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The 8051 Instruction Set

1-35 Atmel 8051 Microcontrollers Hardware Manual

4316E–8051–01/07

1.14.14 DIVAB

Function: Divide

Description: DIV AB divides the unsigned eight-bit integer in the Accumulator by the unsigned eight-bit integer in register B.

The Accumulator receives the integer part of the quotient; register B receives the integer remainder. The carry

and OV flags are cleared.

Exception: if B had originally contained 00H, the values returned in the Accumulator and B-register are

undefined and the overflow flag are set. The carry flag is cleared in any case.

Example: The Accumulator contains 251 (0FBH or 11111011B) and B contains 18 (12H or 00010010B). The following

instruction,

DIV AB

leaves 13 in the Accumulator (0DH or 00001101B) and the value 17 (11H or 00010001B) in B, since

251 = (13 x 18) + 17. Carry and OV are both cleared.

Bytes: 1

Cycles: 4

Encoding: 1 0 0 0 0 1 0 0

Operation: DIV

(A)

15-8

← (A)/(B)

(B)

7-0

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Atmel C51 Handbuch Seite 37