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ROL: Difference between revisions

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'''ROL''' (Rotate Left) is a 65x instruction that rotates a value and the [[carry flag]] left one bit.  The most significant bit is shifted into the carry flag.  The carry flag is shifted into the least significant bit.  Except in [[accumulator addressing]], ROL takes two extra cycles when the accumulator is 16 bits wide. In [[direct page addressing]] modes, ROL takes another extra cycle if the low byte of the [[direct page register]] is nonzero.
'''ROL''' (Rotate Left) is a 65x instruction that rotates a value and the [[carry flag]] left one bit.  The most significant bit is shifted into the carry flag.  The carry flag is shifted into the least significant bit.   
 
===== Cycle Penalties =====
* Except in [[accumulator addressing]], ROL takes two extra cycles when the accumulator is 16 bits wide.
* In [[direct page addressing]] modes, ROL takes another extra cycle if the low byte of the [[direct page register]] is nonzero.


=== See Also ===
=== See Also ===

Revision as of 21:35, 20 November 2023

Basic Info
Addressing Mode Opcode Length Speed
Accumulator 2A 1 byte 2 cycles
Absolute 2E 3 bytes 6 cycles*
Direct Page 26 2 bytes 5 cycles*
absolute indexed by X 3E 3 bytes 7 cycles*
direct page indexed by X 36 2 bytes 6 cycles*
Flags Affected
N V M X D I Z C
. . . . .

ROL (Rotate Left) is a 65x instruction that rotates a value and the carry flag left one bit. The most significant bit is shifted into the carry flag. The carry flag is shifted into the least significant bit.

Cycle Penalties

See Also

External Links

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