Circuitbenders Forum

Circuitbenders Forum => Drum machines => Circuitbending discussion => Roland & Boss => Topic started by: lazydog on March 11, 2012, 09:56:40 PM

Title: 626/505 sound eeprom. can this be done?
Post by: lazydog on March 11, 2012, 09:56:40 PM

TR-707 Battery-powered with quick-swappable EPROM sounds (http://www.youtube.com/watch?v=p8vgDzgI02E#)

(zif socket sound eeproms for 707, as described on tr707 usergroup)

apparently, all the details are described on the usergroup. do the 707
and 626/505 have a lot in common?
(probably easier to midi it up to a sampler ;) )

Title: Re: 626/505 sound eeprom. can this be done?
Post by: Gordonjcp on March 11, 2012, 10:26:08 PM

I wrote some code to unscramble the TR626 ROM, but I've no idea where it is now.  I do know that it's 8-bit linear and the pins are swapped about to make it easier to route the board.

The two big ASICs in the TR626 are very fragile, and mine died.  This is why I stopped hacking on it.

(Edit: here's a link to an mp3 of the 626 demo with my modded ROM, maybe I'll find the ROM itself later - http://www.gjcp.net/~gordonjcp/drums.mp3 (http://www.gjcp.net/~gordonjcp/drums.mp3))

Title: Re: 626/505 sound eeprom. can this be done?
Post by: lazydog on April 01, 2012, 01:30:58 PM

 ;)
in other words, best to use it to drive a sampler or other, eh.
a lot easier and quicker.

do you think it would be possible to have a switch to disable playing
the onboard preset patterns? (other topic, i know, but i don't want
to start a new one). they are pretty bad, and hazardous, if you were
to consider using it in a live context.

in case you've forgotten its operation, 3 buttons select 6 banks of patterns,
each toggling a preset/user bank. not hard to avoid the A,B,C banks(preset),
you just have to press twice, but if you get it wrong, it could be embarassing.
a toggle switch disabling A,B,C selection would be #cool#.

the other thing that would be nice is a backlit display: those light-strips, could
they be used here?

(oh, while i'm offtopic...): what about more +5v triggers? would that be possible?
(eg: from each drum)...just thought it could become a neat sequencer for some
gate triggered modules... (...)(...) ... saw some mention of this from a 505, but
what would the power issues be, and would it interfere with audio etc.?
could also be a switchable thing.

Title: Re: 626/505 sound eeprom. can this be done?
Post by: Gordonjcp on April 01, 2012, 11:14:34 PM

No, they're built into the firmware ROM which is most likely mask-programmed into one of those big fragile custom chips.