audio CPU plays.
With only 0x6000 bytes of Ram, I have to split it like this:
$0000-$0502 1,283 zero page, stack, cassette BIOS while loading.
$0503-$53FF 19,709 the menu image (code + font + logo + packed tunes)
$5400-$5FFF 3,072 the depack double buffer
Stay tuned for new releases.....
I always thought that this DECO machine was ahead of its time and it could do so much more.
As it has a 6502 like the apple and 2x AY-3-8910 I thought that it could play Spectrum PT2/PT3 tunes and also MSX and CPC tunes although those computers run on a Z80, but nothing I havent done before. Porting tunes from Apple II with a Mockingboard could have these capabilities too (https://en.wikipedia.org/wiki/Mockingboard). So I rolled up my sleeves and got hands on!
The result is some very nice extra items in the Deco menu that play tunes for those machines and take it to an absolute new level compared to the games it has.
Notice that DECO has only 4KB ram avalaible for audio CPU and more or less 25Kb available of data in main CPU, so in order to make it work, I have to compress the modules, unpack in real time as they are beeing transfered to the sound CPU and like if it was an amiga mod, I decompress in real time the pattern that will be played next, so we maximize and squeeze the memory to the maximum level. In other words, each tune is packed in chunks, and the main CPU depacks one chunk at a time in real time into a 3 KB double buffer while the audio CPU plays.
With only 0x6000 bytes of Ram, I have to split it like this:
$0000-$0502 1,283 zero page, stack, cassette BIOS while loading.
$0503-$53FF 19,709 the menu image (code + font + logo + packed tunes)
$5400-$5FFF 3,072 the depack double buffer
Stay tuned for new releases.....
