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From: farren@gethen.UUCP (Michael J. Farren)
Newsgroups: comp.sys.amiga
Subject: Re: Monitor mishmash
Message-ID: <251@gethen.UUCP>
Date: Sun, 25-Oct-87 05:13:57 EST
Article-I.D.: gethen.251
Posted: Sun Oct 25 05:13:57 1987
Date-Received: Tue, 27-Oct-87 02:55:56 EST
References: <3113@ccicpg.UUCP> <2530@cbmvax.UUCP> <1774@dino.cpe.ulowell.edu> <3248@ccicpg.UUCP> <2595@cbmvax.UUCP>
Reply-To: farren@gethen.UUCP (Michael J. Farren)
Organization: Sci-Fido - Unix in Oakland
Lines: 26
Keywords: Interlace, monitors, scan doublers

In article <2595@cbmvax.UUCP> hedley@cbmvax.UUCP (Hedley Davis) writes:
>I think you need fast rams. If you can do it using low bandwidth rams
>( IE normal DRAMS ( not video shift register rams )), for less cost
>than the neccesary number of video shift register rams, I am sure
>many people here as well as all the other computer companies would be
>very interested.

It's definitely possible, and, in fact, is easy.  120ns?  Hell, you 
could probably use 250ns RAM with ease.  Remember, you are not con-
strained by requiring the CPU to be able to access the RAMs, so you
could design them as a 6-bit deep array, and load/read all six bit
planes at once.  This would reduce your bandwidth by six times;  the
scan conversion would use twice the bandwidth; net result, three times
less bandwidth required than for "normal" video.  The difficulty with
this scheme is that you have to use a lot more RAM chips, but you get
paid back by the fact that you could use smaller RAMs, which are con-
siderably more than four times cheaper than either video RAMs or
60ns dynamics.  You could even use CMOS RAM and save a lot of power
and heat.  Don't know what the tradeoffs would be, exactly, but I'm
willing to bet that you could design a winning card like this.


-- 
----------------
Michael J. Farren      "... if the church put in half the time on covetousness
unisoft!gethen!farren   that it does on lust, this would be a better world ..."
gethen!farren@lll-winken.arpa             Garrison Keillor, "Lake Wobegon Days"