HuC6280 Instruction Set

From Archaic Pixels
Jump to: navigation, search

Contents

ADC - Add with Carry

N V T D I Z C
 ?  ? 0  ?  ?

Add the value specified by the operand, and 1 if the Carry flag is set, to the value in the accumulator. If the result is too large to fit in the accumulator, the carry flag will be set, otherwise it will be cleared.

If the Decimal-mode CPU flag is set, an extra cycle will be taken(*confirmed with Immediate mode only, however, other addressing modes need to be tested, but should yield the same result).

The overflow flag is not affected by this instruction if in Decimal mode; otherwise, if bit7 of the result != bit7 of the accumulator before the operation, and bit7 of the accumulator before the operation == bit7 of the value specified by the operand, the overflow flag is set, otherwise it is cleared. In other words, if we were to treat the accumulator and value specified by the operand as two's complement numbers, in the range of -128 to 127, the overflow flag will be set if the end result is outside of this range(otherwise it will be cleared).

Addressing Mode Syntax Opcode Bytes Cycles
Immediate ADC #$ii $69 2 2
Zero Page ADC $zz $65 2 4
Zero Page, X ADC $zz,X $75 2 4
Absolute ADC $aaaa $6d 3 5
Absolute, X ADC $aaaa,X $7d 3 5
Absolute, Y ADC $aaaa,Y $79 3 5
Indirect ADC ($zzzz) $72 3 7
Indexed Indirect ADC ($zz,X) $61 2 7
Indirect, Index ADC ($zz),Y $71 2 7

AND - AND Accumulator with Memory

N V T D I Z C
 ? 0  ?
Addressing Mode Syntax Opcode Bytes Cycles
Immediate AND #$ii $29 2 2
Zero Page AND $zz $25 2 4
Zero Page, X AND $zz,X $35 2 4
Absolute AND $aaaa $2d 3 5
Absolute, X AND $aaaa,X $3d 3 5
Absolute, Y AND $aaaa,Y $39 3 5
Indirect AND ($zzzz) $32 3 7
Indexed Indirect AND ($zz,X) $21 2 7
Indirect, Index AND ($zz),Y $31 2 7

ASL - Arithmetic Shift Left

N V T D I Z C
 ? 0  ?  ?

Shifts the value at the location specified by the operand left by one bit, shifting in 0 to Bit0, and writes the result back to that location. Bit7 of the value before the shift is copied to the Carry flag.

Addressing Mode Syntax Opcode Bytes Cycles
Accumulator ASL A $0a 1 2
Zero Page ASL $zz $06 2 6
Zero Page, X ASL $zz,X $16 2 6
Absolute ASL $aaaa $0e 3 7
Absolute, X ASL $aaaa,X $1e 3 7


BBRn - Branch on Bit Reset n

N V T D I Z C
0

If Bit 'n' of the value at the effective address specified by the second operand is clear, branch to the address calculated from the second operand. The second operand is treated as an 8-bit signed number, -128 to 127. When calculating the branch address, the 8-bit signed second operand is added to the address of the byte immediately following the branch instruction. For example, a branch instruction with an operand of $00 will never branch.

256-byte and 8192-byte page-boundary crossing do not incur cycle penalties, unlike other 6502-based processors(or, depending on how the HuC6280 is engineered internally, ALL branches occur a 1-cycle page-crossing penalty on the HuC6280, regardless of page crossing or not).

Addressing Mode Syntax Opcode Bytes Cycles
Zero Page, Relative BBR0 $zz, $rr $0f 3 6*
Zero Page, Relative BBR1 $zz, $rr $1f 3 6*
Zero Page, Relative BBR2 $zz, $rr $2f 3 6*
Zero Page, Relative BBR3 $zz, $rr $3f 3 6*
Zero Page, Relative BBR4 $zz, $rr $4f 3 6*
Zero Page, Relative BBR5 $zz, $rr $5f 3 6*
Zero Page, Relative BBR6 $zz, $rr $6f 3 6*
Zero Page, Relative BBR7 $zz, $rr $7f 3 6*
* Add 2 extra cycles if branch is taken.


BBSn - Branch on Bit Set n

N V T D I Z C
0

If Bit 'n' of the value at the effective address specified by the operand is set, branch to the address calculated from the second operand. The second operand is treated as an 8-bit signed number, -128 to 127. When calculating the branch address, the 8-bit signed second operand is added to the address of the byte immediately following the branch instruction. For example, a branch instruction with an operand of $00 will never branch.

256-byte and 8192-byte page-boundary crossing do not incur cycle penalties, unlike other 6502-based processors(or, depending on how the HuC6280 is engineered internally, ALL branches occur a 1-cycle page-crossing penalty on the HuC6280, regardless of page crossing or not).

Addressing Mode Syntax Opcode Bytes Cycles
Zero Page, Relative BBS0 $zz, $rr $8f 3 6*
Zero Page, Relative BBS1 $zz, $rr $9f 3 6*
Zero Page, Relative BBS2 $zz, $rr $af 3 6*
Zero Page, Relative BBS3 $zz, $rr $bf 3 6*
Zero Page, Relative BBS4 $zz, $rr $cf 3 6*
Zero Page, Relative BBS5 $zz, $rr $df 3 6*
Zero Page, Relative BBS6 $zz, $rr $ef 3 6*
Zero Page, Relative BBS7 $zz, $rr $ff 3 6*

* Add 2 extra cycles if branch is taken.


BCC - Branch on Carry Clear

N V T D I Z C
0

If the carry flag is clear, branch to the address calculated from the operand. The operand is treated as an 8-bit signed number, -128 to 127. When calculating the branch address, the 8-bit signed operand is added to the address of the byte immediately following the branch instruction. For example, a branch instruction with an operand of $00 will never branch.

256-byte and 8192-byte page-boundary crossing do not incur cycle penalties, unlike other 6502-based processors(or, depending on how the HuC6280 is engineered internally, ALL branches occur a 1-cycle page-crossing penalty on the HuC6280, regardless of page crossing or not).

Addressing Mode Syntax Opcode Bytes Cycles
Relative BCC $rr $90 2 2(4 if branch taken)


BCS - Branch on Carry Set

N V T D I Z C
0

If the carry flag is set, branch to the address calculated from the operand. The operand is treated as an 8-bit signed number, -128 to 127. When calculating the branch address, the 8-bit signed operand is added to the address of the byte immediately following the branch instruction. For example, a branch instruction with an operand of $00 will never branch.

256-byte and 8192-byte page-boundary crossing do not incur cycle penalties, unlike other 6502-based processors(or, depending on how the HuC6280 is engineered internally, ALL branches occur a 1-cycle page-crossing penalty on the HuC6280, regardless of page crossing or not).

Addressing Mode Syntax Opcode Bytes Cycles
Relative BCS $rr $b0 2 2(4 if branch taken)


BEQ - Branch on Equal(Zero Set)

N V T D I Z C
0

If the zero flag is set, branch to the address calculated from the operand. The operand is treated as an 8-bit signed number, -128 to 127. When calculating the branch address, the 8-bit signed operand is added to the address of the byte immediately following the branch instruction. For example, a branch instruction with an operand of $00 will never branch.

256-byte and 8192-byte page-boundary crossing do not incur cycle penalties, unlike other 6502-based processors(or, depending on how the HuC6280 is engineered internally, ALL branches occur a 1-cycle page-crossing penalty on the HuC6280, regardless of page crossing or not).

Addressing Mode Syntax Opcode Bytes Cycles
Relative BEQ $rr $f0 2 2(4 if branch taken)


BIT - Test Memory Bits with Accumulator

N V T D I Z C
 ?  ? 0  ?
Addressing Mode Syntax Opcode Bytes Cycles
Immediate BIT #$ii $89 2 2
Zero Page BIT $zz $24 2 4
Zero Page, X BIT $zz,X $34 2 4
Absolute BIT $aaaa $2c 3 5
Absolute, X BIT $aaaa,X $3c 3 5


BMI - Branch on Minus(Negative Set)

N V T D I Z C
0

If the negative flag is set, branch to the address calculated from the operand. The operand is treated as an 8-bit signed number, -128 to 127. When calculating the branch address, the 8-bit signed operand is added to the address of the byte immediately following the branch instruction. For example, a branch instruction with an operand of $00 will never branch.

256-byte and 8192-byte page-boundary crossing do not incur cycle penalties, unlike other 6502-based processors(or, depending on how the HuC6280 is engineered internally, ALL branches occur a 1-cycle page-crossing penalty on the HuC6280, regardless of page crossing or not).

Addressing Mode Syntax Opcode Bytes Cycles
Relative BMI $rr $30 2 2(4 if branch taken)


BNE - Branch on Not Equal(Zero Clear)

N V T D I Z C
0

If the zero flag is clear, branch to the address calculated from the operand. The operand is treated as an 8-bit signed number, -128 to 127. When calculating the branch address, the 8-bit signed operand is added to the address of the byte immediately following the branch instruction. For example, a branch instruction with an operand of $00 will never branch.

256-byte and 8192-byte page-boundary crossing do not incur cycle penalties, unlike other 6502-based processors(or, depending on how the HuC6280 is engineered internally, ALL branches occur a 1-cycle page-crossing penalty on the HuC6280, regardless of page crossing or not).

Addressing Mode Syntax Opcode Bytes Cycles
Relative BNE $rr $d0 2 2(4 if branch taken)


BPL - Branch on Plus(Negative Clear)

N V T D I Z C
0

If the negative flag is clear, branch to the address calculated from the operand. The operand is treated as an 8-bit signed number, -128 to 127. When calculating the branch address, the 8-bit signed operand is added to the address of the byte immediately following the branch instruction. For example, a branch instruction with an operand of $00 will never branch.

256-byte and 8192-byte page-boundary crossing do not incur cycle penalties, unlike other 6502-based processors(or, depending on how the HuC6280 is engineered internally, ALL branches occur a 1-cycle page-crossing penalty on the HuC6280, regardless of page crossing or not).

Addressing Mode Syntax Opcode Bytes Cycles
Relative BPL $rr $10 2 2(4 if branch taken)


BRA - Branch

N V T D I Z C
0

Unconditionally branch to the address calculated from the operand. The operand is treated as an 8-bit signed number, -128 to 127. When calculating the branch address, the 8-bit signed operand is added to the address of the byte immediately following the branch instruction. For example, a branch instruction with an operand of $00 will never branch.

256-byte and 8192-byte page-boundary crossing do not incur cycle penalties, unlike other 6502-based processors(or, depending on how the HuC6280 is engineered internally, ALL branches occur a 1-cycle page-crossing penalty on the HuC6280, regardless of page crossing or not).

Addressing Mode Syntax Opcode Bytes Cycles
Relative BRA $rr $80 2 4


BRK - Break

N V T D I Z C
0 0 1

Forces a software interrupt using IRQ2's vector. Contrary to IRQs, BRK will push the status flags register with bit 4('B' flag) set.

Addressing Mode Syntax Opcode Bytes Cycles
Implied BRK $00 1 8


BSR - Branch to Subroutine

N V T D I Z C
0
Addressing Mode Syntax Opcode Bytes Cycles
Relative BSR $rr $44 2 8


BVC - Branch on Overflow Clear

N V T D I Z C
0

If the overflow flag is clear, branch to the address calculated from the operand. The operand is treated as an 8-bit signed number, -128 to 127. When calculating the branch address, the 8-bit signed operand is added to the address of the byte immediately following the branch instruction. For example, a branch instruction with an operand of $00 will never branch.

256-byte and 8192-byte page-boundary crossing do not incur cycle penalties, unlike other 6502-based processors(or, depending on how the HuC6280 is engineered internally, ALL branches occur a 1-cycle page-crossing penalty on the HuC6280, regardless of page crossing or not).

Addressing Mode Syntax Opcode Bytes Cycles
Relative BVC $rr $50 2 2


BVS - Branch on Overflow Set

N V T D I Z C
0

If the overflow flag is set, branch to the address calculated from the operand. The operand is treated as an 8-bit signed number, -128 to 127. When calculating the branch address, the 8-bit signed operand is added to the address of the byte immediately following the branch instruction. For example, a branch instruction with an operand of $00 will never branch.

256-byte and 8192-byte page-boundary crossing do not incur cycle penalties, unlike other 6502-based processors(or, depending on how the HuC6280 is engineered internally, ALL branches occur a 1-cycle page-crossing penalty on the HuC6280, regardless of page crossing or not).

Addressing Mode Syntax Opcode Bytes Cycles
Relative BVS $rr $70 2 2


CLA - Clear Accumulator

N V T D I Z C
0

Clears the accumulator(reset to 0).

Addressing Mode Syntax Opcode Bytes Cycles
Implied CLA $62 1 2


CLC - Clear Carry Flag

N V T D I Z C
0 0

Clears the carry flag.

Addressing Mode Syntax Opcode Bytes Cycles
Implied CLC $18 1 2


CLD - Clear Decimal Flag

N V T D I Z C
0 0

Clears the decimal flag, disabling decimal mode.

Addressing Mode Syntax Opcode Bytes Cycles
Implied CLD $d8 1 2


CLI - Clear Interrupt Flag

N V T D I Z C
0 0

Clears the interrupt flag, allowing IRQs to be processed(note that a change in the interrupt flag with SEI/CLI will only prevent/allow interrupts AFTER the next instruction is executed).

Addressing Mode Syntax Opcode Bytes Cycles
Implied CLI $58 1 2


CLV - Clear Overflow Flag

N V T D I Z C
0 0
Addressing Mode Syntax Opcode Bytes Cycles
Implied CLV $b8 1 2


CLX - Clear X

N V T D I Z C
0
Addressing Mode Syntax Opcode Bytes Cycles
Implied CLX $82 1 2


CLY - Clear Y

N V T D I Z C
0
Addressing Mode Syntax Opcode Bytes Cycles
Implied CLY $c2 1 2


CMP - Compare Accumulator with Memory

N V T D I Z C
 ? 0  ?  ?
Addressing Mode Syntax Opcode Bytes Cycles
Immediate CMP #$ii $c9 2 2
Zero Page CMP $zz $c5 2 4
Zero Page, X CMP $zz,X $d5 2 4
Absolute CMP $aaaa $cd 3 5
Absolute, X CMP $aaaa,X $dd 3 5
Absolute, Y CMP $aaaa,Y $d9 3 5
Indirect CMP ($zzzz) $d2 3 7
Indexed Indirect CMP ($zz,X) $c1 2 7
Indirect, Index CMP ($zz),Y $d1 2 7

CPX - Compare X with Memory

N V T D I Z C
 ? 0  ?  ?
Addressing Mode Syntax Opcode Bytes Cycles
Immediate CPX #$ii $e0 2 2
Zero Page CPX $zz $e4 2 4
Absolute CPX $aaaa $ec 3 5


CPY - Compare Y with Memory

N V T D I Z C
 ? 0  ?  ?
Addressing Mode Syntax Opcode Bytes Cycles
Immediate CPY #$ii $c0 2 2
Zero Page CPY $zz $c4 2 4
Absolute CPY $aaaa $cc 3 5


CSH - Change Speed High

N V T D I Z C
0
Addressing Mode Syntax Opcode Bytes Cycles
Implied CSH $d4 1 3


CSL - Change Speed Low

N V T D I Z C
0
Addressing Mode Syntax Opcode Bytes Cycles
Implied CSL $54 1 3


DEC - Decrement

N V T D I Z C
 ? 0  ?
Addressing Mode Syntax Opcode Bytes Cycles
Zero Page DEC $zz $c6 2 6
Zero Page, X DEC $zz,X $d6 2 6
Absolute DEC $aaaa $ce 3 7
Absolute, X DEC $aaaa,X $de 3 7


DEX - Decrement X

N V T D I Z C
 ? 0  ?
Addressing Mode Syntax Opcode Bytes Cycles
Implied DEX $ca 1 2


DEY - Decrement Y

N V T D I Z C
 ? 0  ?
Addressing Mode Syntax Opcode Bytes Cycles
Implied DEY $88 1 2


EOR - Exclusive OR Accumulator with Memory

N V T D I Z C
 ? 0  ?

Logically XOR the value referenced by the operand to the accumulator.

Addressing Mode Syntax Opcode Bytes Cycles
Immediate EOR #$ii $49 2 2
Zero Page EOR $zz $45 2 4
Zero Page, X EOR $zz,X $55 2 4
Absolute EOR $aaaa $4d 3 5
Absolute, X EOR $aaaa,X $5d 3 5
Absolute, Y EOR $aaaa,Y $59 3 5
Indirect EOR ($zzzz) $52 3 7
Indexed Indirect EOR ($zz,X) $41 2 7
Indirect, Index EOR ($zz),Y $51 2 7

INC - Increment

N V T D I Z C
 ? 0  ?

Increments the value of the location specified by the operand by one. The Carry flag is not used, nor is it modified.

Addressing Mode Syntax Opcode Bytes Cycles
Accumulator INC A $1a 1 2
Zero Page INC $zz $e6 2 6
Zero Page, X INC $zz,X $f6 2 6
Absolute INC $aaaa $ee 3 7
Absolute, X INC $aaaa,X $fe 3 7


INX - Increment X

N V T D I Z C
 ? 0  ?

Increments the value in the X register by one. The Carry flag is not used, nor is it modified.

Addressing Mode Syntax Opcode Bytes Cycles
Implied INX $e8 1 2


INY - Increment Y

N V T D I Z C
 ? 0  ?

Increments the value in the Y register by one. The Carry flag is not used, nor is it modified.

Addressing Mode Syntax Opcode Bytes Cycles
Implied INY $c8 1 2


JMP - Jump

N V T D I Z C
0

Transfers control(sets the program counter) to the effective address calculated from the operand.

Addressing Mode Syntax Opcode Bytes Cycles
Absolute JMP $aaaa $4c 3 4
Indirect JMP ($zzzz) $6c 3 7
Indexed Indirect JMP ($zzzz,X) $7c 3 7

JSR - Jump to Subroutine

N V T D I Z C
0
Addressing Mode Syntax Opcode Bytes Cycles
Absolute JSR $aaaa $20 3 7


LDA - Load Accumulator

N V T D I Z C
 ? 0  ?

Loads the accumulator with the value at the effective address.

Addressing Mode Syntax Opcode Bytes Cycles
Immediate LDA #$ii $a9 2 2
Zero Page LDA $zz $a5 2 4
Zero Page, X LDA $zz,X $b5 2 4
Absolute LDA $aaaa $ad 3 5
Absolute, X LDA $aaaa,X $bd 3 5
Absolute, Y LDA $aaaa,Y $b9 3 5
Indirect LDA ($zzzz) $b2 3 7
Indexed Indirect LDA ($zz,X) $a1 2 7
Indirect, Index LDA ($zz),Y $b1 2 7

LDX - Load X

N V T D I Z C
 ? 0  ?

Loads the X register with the value at the effective address.

Addressing Mode Syntax Opcode Bytes Cycles
Immediate LDX #$ii $a2 2 2
Zero Page LDX $zz $a6 2 4
Zero Page, Y LDX $zz,Y $b6 2 4
Absolute LDX $aaaa $ae 3 5
Absolute, Y LDX $aaaa,Y $be 3 5


LDY - Load Y

N V T D I Z C
 ? 0  ?

Loads the Y register with the value at the effective address.

Addressing Mode Syntax Opcode Bytes Cycles
Immediate LDY #$ii $a0 2 2
Zero Page LDY $zz $a4 2 4
Zero Page, X LDY $zz,X $b4 2 4
Absolute LDY $aaaa $ac 3 5
Absolute, X LDY $aaaa,X $bc 3 5


LSR - Logical Shift Right

N V T D I Z C
 ? 0  ? 0
Addressing Mode Syntax Opcode Bytes Cycles
Accumulator LSR A $4a 1 2
Zero Page LSR $zz $46 2 6
Zero Page, X LSR $zz,X $56 2 6
Absolute LSR $aaaa $4e 3 7
Absolute, X LSR $aaaa,X $5e 3 7


NOP - No Operation

N V T D I Z C
0
Addressing Mode Syntax Opcode Bytes Cycles
Implied NOP $ea 1 2


ORA - OR Accumulator with Memory

N V T D I Z C
 ? 0  ?

Logically OR the value referenced by the operand with the accumulator, storing the result in the accumulator.

Addressing Mode Syntax Opcode Bytes Cycles
Immediate ORA #$ii $09 2 2
Zero Page ORA $zz $05 2 4
Zero Page, X ORA $zz,X $15 2 4
Absolute ORA $aaaa $0d 3 5
Absolute, X ORA $aaaa,X $1d 3 5
Absolute, Y ORA $aaaa,Y $19 3 5
Indirect ORA ($zzzz) $12 3 7
Indexed Indirect ORA ($zz,X) $01 2 7
Indirect, Index ORA ($zz),Y $11 2 7

PHA - Push A

N V T D I Z C
0

Pushes the accumulator to the stack.

Addressing Mode Syntax Opcode Bytes Cycles
Implied PHA $48 1 3


PHP - Push P

N V T D I Z C
0

Pushes the status flags(1 byte) to the stack.

Addressing Mode Syntax Opcode Bytes Cycles
Implied PHP $08 1 3


PHX - Push X

N V T D I Z C
0

Pushes the X register to the stack.

Addressing Mode Syntax Opcode Bytes Cycles
Implied PHX $da 1 3


PHY - Push Y

N V T D I Z C
0

Pushes the Y register to the stack.

Addressing Mode Syntax Opcode Bytes Cycles
Implied PHY $5a 1 3


PLA - Pull A

N V T D I Z C
 ? 0  ?

Pulls a value off the stack, and stores the value in the accumulator.

Addressing Mode Syntax Opcode Bytes Cycles
Implied PLA $68 1 4


PLP - Pull P

N V T D I Z C
 ?  ?  ?  ?  ?  ?  ?
Addressing Mode Syntax Opcode Bytes Cycles
Implied PLP $28 1 4


PLX - Pull X

N V T D I Z C
 ? 0  ?

Pulls a value off the stack, and stores the value in the X register.

Addressing Mode Syntax Opcode Bytes Cycles
Implied PLX $fa 1 4


PLY - Pull Y

N V T D I Z C
 ? 0  ?

Pulls a value off the stack, and stores the value in Y register.

Addressing Mode Syntax Opcode Bytes Cycles
Implied PLY $7a 1 4


RMBn - Reset Memory Bit n

N V T D I Z C
0

Reads the zero-page address specified by the operand, resets(clears) the bit "n", and then writes it back to the aforementioned address.

Addressing Mode Syntax Opcode Bytes Cycles
Zero Page RMB0 $zz $07 2 7
Zero Page RMB1 $zz $17 2 7
Zero Page RMB2 $zz $27 2 7
Zero Page RMB3 $zz $37 2 7
Zero Page RMB4 $zz $47 2 7
Zero Page RMB5 $zz $57 2 7
Zero Page RMB6 $zz $67 2 7
Zero Page RMB7 $zz $77 2 7


ROL - Rotate Left

N V T D I Z C
 ? 0  ?  ?
Addressing Mode Syntax Opcode Bytes Cycles
Accumulator ROL A $2a 1 2
Zero Page ROL $zz $26 2 6
Zero Page, X ROL $zz,X $36 2 6
Absolute ROL $aaaa $2e 3 7
Absolute, X ROL $aaaa,X $3e 3 7


ROR - Rotate Right

N V T D I Z C
 ? 0  ?  ?
Addressing Mode Syntax Opcode Bytes Cycles
Accumulator ROR A $6a 1 2
Zero Page ROR $zz $66 2 6
Zero Page, X ROR $zz,X $76 2 6
Absolute ROR $aaaa $6e 3 7
Absolute, X ROR $aaaa,X $7e 3 7


RTI - Return from Interrupt

N V T D I Z C
 ?  ?  ?  ?  ?  ?  ?
Addressing Mode Syntax Opcode Bytes Cycles
Implied RTI $40 1 7


RTS - Return from Subroutine

N V T D I Z C
0
Addressing Mode Syntax Opcode Bytes Cycles
Implied RTS $60 1 7


SAX - Swap A and X

N V T D I Z C
0

Swaps the values in the accumulator and X register.

Addressing Mode Syntax Opcode Bytes Cycles
Implied SAX $22 1 3


SAY - Swap A and Y

N V T D I Z C
0

Swap the values in the accumulator and Y register.

Addressing Mode Syntax Opcode Bytes Cycles
Implied SAY $42 1 3


SBC - Subtract with Borrow

N V T D I Z C
 ?  ? 0  ?  ?

If the Decimal-mode CPU flag is set, an extra cycle will be taken(*confirmed with Immediate mode only, however, other addressing modes need to be tested, but should yield the same result).

The overflow flag is not affected by this instruction if in Decimal mode.

Addressing Mode Syntax Opcode Bytes Cycles
Immediate SBC #$ii $e9 2 2
Zero Page SBC $zz $e5 2 4
Zero Page, X SBC $zz,X $f5 2 4
Absolute SBC $aaaa $ed 3 5
Absolute, X SBC $aaaa,X $fd 3 5
Absolute, Y SBC $aaaa,Y $f9 3 5
Indirect SBC ($zzzz) $f2 3 7
Indexed Indirect SBC ($zz,X) $e1 2 7
Indirect, Index SBC ($zz),Y $f1 2 7

SEC - Set Carry Flag

N V T D I Z C
0 1

Sets the carry flag.

Addressing Mode Syntax Opcode Bytes Cycles
Implied SEC $38 1 2


SED - Set Decimal Flag

N V T D I Z C
0 1

Sets the decimal flag, enabling decimal mode.

Addressing Mode Syntax Opcode Bytes Cycles
Implied SED $f8 1 2


SEI - Set Interrupt Flag

N V T D I Z C
0 1

Sets the interrupt flag, preventing IRQs from being processed(note that a change in the interrupt flag with SEI/CLI will only prevent/allow interrupts AFTER the next instruction is executed).

Addressing Mode Syntax Opcode Bytes Cycles
Implied SEI $78 1 2


SET - Set T Flag

N V T D I Z C
1

Sets the T flag, which changes the behavior of the next instruction if the next instruction is ADC, AND, EOR, ORA, or SBC, in which case the operation is performed on the zero-page address specified by the X register, instead of the accumulator.

Note that interrupt processing preserves the T-flag, and clears the T-flag in the interrupt handler, so a programmer needn't worry about an interrupt occuring between SET and the next instruction.

Addressing Mode Syntax Opcode Bytes Cycles
Implied SET $f4 1 2


SMBn - Set Memory Bit n

N V T D I Z C
0

Reads the zero-page address specified by the operand, sets the bit "n", and then writes it back to the aforementioned address.

Addressing Mode Syntax Opcode Bytes Cycles
Zero Page SMB0 $zz $87 2 7
Zero Page SMB1 $zz $97 2 7
Zero Page SMB2 $zz $a7 2 7
Zero Page SMB3 $zz $b7 2 7
Zero Page SMB4 $zz $c7 2 7
Zero Page SMB5 $zz $d7 2 7
Zero Page SMB6 $zz $e7 2 7
Zero Page SMB7 $zz $f7 2 7


ST0 - Store (HuC6270) VDC No. 0

N V T D I Z C
0

Writes the immediate value to the physical address $1FE000, the (HuC6270) VDC's address register.

Addressing Mode Syntax Opcode Bytes Cycles
Immediate ST0 #$ii $03 2 5


ST1 - Store (HuC6270) VDC No. 1

N V T D I Z C
0

Writes the immediate value to the physical address $1FE002, the (HuC6270) VDC's lower data register.

Addressing Mode Syntax Opcode Bytes Cycles
Immediate ST1 #$ii $13 2 5


ST2 - Store (HuC6270) VDC No. 2

N V T D I Z C
0

Writes the immediate value to the physical address $1FE003, the (HuC6270) VDC's upper data register.

Addressing Mode Syntax Opcode Bytes Cycles
Immediate ST2 #$ii $23 2 5


STA - Store Accumulator

N V T D I Z C
0

Stores the value in the accumulator to the effective address specified by the operand.

Addressing Mode Syntax Opcode Bytes Cycles
Zero Page STA $zz $85 2 4
Zero Page, X STA $zz,X $95 2 4
Absolute STA $aaaa $8d 3 5
Absolute, X STA $aaaa,X $9d 3 5
Absolute, Y STA $aaaa,Y $99 3 5
Indirect STA ($zzzz) $92 3 7
Indexed Indirect STA ($zz,X) $81 2 7
Indirect, Index STA ($zz),Y $91 2 7

STX - Store X

N V T D I Z C
0

Stores the value in the X register to the effective address specified by the operand.

Addressing Mode Syntax Opcode Bytes Cycles
Zero Page STX $zz $86 2 4
Zero Page, Y STX $zz,Y $96 2 4
Absolute STX $aaaa $8e 3 5


STY - Store Y

N V T D I Z C
0

Stores the value in the Y register to the effective address specified by the operand.

Addressing Mode Syntax Opcode Bytes Cycles
Zero Page STY $zz $84 2 4
Zero Page, X STY $zz,X $94 2 4
Absolute STY $aaaa $8c 3 5


STZ - Store Zero

N V T D I Z C
0

Stores zero to the effective address specified by the operand.

Addressing Mode Syntax Opcode Bytes Cycles
Zero Page STZ $zz $64 2 4
Zero Page, X STZ $zz,X $74 2 4
Absolute STZ $aaaa $9c 3 5
Absolute, X STZ $aaaa,X $9e 3 5


SXY - Swap X and Y

N V T D I Z C
0

Swaps the values in the X register and the Y register.

Addressing Mode Syntax Opcode Bytes Cycles
Implied SXY $02 1 3


TAI - Transfer Alternate Increment

N V T D I Z C
0

Enters block memory transfer sequence shown by this pseudocode('ssss' is the 16-bit source address, 'dddd' is the 16-bit destination address, and 'llll' is the 16-bit length counter, in bytes):

Alternate = 0
Do
 Value = Read(ssss + Alternate)
 Write(dddd, value)
 dddd = dddd + 1
 llll = llll - 1
 Alternate = Alternate ^ 1
While llll != 0

It is important to note that the comparison of the length counter to 0 is done AFTER the length counter is decremented, not before, so a length of "0" will be effectively treated as a length of "65536".

Please note that the cycles-per-byte-transferred will be higher if (HuC6270) VDC registers are used as source and/or destination.

All block-transfer instructions push Y, A, X in that order before beginning the block transfer, and pop X, A, Y in that order after the transfer is complete.

Addressing Mode Syntax Opcode Bytes Cycles
Block Transfer TAI $ssss, $dddd, $llll $f3 7 17 + 6 * llll


TAM - Transfer Accumulator to MPRs

N V T D I Z C
0

Copies the value in the accumulator to each MPR with the corresponding bit set in the immediate operand, eg. TAM #$41 will load MPR0 and MPR6 with the value in the accumulator. If no bits are set, no transfer will occur, and the instruction is effectively a 5-cycle NOP.

Addressing Mode Syntax Opcode Bytes Cycles
Immediate TAM #$ii $53 2 5


TAX - Transfer Accumulator to X

N V T D I Z C
 ? 0  ?

Copies the value of the accumulator to the X register.

Addressing Mode Syntax Opcode Bytes Cycles
Implied TAX $aa 1 2


TAY - Transfer Accumulator to Y

N V T D I Z C
 ? 0  ?

Copies the value of the accumulator to the Y register.

Addressing Mode Syntax Opcode Bytes Cycles
Implied TAY $a8 1 2


TDD - Transfer Decrement Decrement

N V T D I Z C
0

Enters block memory transfer sequence shown by this pseudocode('ssss' is the 16-bit source address, 'dddd' is the 16-bit destination address, and 'llll' is the 16-bit length counter, in bytes):

Do
 Value = Read(ssss)
 Write(dddd, value)
 ssss = ssss - 1
 dddd = dddd - 1
 llll = llll - 1
While llll != 0

It is important to note that the comparison of the length counter to 0 is done AFTER the length counter is decremented, not before, so a length of "0" will be effectively treated as a length of "65536".

Please note that the cycles-per-byte-transferred will be higher if (HuC6270) VDC registers are used as source and/or destination.

All block-transfer instructions push Y, A, X in that order before beginning the block transfer, and pop X, A, Y in that order after the transfer is complete.

Addressing Mode Syntax Opcode Bytes Cycles
Block Transfer TDD $ssss, $dddd, $llll $c3 7 17 + 6 * llll


TIA - Transfer Increment Alternate

N V T D I Z C
0


Enters block memory transfer sequence shown by this pseudocode('ssss' is the 16-bit source address, 'dddd' is the 16-bit destination address, and 'llll' is the 16-bit length counter, in bytes):

Alternate = 0
Do
 Value = Read(ssss)
 Write(dddd + Alternate, Value)
 ssss = ssss + 1
 llll = llll - 1
 Alternate = Alternate ^ 1
While llll != 0

It is important to note that the comparison of the length counter to 0 is done AFTER the length counter is decremented, not before, so a length of "0" will be effectively treated as a length of "65536".

All block-transfer instructions push Y, A, X in that order before beginning the block transfer, and pop X, A, Y in that order after the transfer is complete.

Please note that the cycles-per-byte-transferred will be higher if (HuC6270) VDC registers are used as source and/or destination.

Addressing Mode Syntax Opcode Bytes Cycles
Block Transfer TIA $ssss, $dddd, $llll $e3 7 17 + 6 * llll


TII - Transfer Increment Increment

N V T D I Z C
0

Enters block memory transfer sequence shown by this pseudocode('ssss' is the 16-bit source address, 'dddd' is the 16-bit destination address, and 'llll' is the 16-bit length counter, in bytes):

Do
 Value = Read(ssss)
 Write(dddd, Value)
 ssss = ssss + 1
 dddd = dddd + 1
 llll = llll - 1
While llll != 0

It is important to note that the comparison of the length counter to 0 is done AFTER the length counter is decremented, not before, so a length of "0" will be effectively treated as a length of "65536".

All block-transfer instructions push Y, A, X in that order before beginning the block transfer, and pop X, A, Y in that order after the transfer is complete.

Please note that the cycles-per-byte-transferred will be higher if (HuC6270) VDC registers are used as source and/or destination.

Addressing Mode Syntax Opcode Bytes Cycles
Block Transfer TII $ssss, $dddd, $llll $73 7 17 + 6 * llll


TIN - Transfer Increment

N V T D I Z C
0

Enters block memory transfer sequence shown by this pseudocode('ssss' is the 16-bit source address, 'dddd' is the 16-bit destination address, and 'llll' is the 16-bit length counter, in bytes):

Do
 Value = Read(ssss)
 Write(dddd, value)
 ssss = ssss + 1
 llll = llll - 1
While llll != 0

It is important to note that the comparison of the length counter to 0 is done AFTER the length counter is decremented, not before, so a length of "0" will be effectively treated as a length of "65536".

All block-transfer instructions push Y, A, X in that order before beginning the block transfer, and pop X, A, Y in that order after the transfer is complete.

Please note that the cycles-per-byte-transferred will be higher if (HuC6270) VDC registers are used as source and/or destination.

Addressing Mode Syntax Opcode Bytes Cycles
Block Transfer TIN $ssss, $dddd, $llll $d3 7 17 + 6 * llll


TMA - Transfer MPR to Accumulator

N V T D I Z C
0

Copies the value in the MPR, specified by the corresponding bit being set in the immediate operand, to the accumulator. If an immediate value of $00 is used, the accumulator will be loaded with the last value transfered by TAM(note that if an immediate value of $00 is used with TAM, no transfer occurs, and as such won't be read back if an immediate value of $00 is used with TMA). Undefined behavior results if multiple bits are set.

Addressing Mode Syntax Opcode Bytes Cycles
Immediate TMA #$ii $43 2 4


TRB - Test and Reset Bits against Accumulator

N V T D I Z C
 ?  ? 0  ?

Loads the value specified by the effective address of the operand, clears all bits whose corresponding bits are set in the accumulator(result = value & ~accumulator), and stores the result to the aforementioned address.

The zero flag is set according to the result. The N and V flags are copied from bit7 and bit6 of the value loaded from the effective address, before it is operated on.

Addressing Mode Syntax Opcode Bytes Cycles
Zero Page TRB $zz $14 2 6
Absolute TRB $aaaa $1c 3 7


TSB - Test and Set Bits against Accumulator

N V T D I Z C
 ?  ? 0  ?

Loads the value specified by the effective address of the operand, sets all bits whose corresponding bits are set in the accumulator(result = value & ~accumulator), and stores the result to the aforementioned address.

The zero flag is set according to the result. The N and V flags are copied from bit7 and bit6 of the value loaded from the effective address, before it is operated on.

Addressing Mode Syntax Opcode Bytes Cycles
Zero Page TSB $zz $04 2 6
Absolute TSB $aaaa $0c 3 7


TST - Test

N V T D I Z C
 ?  ? 0  ?

The N and V flags are copied from bit7 and bit6 of the value loaded from the effective address(they are *not* set as the result of the AND operation used to determine the Z flag's state).

The Z flag is determined according to the result of logically AND'ing the immediate value and the value at the effective address.

Addressing Mode Syntax Opcode Bytes Cycles
Immediate, Zero Page TST #$ii, $zz $83 3 7
Immediate, Zero Page, X TST #$ii, $zz, X $a3 3 7
Immediate, Absolute TST #$ii, $aaaa $93 4 8
Immediate, Absolute, X TST #$ii, $aaaa, X $b3 4 8


TSX - Transfer Stack Pointer to X

N V T D I Z C
 ? 0  ?
Addressing Mode Syntax Opcode Bytes Cycles
Implied TSX $ba 1 2


TXA - Transfer X to A

N V T D I Z C
 ? 0  ?

Copies the value in the X register to the Accumulator.

Addressing Mode Syntax Opcode Bytes Cycles
Implied TXA $8a 1 2


TXS - Track X to Stack Pointer

N V T D I Z C
0

Copies the value in X to the stack pointer.

Addressing Mode Syntax Opcode Bytes Cycles
Implied TXS $9a 1 2


TYA - Transfer Y to Accumulator

N V T D I Z C
 ? 0  ?

Copies the value in Y to the Accumulator.

Addressing Mode Syntax Opcode Bytes Cycles
Implied TYA $98 1 2