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BCC: Difference between revisions
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{| class="wikitable" style="float:right;clear:right;width:40%" | |||
{| class="wikitable" style="float:right;clear:right;width: | |||
!colspan="8"|Basic Info | !colspan="8"|Basic Info | ||
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|'''Speed''' | |'''Speed''' | ||
|+ | |+ | ||
| | |[[Program Counter Relative]] | ||
|90 | |90 | ||
|2 | |2 bytes | ||
|2 cycles | |2 cycles* | ||
|} | |} | ||
{| class="wikitable" style="float:right;clear:right;width:30%" | {| class="wikitable" style="float:right;clear:right;width:30%" | ||
!colspan="9"|Flags | !colspan="9"|Flags Affected | ||
|+ | |+ | ||
|N | |[[Negative Flag|N]] | ||
|V | |[[Overflow Flag|V]] | ||
|M | |[[M Flag|M]] | ||
|X | |[[X Flag|X]] | ||
|D | |[[Decimal Flag|D]] | ||
|I | |[[I Flag|I]] | ||
|Z | |[[Zero Flag|Z]] | ||
|C | |[[Carry Flag|C]] | ||
|+ | |+ | ||
|. | |. | ||
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|. | |. | ||
|} | |} | ||
'''BCC''' (Branch if Carry Clear) is a 65x instruction that performs a jump if the [[carry flag]] is clear. An alternate mnemonic is "BLT." | |||
If carry is set, control simply falls through to the next instruction. | |||
No flags are affected. | |||
==== Syntax ==== | |||
<pre> | |||
BCC nearlabel | |||
BLT nearlabel | |||
</pre> | |||
==== Cycle Penalties ==== | |||
* BCC takes one additional cycle if the branch is taken | |||
* BCC takes another extra cycle in [[emulation mode]] if that branch taken crosses a page boundary. | |||
=== See Also === | === See Also === | ||
* [[BCS]] | * [[BCS]] | ||
* [[XCE]] | |||
* [[BCC (Super FX)]] | |||
* [[BLT (Super FX)]] | |||
=== External Links === | |||
* [[Eyes & Lichty]], [https://archive.org/details/0893037893ProgrammingThe65816/page/428 page 428] on BCC | |||
* [[Labiak]], [https://archive.org/details/Programming_the_65816/page/n128 page 118] on BCC | |||
* 4.1.2.3 on [[MCS6500 Manual]], [https://archive.org/details/mos_microcomputers_programming_manual/page/n55 page 40] on BCC | |||
* [[Carr]], [https://archive.org/details/6502UsersManual/page/n261 page 248] on BCC | |||
* [[Leventhal]], [https://archive.org/details/6502-assembly-language-programming/page/n92 page 3-43] on BCC | |||
* snes9x implementation of BCC: https://github.com/snes9xgit/snes9x/blob/master/cpuops.cpp#L1360 | |||
[[Category:ASM]] | [[Category:ASM]] | ||
[[Category:Inherited from 6502]] | [[Category:Inherited from 6502]] | ||
[[Category:Conditional Branches]] | |||
[[Category:Two-byte Instructions]] | |||
[[Category:Two-cycle Instructions]] | |||
Latest revision as of 02:37, 10 August 2024
| Basic Info | |||||||
|---|---|---|---|---|---|---|---|
| Addressing Mode | Opcode | Length | Speed | ||||
| Program Counter Relative | 90 | 2 bytes | 2 cycles* | ||||
| Flags Affected | ||||||||
|---|---|---|---|---|---|---|---|---|
| N | V | M | X | D | I | Z | C | |
| . | . | . | . | . | . | . | . | |
BCC (Branch if Carry Clear) is a 65x instruction that performs a jump if the carry flag is clear. An alternate mnemonic is "BLT."
If carry is set, control simply falls through to the next instruction.
No flags are affected.
Syntax
BCC nearlabel BLT nearlabel
Cycle Penalties
- BCC takes one additional cycle if the branch is taken
- BCC takes another extra cycle in emulation mode if that branch taken crosses a page boundary.
See Also
External Links
- Eyes & Lichty, page 428 on BCC
- Labiak, page 118 on BCC
- 4.1.2.3 on MCS6500 Manual, page 40 on BCC
- Carr, page 248 on BCC
- Leventhal, page 3-43 on BCC
- snes9x implementation of BCC: https://github.com/snes9xgit/snes9x/blob/master/cpuops.cpp#L1360