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

[Mattias Rickardsson]

At 23:19 2005-01-20, Colin f wrote:
> > > At 12:49 20/01/2005, Mattias Rickardsson wrote:
>
> > >> 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?
>
>The CPUs are very simple, I don't imagine they are doing any caching of
>current patterns.

D'oh... I just realized that the 16 LEDs show the pattern for the selected 
instrument immediately when the pattern starts, so of course the data must 
be cached to some extent... :-/

The question is, however, what happens around this mechanism. Maybe only a 
cached version of the data of the current pattern is used, maybe the 
caching is only for display purposes and not for trigging the actual 
sounds, or maybe it's somewhere in between.

Does anybody know? :-)

> > > What are you trying to do? If it's customised pattern
> > > sequencing/creation

Yes, it is indeed. :-)

>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.

I agree, it would be a very possible idea, but hopefully not necessary for 
a simple [but still powerful] concept.

>But if you change the microprocessor, and develop a more advanced UI, you
>lose the character of the instrument.

Yes, in that case I definitely wouldn't want to lose anything of the UI. 
Possibly make it a little bit more "easy to use" in some sense, but this 
also implies losing a bit of the UI...


/mr