Re: ZipGS more stable with slower SRAMS?

[rder@pro-palmtree.cts.com (Richard Der)]

Paul Schultz <pschultz@med.wayne.edu> wrote:
>Before I go out and buy slower SRAMS for my ZipGS, could someone
>explain why the ZipGS may be more stable at higher speeds with
>"not-so-fast" SRAMS in the DATA cache (around 35-45ns) instead
>of fast SRAMS (15ns)?
 
While I don't know why, it is true that the slower SRAMs work fine.
Consider a 10MHz unit upgraded from a 7MHz unit is extremely stable
with 70ns SRAMs.
 
JDR Microdevices has wide HM62256LP-70. These chips are 32k x 8,
70ns fast, and 600 mil wide. US $4.69. Perfect for the Zip GS.
 
JDR Microdevices: phone: 1-800-538-5000
                  fax: 1-800-538-5005
                  bbs: 1-408-494-1430
                  web: http://www.jdr.com
 
I have 4 of these chips in a 10/64 (upgraded from a 7MHz model).
They've been operating without a glitch for a year and a half and
still going.
 
JDR also has full TTL oscillators.
 
Don't know why the Zip FAQ writers claim you need even faster
SRAMs. The 7MHz models used to come with 100ns chips. This 10MHz
upgraded unit operates flawlessly with 70ns chips. Of course you
might need faster chips to move to 15MHz.


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