Path: utzoo!mnetor!uunet!yale!wallman-george
From: wallman-george@CS.YALE.EDU (Natuerlich!)
Newsgroups: comp.sys.atari.st
Subject: Re: Screen memory format
Message-ID: <25904@yale-celray.yale.UUCP>
Date: 27 Mar 88 20:29:43 GMT
References: <8803271924.AA18903@ucbvax.Berkeley.EDU>
Sender: root@yale.UUCP
Reply-To: wallman-george@CS.YALE.EDU (Natuerlich!)
Organization: Natuerlich!'s Software Vault #5 -- Location Yale
Lines: 24

>I need to know what the format of the ST display memory is.  The Abacus
>Internals book gives a completely different discription than the Compute!'s
>VDI manual.  I tend to trust the Compute! publication more because it
>sounds a lot more reasonable and intelligent. (Let's talk low-res here)
>
>Compute!:  Each ADJACENT four BITS specify a number between 0 and 15
>           that represents the color register used to plot that pixel.
>Abacus:    Four contiguous memory WORDS specify the color of 16 pixels.
>           To set a pixel, one must set a bit in each of the four words.
>           "in order to set the point in the upper left-hand corner,
>           the topmost bits of words $78000 (assume screen memory starts
>           at 78000), $78002, $78004, and $78006 must be manipulated."
>
>Like I said, the Abacus method doesn't sound very logical.
>Which method is actually used?

The less reasonable and intelligent method has been used
(to keep the hardware simpler and/or faster, I believe). 

Natuerlich!
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