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Path: utzoo!watmath!watcgl!jchapman
From: jchapman@watcgl.UUCP (john chapman)
Newsgroups: net.micro.68k
Subject: Re: seeking advice on dynamic memory controller
Message-ID: <1476@watcgl.UUCP>
Date: Sat, 16-Mar-85 13:07:23 EST
Article-I.D.: watcgl.1476
Posted: Sat Mar 16 13:07:23 1985
Date-Received: Sun, 17-Mar-85 01:12:59 EST
References: <421@umd5.UUCP>
Distribution: na
Organization: U of Waterloo, Ontario
Lines: 26

> Hello!  I've got a little project going on at home with a Motorola
> 68000 Educational Computer Board.  This is a single board 68K with
> 32K bytes of 4116 type memories, organized as 16K x 16bits.  The 68K
> is running at 4MHz.
> 
> I find that I need more than 32K of memory, and have been considering
> adding 128K (16 4164 devices).  I can't replace the existing 32K of
> memory since it runs from 0x0000 to 0x7FFF, and there is a ROM monitor
> addressed starting at 0x8000.  It doesn't seem practical to use the
> existing dynamic RAM refresh logic and address multiplexors.  I was
> considering a design using the Intel 8203 dynamic RAM controller.  Is
> this a good idea?  Are there any alternatives that I should look into?
> -- 
> --
> Louis A. Mamakos WA3YMH   University of Maryland, Computer Science Center

 The 8203 is very easy to design with and does just about everything
 you would want; it is, however, slow - a board designed with 150ns
 drams will probably end up with a board access time of around 450ns.
 This may not be a problem in your case.  I think the 8203 is a little
 bit easier to work with (takes care of more details) than other
 easily available chips I have seen.  TI apparently has a similar
 chip but I don't know anything about it (if someone would post or
 mail me details on it I would be interested: thanks).
 
 John