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BIT: Difference between revisions

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(n and v flag behavior)
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'''BIT''' is a 65x instruction that performs a logical AND operation between the [[accumulator]] and memory without storing the conjunction.
'''BIT''' is a 65x instruction that performs a logical AND operation between the [[accumulator]] and memory without storing the conjunction.


Except in [[immediate addressing]], the most significant bit of the data located at the effective address is moved into the [[negative flag]], and the second most significant bit of that data is moved into the [[overflow flag]].
Except in [[immediate addressing]], the most significant bit of the data located at the effective address is moved into the [[negative flag]], and the second most significant bit of that data is moved into the [[overflow flag]].  BIT is often used right before a conditional branch instruction.


===== Cycle Penalties =====
===== Cycle Penalties =====
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=== See Also ===
=== See Also ===
* [[AND]]
* [[AND]]
* [[BPL]]
* [[BNE]]
* [[BCC]]
* [[BCS]]
* [[BVC]]
* [[BVS]]


=== External Links ===
=== External Links ===

Revision as of 03:31, 25 November 2023

Basic Info
Addressing Mode Opcode Length Speed
Immediate 89 2 bytes* 2 cycles*
Absolute 2C 3 bytes 4 cycles*
Direct Page 24 2 bytes 3 cycles*
absolute indexed X 3C 3 bytes 4 cycles*
direct page indexed X 34 2 bytes 4 cycles*
Flags Affected
Addressing Mode N V M X D I Z C
Immediate . . . . . . .
other . . . . .

BIT is a 65x instruction that performs a logical AND operation between the accumulator and memory without storing the conjunction.

Except in immediate addressing, the most significant bit of the data located at the effective address is moved into the negative flag, and the second most significant bit of that data is moved into the overflow flag. BIT is often used right before a conditional branch instruction.

Cycle Penalties

See Also

External Links