Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!csd4.milw.wisc.edu!dogie.macc.wisc.edu!uwvax!tank!ra_robert@gsbacd.uchicago.edu
From: ra_robert@gsbacd.uchicago.edu
Newsgroups: comp.sys.mac.programmer
Subject: Really basic assembly language question: moving words from mem. and reg.
Message-ID: <3475@tank.uchicago.edu>
Date: 27 May 89 20:44:50 GMT
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Organization: University of Chicago Graduate School of Business
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I've been reading Knaster's book and in the intro to assembly language section
he says: 

"If a .W suffix is used with a memory location, the word is taken from the byte
addressed and the one immediately following it...If the operand is a register,
the lower word of the register is used, ignoring the upper word".

OK, so let's say you have the long word $44 99 85 6C at memory location $100. 
So, the byte at $100 is $44 and the byte at $101 is 99, right?   Let's say you
also have this long word in register D0.  Now if you move a word (MOVE.W) from
memory location $100 to somewhere else, you'll be moving $44 99, right?  And if
you move a word (MOVE.W) from D0, you'll be moving $85 6C.  So with a MOVE.W
instruction, what you're moving depends on whether you're moving from a memory
location or from a register, right?

I'm an assembly language novice (as you can tell).  Any info much appreciated.

 
Robert
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ra_robert@gsbacd.uchicago.edu
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generic disclaimer: all my opinions are mine