Thread: 68k details
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Old 14 November 2018, 16:13   #776
roondar
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Join Date: Jul 2015
Location: The Netherlands
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Quote:
Originally Posted by Don_Adan View Post
Sorry, but sub.l and add.l instructions needs 6c, not 8c for 68000.
This is not correct AFAIK.

Code:
        Standard Instruction Execution Times
instruction    Size        op<ea>,An ^    op<ea>,Dn    op Dn,<M>
ADD          byte,word     8(1/0) +       4(1/0) +     8(1/1) +
              long         6(1/0) +**     6(1/0) +**   12(1/2)+

 notes:    
    + Add effective address calculation time
    ^ Word or long only
    * Indicates maximum value
    ** The base time of six clock periods is increased to eight        
       if the effective address mode is register direct or 
       immediate (effective address time should also be added)
This reads as 8 clocks for an add.l Dn,Dn command, unless I'm mistaken. I got this from: http://oldwww.nvg.ntnu.no/amiga/MC68...mstandard.HTML

The same figures can be found elsewhere as well. Strangely, the 'current' edition of the 68000 family programmers manual does not include cycle counts per instruction

Last edited by roondar; 14 November 2018 at 16:21.
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