Integer Instructions
4-186 M68000 FAMILY PROGRAMMER’S REFERENCE MANUAL MOTOROLA
TAS Test and Set an Operand TAS
(M68000 Family)
Operation: Destination Tested → Condition Codes; 1 → Bit 7 of Destination
Assembler
Syntax: TAS < ea >
Attributes: Size = (Byte)
Description: Tests and sets the byte operand addressed by the effective address field. The
instruction tests the current value of the operand and sets the N and Z condition bits
appropriately. TAS also sets the high-order bit of the operand. The operation uses a
locked or read-modify-write transfer sequence. This instruction supports use of a flag
or semaphore to coordinate several processors.
Condition Codes:
X — Not affected.
N — Set if the most significant bit of the operand is currently set; cleared otherwise.
Z — Set if the operand was zero; cleared otherwise.
V — Always cleared.
C — Always cleared.
Instruction Format:
XNZVC
—∗∗00
1514131211109876543210
0100101011
EFFECTIVE ADDRESS
MODE REGISTER
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