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From: kff@kesmai.COM (Kelton Flinn)
Newsgroups: comp.sys.mac
Subject: Re: Mac II graphics weirdities
Summary: Why there are little duplicate images...
Keywords: Small, *4, Color
Message-ID: <212@kesmai.COM>
Date: 4 May 89 04:23:46 GMT
References: <1531@jhunix.HCF.JHU.EDU> <8264@chinet.chi.il.us> <492@biar.UUCP> <13121@paris.ics.uci.edu>
Distribution: usa
Organization: Kesmai Corporation, Charlottesville, VA
Lines: 19

In article <13121@paris.ics.uci.edu>, milne@ics.uci.edu (Alastair Milne) writes:
>Question for the day:  I've got a mac II here and have found that certain
>graphics intensive programs (macpaint for the SE, Talking Moose, Dungeon
>of Doom) Draw everything ok except the working area (thing being drawn)
>which appears 
>seriously smallified in four scaled down ~1"x1" squares spread out along
>the menu bar.
>
    This is caused not by applications accessing memory at the wrong
address, but by accessing memory in the wrong FORMAT. The aforementioned
programs ASSUME that pixels consist of one bit, whereas in fact they
consist of 1, 2, 4 or 8 bits, depending on the graphics mode you set with
the Control Panel. Since the window frames and so on are drawn using
Quickdraw, they are drawn correctly. Anything the application does by
bypassing the ROM routines and accessing the memory directly comes out
wrong. Why do they do this? Generally speed. How do you fix it? Set the
monitor to monochrome using the Control Panel and it'll work perfectly,
unless they've broken even worse rules <grin>.
    Kelton