Xref: utzoo comp.sys.mac.hardware:9010 sci.electronics:18111
Newsgroups: comp.sys.mac.hardware,sci.electronics
Path: utzoo!henry
From: henry@zoo.toronto.edu (Henry Spencer)
Subject: Re: Why SRAMS in Mac Laptops?
Message-ID: <1991Mar1.163834.28207@zoo.toronto.edu>
Organization: U of Toronto Zoology
References: <1991Mar1.020935.7107@dartvax.dartmouth.edu>
Date: Fri, 1 Mar 1991 16:38:34 GMT

In article <1991Mar1.020935.7107@dartvax.dartmouth.edu> watt@eleazar.dartmouth.edu (Gill Watt) writes:
>Why do the mac laptops use SRAMS instead of the standard DRAMS?
>Is it because DRAM refresh circuitry consumes a lot more
>power?  If so, how much more?

It's not the refresh circuitry so much as the DRAMs themselves.  DRAMs
simply are not low-power technology.  The right sort of SRAMs are.

There is no single meaningful answer to "how much more".  It can be orders
of magnitude, if you really work at making the SRAM system economical.
In particular, where DRAMs draw milliamps, SRAMs in low-voltage standby
typically draw nanoamps.
-- 
"But this *is* the simplified version   | Henry Spencer @ U of Toronto Zoology
for the general public."     -S. Harris |  henry@zoo.toronto.edu  utzoo!henry