[sdiy] Alesis Midiverb eprom images

Robin Whittle rw at firstpr.com.au
Mon Nov 1 09:50:28 CET 2010


Hi Tony,

Here are the raw binary images of the EPROM which drives the DSP
section, for the MIDIVerb in its two incarnations - a reverb device
and an effects device (delay etc. if I recall correctly):

  http://www.firstpr.com.au/temp/MIDIVERB/MVERBREV
  http://www.firstpr.com.au/temp/MIDIVERB/MVERBFEX

I took these and used them in the mid-80s, but haven't used them
since.  It is possible to make a dual mode device, with a toggleswitch
to select between two EPROMs, or to control the highest address bit of
a 27C512.

I think the MIDIVerb DSP section is remarkable - just an EPROM,
standard logic chips, RAM and a DAC, with a bit of analogue circuitry.
 It performs A to D, stereo D to A and then all the effects.  I recall
staring at the circuit for a long time and still not being able to
figure out how it works.

  Cheers

    - Robin         http://www.firstpr.com.au/rwi/dfish/

> Hi list,
> 
> I think I messed up the 27C256, U51, eprom when I read it in my trusty old eprom programmer.
> I discovered that to my horror it wasn't properly seated in it's ISA slot.
> I looked at the bins and could see only a partial read was succesful, i.e. lower 512 are all FF's.
> Now the unit behaves erratically and distorts and overloads.
> I also read the 2764 operating system, and it also partially read.
> I took the normal static precautions and used a ground strap.
> 
> I am devastated and am pleading with anybody who might have a copy of the images they'd be willing to share.
> I can trade for some other machines eprom images.
> 
> This is the original 12 bit DAC/SAR Midiverb.
> 
> U51 27C256 label reads "MVOBJ 2-6-86" ( effects programs)
> U54 2764 label reads "MVOP 4-7-86" (operating system for the 80C31)
> 
> Appreciate any help with this, in the meantime I have contacted Alesis in a last ditch effort.
> 
> Tony Kalomiris



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