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documentation, particularly for programming, you should not rely on the information found here, as it will be woefully out of date.

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 10011000*
─────────────────┬─────────────────────────┬────────────────────────────────
 CBW             │ cbw                     │ 88/86 2
                 │                         │   286 2
                 │                         │   386 3
                 │                         │   486 3
─────────────────┼─────────────────────────┼────────────────────────────────
 CWDE            │ cwde                    │ 88/86 ──
                 │                         │   286 ──
                 │                         │   386 3
                 │                         │   486 3
─────────────────┴─────────────────────────┴────────────────────────────────
 
 10011001*
─────────────────┬─────────────────────────┬────────────────────────────────
 CWD             │ cwd                     │ 88/86 5
                 │                         │   286 2
                 │                         │   386 2
                 │                         │   486 3
─────────────────┼─────────────────────────┼────────────────────────────────
 CDQ             │ cdq                     │ 88/86 ──
                 │                         │   286 ──
                 │                         │   386 2
                 │                         │   486 3
─────────────────┴─────────────────────────┴────────────────────────────────
  * CBW and CWDE have the same encoding, and CWD and CDQ have the
    same encoding. The only difference is that in 32-bit mode CBW and
    CWD are preceded by the operand-size byte (66h), but CWDE and CDQ
    are not.
 
    In 16-bit mode, CWDE and CDQ are preceded by the operand-size byte,
    but CBW and CWD are not.
                                    -♦-