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BBC (SPC700): Difference between revisions

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'''BBC''' (Branch on Bit Clear) is an [[SPC700]] instruction that performs a branch when a bit in the [[direct page]] is clear.  The direct page byte that bit lives in is the first operand.  The bit within that byte is a function of the high nibble of the opcode.  The target relative address to jump to is the second operand.
'''BBC''' (Branch on Bit Clear) is an [[SPC700]] instruction that performs a branch when a bit in the [[direct page]] is clear.  The index to the direct page byte that bit lives in is the first operand byteWhich bit within that byte is specified by the top 3 bits of the opcode.  The target relative address to jump to is the second operand byte.
 
In assembly source, the two operands appear in the same order that they do in the instruction stream.


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

Revision as of 20:37, 24 July 2023

Basic Info
Addressing Mode Opcode Length Speed
Direct Page 13 3 byte when condition is false: 5 cycles

when condition is true: 7 cycles

Direct Page 33 3 byte when condition is false: 5 cycles

when condition is true: 7 cycles

Direct Page 53 3 byte when condition is false: 5 cycles

when condition is true: 7 cycles

Direct Page 73 3 byte when condition is false: 5 cycles

when condition is true: 7 cycles

Direct Page 93 3 byte when condition is false: 5 cycles

when condition is true: 7 cycles

Direct Page B3 3 byte when condition is false: 5 cycles

when condition is true: 7 cycles

Direct Page D3 3 byte when condition is false: 5 cycles

when condition is true: 7 cycles

Direct Page F3 3 byte when condition is false: 5 cycles

when condition is true: 7 cycles

Flags Clobbered
N V P B H I Z C
. . . . . . . .

BBC (Branch on Bit Clear) is an SPC700 instruction that performs a branch when a bit in the direct page is clear. The index to the direct page byte that bit lives in is the first operand byte. Which bit within that byte is specified by the top 3 bits of the opcode. The target relative address to jump to is the second operand byte.

In assembly source, the two operands appear in the same order that they do in the instruction stream.

See Also

External Links