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Posting-Version: version B 2.10.2 9/18/84; site watdcsu.UUCP
Path: utzoo!watmath!watnot!watdcsu!dmcanzi
From: dmcanzi@watdcsu.UUCP (David Canzi)
Newsgroups: net.micro.atari
Subject: Bus contention
Message-ID: <2048@watdcsu.UUCP>
Date: Mon, 27-Jan-86 23:28:28 EST
Article-I.D.: watdcsu.2048
Posted: Mon Jan 27 23:28:28 1986
Date-Received: Tue, 28-Jan-86 05:34:48 EST
Reply-To: dmcanzi@watdcsu.UUCP (David Canzi)
Organization: U of Waterloo, Ontario
Lines: 14

To refresh a 640 by 400 bit screen 70 times per second from memory 16
bits wide requires reading memory 1.12 million times per second.  It
takes 4 clock cycles (minimum) for the processor to read a word from
memory.  I would assume the same applies to the screen logic, *plus*
the time it takes to get control of the bus before reading, and
relinquish it after reading.  With an 8 megahertz clock, the screen
must be slowing down the processor by at least a factor of 2.

Or have I made a mistaken assumption somewhere?

-- 
David Canzi

Severeid's Law: The chief cause of problems is solutions.