[sdiy] x0x memories (TB-303, TR-606, TR-808)

[Richard Wentk]

At 12:49 20/01/2005, Mattias Rickardsson wrote:
>Hi,
>
>I have some things that I must delve deeper into, and maybe you can help me.
>
>The TB-303, TR-606, and TR-808 have a microprocessor (containing also the 
>program code, I believe) and some memory ICs beside it (holding the 
>pattern/song data, I believe).
>
>Is this external memory used in such a way that it could be "emulated" by 
>some other thing connected to the same microprocessor pins?
>
>What I mean is basically this:
>Does the 808 read the external memory ICs continously (like a sheet of 
>music notes) while playing, so that an emulator could decide at any time 
>what the next step should contain? Or is the external memory read in 
>larger chunks, stored in the microprocessor while playing, and nothing can 
>change it while playing?

I'm pretty sure the drum machines are step based. But the 303's glide 
feature would need some lookahead.

>(Has anybody done some neat tricks or analyses with this x0x memory 
>architecture?)

What are you trying to do? If it's customised pattern sequencing/creation, 
it might be easier to go the other way round - throw out the microprocessor 
and the memory completely, and replace it with trigger circuitry of your 
own design, keeping the audio circuitry intact.

Richard