Path: utzoo!utgpu!water!watmath!clyde!rutgers!mit-eddie!bloom-beacon!think!ames!pasteur!ucbvax!MTUS5.BITNET!MCCABE
From: MCCABE@MTUS5.BITNET
Newsgroups: comp.sys.atari.st
Subject: Screen memory format
Message-ID: <8803271924.AA18903@ucbvax.Berkeley.EDU>
Date: 27 Mar 88 19:08:00 GMT
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The Internet
Lines: 28

Date:    27 March 1988, 13:56:33 EST
From:    Jim McCabe                                      MCCABE at MTUS5
To:      INFO-ATARI16 at SCORE.STANFORD.EDU
Subject: Screen memory format

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?

Thanks in advance!

+-----------------------+-----------------------------+
|  Jim McCabe           |  BITNET:  mccabe   @ mtus5  |
|  G31 ECH MTU          |           jemccabe @ mtus5  |
|  Houghton, MI  49931  |    UUCP:  mccabe   @ m-net  |
+-----------------------+-----------------------------+