[sdiy] TB-303 cpu question

[Roy J. Tellason]

On Monday 14 November 2005 05:59 pm, Senso wrote:
> >Following on to my post re buying a cpu, I have a TR-606 cpu which
> >is the same as the 303 cpu apart from the mask rom, is there any way
> >I can modify it to work in the 303 (I'm half tempted to try it as is
> >to see what it does as is!) I wonder if it would be possible to get
> >the 606 cpu to address an external rom, I have no idea how or indeed
> >if it is possible, so any input welcomed!
>
> I don't remember in which instruments, but I know that in some Roland
> machines you can switch from external eprom to the internal masked
> rom by disconnecting one pin.
> One would expect the opposite to work as well.
>
> Senso

I don't remember what instrument it was either,  but in one repair I did a 
bunch of years back there was a "software upgrade" that involved replacing 
the original CPU which used an external eprom with another one that had 
masked rom in it.  The new part in there,  the unit was *dead*.  So I called 
'em,  and they'd forgotten to tell me about the other thing I needed to do, 
which was to move two "zero ohm resistors" that were functioning as jumper to 
the other set of pads nearby.

-- 
Member of the toughest, meanest, deadliest, most unrelenting -- and
ablest -- form of life in this section of space,  a critter that can
be killed but can't be tamed.  --Robert A. Heinlein, "The Puppet Masters"