[sdiy] Alesis MidiVerb II DSP

[Margus Kliimask]

Hi,

Thanks. By now I have gone through most of the board, and your description
sounds pretty similar to what I have here.   

All Alesis custom chips of that era seem to be 68 pin PLCCs. 
PCM54 is a (pretty common) 16-bit DAC, same as in MVII. 
CXK58256 is a 32K SRAM (mine has 4 4416 DRAMs totalling the same 32K, but
organized as 16x16K as the DSP itself is 16 bit). CY7C128 is a SRAM serving
as a common data area for parameters and programs (algorithms) that are not
internal to DSP. 
80C31 seems to have been Alesis favorite for control CPU in most of the
stuff of that era.
XICOR chip is a 2K EEPROM storing user patches among other things. MVII has
only a tiny 32 byte serial EEPROM for that as there are no user configurable
programs.

Thanks for your info.
Margus

-----Original Message-----
From: owner-synth-diy at dropmix.xs4all.nl
[mailto:owner-synth-diy at dropmix.xs4all.nl] On Behalf Of Andre Majorel
Sent: 15 December 2006 03:30
To: synth-diy at dropmix.xs4all.nl
Subject: Re: [sdiy] Alesis MidiVerb II DSP


On 2006-12-15 01:56 +0200, Margus Kliimask wrote:

> Does anyone have any idea what is the DSP (?) chip inside Alesis 
> MidiVerb II? It has Texas Instruments logo, and is marked as: 
> CF61252FN
> N    48816
> 8715 (probably time of manufacturing)
> 
> Any ideas? Datasheets would be even better :) And does anyone know 
> whether the same one is inside MidiVerb III ?

My Midiverb III has a Fujitsu JAPAN; MB653327U; 8932 E01; ALESIS 89Z in a
square 68-pin package (PLCC ?). It sports a big sticker saying "MFG1025".

Nearby chips :

  DIP28 BB JAPAN; PCM54HP; 8910 C7 040 (ADC or DAC)
  DIP28 Sony 9F07; CXK58256P-12L; JAPAN 751798 (prob delay SRAM)
  DIP24N CY7C128-45PC; USA8927; 35405

On the other side :

  DIP40 Signetics SC80C31BCCN40; 2295K06 8931KE (CPU)
  CERDIP28 with label "ALESIS 10-9-89 A; MV3 V1.00 A321" (CPU ROM)
  DIP24 XICOR; X2816BP; T8929 (CPU program RAM ?)

-- 
André Majorel <URL:http://www.teaser.fr/~amajorel/>
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