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DESCRIPTION OF INSTRUCTIONS
335
76. MUL AB (Multiply accumulator by B)
10100100
70
Instruction code
Operations
Number of bytes
Number of cycles
Flags
(PSW)
Description
Example MUL AB(6AH × 15H=8B2H)
Instruction code
: Byte 1
(A)
0~7←(A) × (B)
(B)
8~15
:
C AC F0 RS1 RS0 OV F1 P
•••
:
:
:
The accumulator contents are multiplied by the arithmetic
operation register (B) contents. The operand is always handled
as an integer without sign. The lower order byte of the result is
placed in the accumulator, and the higher order byte is placed
in the arithmetic operation register (B). The carry flag is always
cleared. The overflow flag is set to 1 if the product is greater
than 00FFH, and to 0 in all other cases.
:
1
4
10100100
70
Byte 1
Accumulator
01101010
70
Before execution
Accumulator
10110010
70
After execution
:
Register B
00010101
70
Register B
00001000
70
0
Overflow flag
1
Overflow flag