[sdiy] Alesis Midiverb eprom images

[m.bareille at free.fr]

Hello,

I did this 'mod' many times and all my Midiverb/fex are tweaked like this :)

MidiVerb and Midifex share  the same hardware exactly, the difference is only
into the 'object' eprom who contain effects algorithms ( or IR models may be ? )
The reverb structure look like a  discrete TTL/CMOS logic DSP , with a 12 bits
DAC.

You can put Midiverb and Midifex datas all into a 27C512 eprom, add a switch on
the panel  to swap the MSB adress of the eprom to selec 'verb'or 'fex' area and
then you get a two in one effect box with 127 preset instead of 63 :)

It is very easy to do , it work really fine :)

Just take  care to use a fast eprom with 70nsec latency . I you use a 100nsec or
slower  eprom it make very ugly noise ( digital bugs ) because the eprom cannot
provide datas fast enough

Cheers,

Marc B.

Papareil Synth Labs
http://m.bareille.free.fr





Selon Tony Kalomiris <ic1 at bell.net>:

> Morning Robin and list memebers,
>
> Ok I re-read your message, and think I understand now.
> The MIDIVERB and MIDIFEX units only use one half of the 27C256 eprom.
> That's why I got one half unprogammed for the first 16 K (not 256 as
> originally reported) - all FF's.
> Ok the programs start at $4000.
> The MVERBREV image is from the MIDIVERB and the MVERBFEX is from the MIDFEX
> unit, I'm guessing.
> So  I would need to load these into a 27C256 and toggle the high order
> address bit, not a 27C512.
> Sound about right ?
>
> Tony Kalomiris
>
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at dropmix.xs4all.nl
> http://dropmix.xs4all.nl/mailman/listinfo/synth-diy
>