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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out of date.
FCOM/FCOMP/FCOMPP/FICOM/FICOMP
◄Summary► ◄Timings►
────────────────┬─────────────────────────┬────────────────────────────────
FCOM [reg] │ fcom st(2) │ 87 40-50
│ fcom │ 287 40-50
│ │ 387 24
────────────────┼─────────────────────────┼────────────────────────────────
FCOMP [reg] │ fcomp st(7) │ 87 42-52
│ fcomp │ 287 42-52
│ │ 387 26
────────────────┼─────────────────────────┼────────────────────────────────
FCOMPP │ fcomp p │ 87 45-55
│ │ 287 45-55
│ │ 387 26
────────────────┼─────────────────────────┼────────────────────────────────
FCOM memreal │ fcom shortreals[di] │ 87 (s=60-70,l=65-75)+EA
│ fcom longreal │ 287 s=60-70,l=65-75
│ │ 387 s=26,l=31
────────────────┼─────────────────────────┼────────────────────────────────
FCOMP memreal │ fcomp longreal │ 87 (s=63-73,l=67-77)+EA
│ fcomp shorts[di] │ 287 s=63-73,l=67-77
│ │ 387 s=26,l=31
────────────────┼─────────────────────────┼────────────────────────────────
FICOM memint │ ficom double │ 87 (w=72-86,d=78-91)+EA
│ ficom warray[di] │ 287 w=72-86,d=78-91
│ │ 387 w=71-75,d=56-63
────────────────┼─────────────────────────┼────────────────────────────────
FICOMP memint │ ficomp WORD PTR [bp+6] │ 87 (w=74-88,d=80-93)+EA
│ ficomp darray[di] │ 287 w=74-88,d=80-93
│ │ 387 w=71-75,d=56-63
────────────────┴─────────────────────────┴────────────────────────────────
Condition Codes for FCOM
C3 C2 C1 C0 Meaning
0 0 ? 0 ST > source
0 0 ? 1 ST < source
1 0 ? 0 ST = source
1 1 ? 1 ST is not comparable to source
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