Newsgroups: comp.robotics
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From: arasv@tplrd.tpl.oz.au (Aras Vaichas)
Subject: Extra RAM
Message-ID: <1995Feb9.160003.1701@sydrd15.tplrd.tpl.oz.au>
Originator: arasv@sydrd108
Lines: 32
Nntp-Posting-Host: sydrd108
Organization: Telectronics Pacing Systems
Date: Thu, 09 Feb 95 04:54:15 GMT

It is best used for large contiguous memory storage, say,
for data collection, CCD images etc.

This uses 2-3 I/O ports: data IN/OUT, strobe, CLK.

You need: a binary counter and a 1bit-by-XXXXXbytes
S/RAM chip.

The CLK (from the 68hc11) clocks over the binary
counter which gives an address to the S/RAM. The S/RAM's
1bit output then can be inputted to the 68hc11 as data
and put into Xbit words sequentially.

Yes this is slow and equivalent to an old magnetic tape
streamer!! But it uses simple (and few) components, and
would be good for storing a map of a maze, etc. And take
the load off limited on-board RAM. Perhaps another output
can be used to up/down count the binary counter to speed
things up a little.

I'm not sure about the strobe, it depends if you wish to
write data back to the serial S/RAM.

Pointers will be needed to keep track of data positions.

Aras Vaichas

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