Re: nvram expansion ???
Jeff Walther <trag <at> io.com>
2003-05-07 02:11:33 GMT
At 11:49 -0700 05/06/2003, Henry B. Hotz wrote:
>At 2:32 PM -0400 5/6/03, kevdig <at> rcn.com wrote:
>>A while back someone posted a message about upgrading nvram?
>>Is this possible? If I remember correctly, the machine in
>>question was the same one I use, an 8600? Comments from
>>someone at Apple VERY welcome. Thanks!
>It wasn't anyone at Apple. If I had to guess I'd say it was John
>Klos <john <at> ziaspace.com>, but I could be wrong.
I think it was me. However, the machine in question was not an
8600, it was basically any machine in the PowerSurge family (7500 -
9600, 7300, plus relevant clones and ANS).
What I found was that replacing the NVRAM chip with a larger capacity
pin compatible chip does not appear to increase the NVRAM capacity.
The NVRAM chip is a small 8K X 8 SRAM chip. I replaced it with a 32K
X 8 SRAM chip.
After replacement, the NVRAM still functioned properly, but as far as
I could tell, the NVRAM capacity remained the same. There was some
ambiguity in my tests, as I'm not certain the method I used reported
measured NVRAM capacity or simply reported what the software expected
the machine in question to have. I don't remember how I performed
the test any more, so I can't be more specific. I do remember that
I thought I was testing actual NVRAM capacity and that I went through
minor gymnastics to get around the "expected result reported" issue.
There could be a few reasons for this. Apple may not have
implemented the extra address lines needed to support a larger chip.