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

[Mattias Rickardsson]

At 11:05 2005-01-21, Colin f wrote:
>
> > 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 key scanning routine, which runs every 1.8ms, reads the step key state
>and pattern data in groups of 4, updates the pattern memory and outputs the
>current data to the LED drivers. The 808 service manual goes into quite a
>lot of detail about how this works.
>The data is read from memory as it is strobed to the LEDs.
>CPUs of the 808 kind will probably only have 2 or 3 internal registers, so
>there'd be no space to cache a pattern.

Thanks Colin, this is great info. I haven't read the 808 manual thoroughly 
enough for some years, so I wasn't sure about these details.


/mr