Static RAM chip source (& S-100 related questions...)

Glen Slick glen.slick at
Sun Aug 15 12:12:19 CDT 2010

On Sat, Aug 14, 2010 at 10:22 PM, Chuck Guzis <cclist at> wrote:
> On 14 Aug 2010 at 21:47, Josh Dersch wrote:
>> The board I'm populating needs 64 chips, but I'm only missing six of
>> them.  Is valid to assume that 2147s will play nicely with the
>> existing 5257s?  In that case the extra power consumption from 6 2147s
>> is probably not going to break the bank.
> I'd probably replace a row of 8, not just the 6.  The 2147 is a lot
> faster than the MM5257 (by about a factor of 5) which probably
> accounts for the difference in power consumption.  If you've got the
> power, you should be fine.
> --Chuck

One other thing that might help the situation is that the 2147 enters
an automatic power-down mode when the CE# input is at a high level.
For example the datasheet for the CY2147-35 says the max operating
current is 125ma while the max standby current is 25ma.

Do MM5257 parts enter a standby mode when not selected?  I don't have
a datasheet handy.  Which would draw more current total, two banks of
MM5257 parts, or two banks of CY2147 parts where at least one of the
two banks should be in standby mode?


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