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From: graeme@research.canon.oz.au (Graeme Wong See)
Newsgroups: sci.electronics
Subject: Re: Refreshing DRAM
Message-ID: <1990Nov5.063219.2266@research.canon.oz.au>
Date: 5 Nov 90 06:32:19 GMT
References: <1445.272CBD1B@ofa123.fidonet.org> <1990Oct31.194436.28242@idt.unit.no>
Sender: graeme@research.canon.oz.au (Graeme Wong See)
Reply-To: graeme@research.canon.oz.au (Graeme Wong See)
Organization: Canon Information Systems Research Australia
Lines: 38

In article <1990Oct31.194436.28242@idt.unit.no> thoger@solan.unit.no writes:
>In article <1445.272CBD1B@ofa123.fidonet.org>, rick@ofa123.fidonet.org (Rick Ellis) writes:
>|> 
>|>  > If one increases the amount of DRAM by a factor of
>|>  > 4, say, does this mean that the microprocessor spends 4 times as much time
>|>  > refreshing, and hence, less time executing useful instructions? 
>|> 
>|> No.  Refresh is done in parallel.
>|>  
>|> 
>|> --  
>|> Rick Ellis
>|> Internet: rick@ofa123.fidonet.org
>|> Compuserve: >internet:rick@ofa123.fidonet.org
>|> BBS: 714 939-1041
>|> --------------------------------------------------------------------------
>
>Hmm..
>In an old (autumn 1987) issue of BYTE they were testing 12 exTended memory 
>expansion board. They measured and published figures for how much each board
>slowed down the system, just by being installed... They even got different
>figures for each board... They claimed that this slowdown was due to the extra
>time it takes to refresh the extra RAM.
>
>I don't know much about this, but that's what the article said.. ( I read this
>a week or so ago, so I'm sure about it..)
>
>	-Terje

Quite possibly because the AT Bus is running at 8MHz, so refreshing that DRAM
takes longer than refreshing DRAM on the motherboard which can be refreshed
at a greater speed.

graeme.
-- 
Graeme Wong See, Hardware Engineer           | Net:  graeme@research.canon.oz.au
Canon Information Systems Research Australia | Phone: +1 61 2 805 2912
P.O. Box 313 North Ryde, NSW, Australia 2113 | Fax:   +1 61 2 805 2929