Re: Last ZipGS RAM question...

[Paul Schultz <pschultz@med.wayne.edu>]

On Fri, 12 Feb 1999, Martin Gruen wrote:

> 
> So it seems that no one has been able to answer the question of which 32x8
> SRAM the zip needs.  
> 
> Can someone at least point me toward a company's part # for a 15ns (Wide)
> chip that they know will work?
> 
> 

It will be VERY difficult to find 15ns _wide_ SRAMs for your
ZipGS. All the SRAMs available today in this speed range are
the narrow (skinny) chips which are 0.3 inches wide.

Unfortunately, the ZipGS has sockets for 0.6 inch chips. To
add the ability to use skinny SRAMs you will need to solder
in a modification. The most common mod (and most versatile)
is to buy some sockets and cut them so that you end up with
a single row of socket pin connectors. Then you need to cut
the middle cross pieces from the wide sockets on your ZipGS
(this can be done with a sharp utility knife with the blade
slightly heated; or with some toe nail clippers). This will
expose a row of pin holes on the IC board which will accept
the single row of socket connectors you made above.

So, you will end up with a socket position on your ZipGS
with the capability to handle either wide or skinny SRAMS.
Don't worry about the sockets being 'flimsy' after cutting
away the middle plastic pieces. They remain sturdy since
they have 14 pins soldered to the IC board. This soldering
should be done by someone familiar with soldering IC boards.

Here is some ASCI art depicting one socket before and after
modification:

 BEFORE:             AFTER:
 =======             =======
 _       _           _   _   _
|o|     |o|         |o| |o| |o|
|o|_____|o|         |o| |o| |o|
|o _____ o|         |o| |o| |o|
|o|     |o|         |o| |o| |o|
|o|     |o|         |o| |o| |o|
|o|     |o|         |o| |o| |o|
|o|     |o|         |o| |o| |o|
|o|     |o|         |o| |o| |o|
|o|     |o|         |o| |o| |o|
|o|     |o|         |o| |o| |o|
|o|_____|o|         |o| |o| |o|
|o _____ o|         |o| |o| |o|
|o|     |o|         |o| |o| |o|
|o|     |o|         |o| |o| |o|
 ~       ~           ~   ~   ~
   ^^^^^                ^^^
  Cut these off!     Add this strip of socket.

Hope this helps. If you don't feel comfortable doing this
mod try to find someone to do it for you. Or, I do know
there are 35 to 45ns wide SRAMs available but you will
really have to hunt for them. They seem to be scarce.

For the skinny SRAMS you can try Jameco (www.jameco.com).
They have 15ns 32 x 8 SRAMs. Most other IC/memory vendors
also carry the SRAMs.

Paul.

pschultz@med.wayne.edu
Paul Schultz