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Author Topic: Two quick assembly language questions  (Read 75 times)

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Offline taliadonTopic starter

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Two quick assembly language questions
« on: November 15, 2025, 11:34:21 AM »
Hey guys, two quick questions regarding 68000 programming:

1) Can anyone explain why move.w d0,-(a0) {8 Cycles} is faster than move.w -(a0),d0 {10 cycles}? This seems a weirdly asymmetrical to me.

2) Does anyone know why my version of Devpac doesn't like move.b a0,d0? Does this particular version of the move instruction have the same size limitations as movea{.w/.l} d0,a0? This is not stipulated within the documentation I have.

All comments are greatly appreciated.
 

Offline Thorham

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Re: Two quick assembly language questions
« Reply #1 on: November 15, 2025, 02:25:26 PM »
Answer to the second question is simple: 680x0 asm doesn't support byte operations on address registers.