From: Sylvan Butler
Subject: Re: help stacking RAM
Date: Fri, 25 Oct 2002 16:26:28 -0600
User-Agent: slrn/0.9.7.3 (Linux)
On Fri, 25 Oct 2002 09:10:27 GMT, John DeGroof wrote:
> I have a portable MP3 player with 8MB of buffer RAM (not data
> storage), and want to double it to 16MB due to a limitation I've
> reached. Someone else has confirmed the firmware will autodetect up
> to 16MB. The problem I'm having is it uses EDO DRAM, and I can't find
> a 128Mb/16MB pin-for-pin replacement, so the thought of stacking chips
Of course it cannot be pin-for-pin, because the 2x storage increase
requires an additional address line. That is also a problem with
stacking. Does the board fully decode the memory? Is there an
enable used to gate the existing memory, and a corresponding enable*
you can use to gate the added memory? Or how will you select which
bank of memory? Once you solve that, I wouldn't be too worried
about current, but physical size might be an issue. Do the chips
generate any noticable heat? Usually not, but if they do it might
be a problem.
> I'd be thankful to anyone who could guide me through the procedure of
> stacking chips to double memory. I have SMD soldering experience, and
> have designed and built small simple circuits.
Basically solder all pins to the chip below, except for the enable
pin. That needs to be tied to an inverted version of the signal on
the original banks enable.
OTOH, I haven't stacked chips since the DIP package days of 64kbit
and 256kbit chips. :)
| Sylvan Butler | Not speaking for Hewlett-Packard | sbutler-boi.hp.com |
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