BBS (SPC700)

Basic Info
Addressing Mode	Opcode	Length	Speed
Direct Page Bit Relative	03	3 bytes	when condition false: 5 cycles when condition true: 7 cycles
Direct Page Bit Relative	23	3 bytes	when condition false: 5 cycles when condition true: 7 cycles
Direct Page Bit Relative	43	3 bytes	when condition false: 5 cycles when condition true: 7 cycles
Direct Page Bit Relative	63	3 bytes	when condition false: 5 cycles when condition true: 7 cycles
Direct Page Bit Relative	83	3 bytes	when condition false: 5 cycles when condition true: 7 cycles
Direct Page Bit Relative	A3	3 bytes	when condition false: 5 cycles when condition true: 7 cycles
Direct Page Bit Relative	C3	3 bytes	when condition false: 5 cycles when condition true: 7 cycles
Direct Page Bit Relative	E3	3 bytes	when condition false: 5 cycles when condition true: 7 cycles

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

BBS (Branch on Bit Set) is an SPC700 instruction that performs a branch when a bit in the direct page is set. The index to the direct page byte that bit lives in is the first operand byte. Which bit within that byte is a specified by the top 3 bits of the opcode. The target relative address to jump to is the second operand byte. In Nintendo's manual, the high nybble of the opcode is called x.

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

No flags are affected.

Syntax

BBS dp, bit, rel

See Also

• BBC

References

• Table C-15, Appendix C-8 of Book I of the official Super Nintendo development manual
• anomie: https://github.com/yupferris/TasmShiz/blob/8fabc9764c33a7ae2520a76d80ed7220bb939f12/spc700.txt#L349