[sdiy] SRAM Memory Upgrade (Old Sampler) ???

[Plutoniq9]

Actually, the SRAM is backed up by (5) normal AA batteries that can power 
the sampler as well. In the absence of power to the VCC of the newer 4Mb 
RAM, the internal lithium battery kicks in. This is a benefit of the ram 
upgrade, never have to worry about losing samples again.

I'm excited :)

Ryan


>From: Ingo Debus <debus at cityweb.de>
>To: diy synth <synth-diy at dropmix.xs4all.nl>
>Subject: Re: [sdiy] SRAM Memory Upgrade (Old Sampler) ???
>Date: Sun, 28 Aug 2005 17:39:07 +0200
>
>
>Am 27.08.2005 um 21:30 schrieb ::Phuture:::
>
>>Right now, the sampler uses a single 32k x 8-bit 28-pin DIP CMOS  SRAM. 
>>This, i believe, was the largest possible size in a 28-pin  format. Now, 
>>hopefully, I'd like to install a 32-pin SRAM in it's  place, which is 
>>organized as 512k x 8-bit (16 times the original  size). Aside from the 
>>top 2-pins on both sides of the 32-pin IC,  the rest of the pins line up 
>>with the original 28-pin SRAM.
>>
>>The difference between the two chips, besides the VCC being on a  
>>different pin, is that there is an additional (4) address  lines....... 
>>All other pins are compatible with the 28-pin version.
>>
>>Now, I'm no expert on how memory works.....but from my research it  seems 
>>like adding 4 spdt switches to control the highest 4 address  lines would 
>>give me (binary) access to switch between the 16 banks.  Is this correct?
>>
>>Aside from the additional banks, the newer SRAM would give data  retention 
>>of 10+ years because of an inbuilt lithium battery in the  IC.
>>
>
>I agree to what others already said, this surely will work. I did a  
>similar thing with my DX7 long long ago (replacing a 2k SRAM with an  8k 
>one).
>
>Does the unmodified sampler already keep its memory contents during  power 
>off? If not, it will probably overwrite the memory after power  up, or at 
>least the pointers to the samples or whatever. If the RAM  isn't battery 
>powered, the designers sure had done something to  prevent  the sampler 
>from generating ugly noises due to random memory  contents.
>OTOH, if the original design is already battery backed up, you'll  probably 
>be fine with RAMs without an internal battery. Perhaps you  have to replace 
>the original battery too because the sampler is so old.
>
>Ingo

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