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BVC: Difference between revisions
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'''BVC''' is a 65x instruction that performs a branch if the [[overflow flag]] is clear. | '''BVC''' is a 65x instruction that performs a branch if the [[overflow flag]] is clear. If the overflow flag is set, control simply falls through to the next instruction. | ||
No flags are affected. | No flags are affected. | ||
Revision as of 11:50, 14 July 2024
| Basic Info | |||||||
|---|---|---|---|---|---|---|---|
| Addressing Mode | Opcode | Length | Speed | ||||
| Program Counter Relative | 50 | 2 bytes | 2 cycles* | ||||
| Flags Affected | ||||||||
|---|---|---|---|---|---|---|---|---|
| N | V | M | X | D | I | Z | C | |
| . | . | . | . | . | . | . | . | |
BVC is a 65x instruction that performs a branch if the overflow flag is clear. If the overflow flag is set, control simply falls through to the next instruction.
No flags are affected.
Syntax
BVC label
Cycle Penalties
- BVC takes one extra cycle if the branch is taken
- BVC takes another extra cycle if that branch taken crosses a page boundary in emulation mode.
See Also
External Links
- Eyes & Lichty page 439 on BVC: https://archive.org/details/0893037893ProgrammingThe65816/page/n465
- Labiak page 128 on BVC: https://archive.org/details/Programming_the_65816/page/n138
- MCS6500 Manual page 41 on BVC: https://archive.org/details/mos_microcomputers_programming_manual/page/n56
- Carr page 252 on BVC: https://archive.org/details/6502UsersManual/page/n265
- Leventhal page 3-51 on BVC: https://archive.org/details/6502-assembly-language-programming/page/n100
- snes9x implementation of BVC: https://github.com/snes9xgit/snes9x/blob/master/cpuops.cpp#L1395