[sdiy] EPROM conversion question

[ASSI]

On Mittwoch, 22. März 2006 03:28, klosmon wrote:
> for the rev 2 version 7.0 -- for some reason, this version will NOT
> work when copied into a 2716.

This sounds like somehow this particular firmware is accessing locations 
outside the normal memory map and is expecting to see something 
specific, which would depend on the details of the address decoding, 
chip enable and perhaps what a non-enabled (hi-Z) EPROM output reads as 
in that particular circuit - this could be all ones, all zeros, random 
or the last data on the bus before all outputs were going hi-Z. The 
last one resulted in one of the hardest to find bugs I've witnessed and 
luckily I've seen this only once. The things that are easily verified 
is putting a copy of the low half into the upper half and putting all 
zeros or all ones there. If that doesn't work, then you'll probably 
have to jig up the enable input so that the EPROM is unselected for its 
upper half.


Achim.
-- 
+<[Q+ Matrix-12 WAVE#46 Neuron microQkb Andromeda XTk sonic heaven]>+

SD adaptations for KORG EX-800 and Poly-800MkII V0.9:
http://Stromeko.Synth.net/Downloads.html#KorgSDada