Assembly Language Help (alang.hlp) (
Table of Contents;
Topic list)
Important Notice
The pages on this site contain documentation for very old MS-DOS software,
purely for historical purposes.
If you're looking for up-to-date documentation, particularly for programming,
you should not rely on the information found here, as it will be woefully
out of date.
REP Instruction
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────────────────────────────────────────────────────────────────────────────
11110011 1010010w
─────────────────────┬─────────────────────────┬────────────────────────────
REP MOVS dest,src │ rep movs source,dest │ 88/86 9+17n (W88=9+25n)
REP MOVSB [dest,src]│ rep movsw │ 286 5+4n
REP MOVSW [dest,src]│ │ 386 7+4n
REP MOVSD [dest,src]│ │ 486 12+3n
─────────────────────┴─────────────────────────┴────────────────────────────
11110011 1010101w
─────────────────────┬─────────────────────────┬────────────────────────────
REP STOS dest │ rep stosb │ 88/86 9+10n (W88=9+14n)
REP STOSB [dest] │ rep stos dest │ 286 4+3n
REP STOSW [dest] │ │ 386 5+5n
REP STOSD [dest] │ │ 486 7+4n
─────────────────────┴─────────────────────────┴────────────────────────────
11110010 1010110w
─────────────────────┬─────────────────────────┬────────────────────────────
REP LODS dest │ rep lodsb │ 88/86 ──
REP LODSB [dest] │ rep lods dest │ 286 ──
REP LODSW [dest] │ │ 386 ──
REP LODSD [dest] │ │ 486 7+4n
─────────────────────┴─────────────────────────┴────────────────────────────
11110011 0110110w
─────────────────────┬─────────────────────────┬────────────────────────────
REP INS dest,DX │ rep insb │ 88/86 ──
REP INSB [dest,DX] │ rep ins dest,dx │ 286 5+4n
REP INSW [dest,DX] │ │ 386 13+6n,pm=(7,27)+6n*
REP INSD [dest,DX] │ │ 486 16+8n,pm=(10,30)+8n*
─────────────────────┴─────────────────────────┴────────────────────────────
11110011 0110111w
─────────────────────┬─────────────────────────┬────────────────────────────
REP OUTS DX,src │ rep outs dx,source │ 88/86 ──
REP OUTSB [src] │ rep outsw │ 286 5+4n
REP OUTSW [src] │ │ 386 12+5n,pm=(6,26)+5n*
REP OUTSD [src] │ │ 486 17+5n,pm=(11,31)+5n*
─────────────────────┴─────────────────────────┴────────────────────────────
* First protected-mode timing: CPL <= IOPL. Second timing: CPL > IOPL.
5 if n = 0, 13 if n = 1.
5 if n = 0.
-♦-