CompuServe Messages

#Tell me about OS-9

    10-Mar-89 12:20:42
Fm: Peter Smithem 71001,3663
To: M2S/Phil Camp 76004,2054
On the 68000 the MOVEM.L would give you alot more speed. You'll have to excuse me, I spend most of my time programming 68020's and tend to forget that the 68000 doesn't have an instruction cache, which drastically alters the instruction timing. On the '020, assuming you use the 8 data registers, moving 8 long words via a pair of MOVEM.L instructions takes 80 clocks, best case. An unfolded loop with 8 MOVE.L An+,An+ takes 56. Doing the same thing on the 68000, the MOVEM.L's take 152 clocks and the unfolded loop takes 160.