Re: ZipGS more stable with slower SRAMS?

[martin.kaeser@auge.de]

From: martin.kaeser@auge.de
Subject: Re: ZipGS more stable with slower SRAMS?
Date: Sat, 20 Jul 1996 02:53:58 +0000

Paul Schultz 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)?

Our local expert told me:

The Zip first reads the Tag RAM and then the Data RAM. 
At speeds > 10 MHz, it gets the timing wrong. The Tag RAM is still 
driving data on the bus and the Data RAM is beginning to put data on
the 
same bus corrupting data.

Using a slower Data RAM gives the tag ram more time to get off the bus.

My Zip is "unsafe at any speed" using 15ns SRAMs. It crashes at 7MHz 
with the same frequency as with 16.5 MHz.

 I have no idea where to look for 45ns SRAMs and i think i�ll put a TTL 
driver chip on my Zip to delay the chip enable of the Data RAMs. Did 
anybody try this?

martin


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