122 lines
2.7 KiB
Markdown
122 lines
2.7 KiB
Markdown
6502 Opcodes
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============
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<!--
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Copyright (c) 2014-2024, Chris Pressey, Cat's Eye Technologies.
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This file is distributed under a 2-clause BSD license. See LICENSES/ dir.
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SPDX-License-Identifier: LicenseRef-BSD-2-Clause-X-SixtyPical
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-->
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As used or unused in SixtyPical.
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### ld ###
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ld a, 123 → LDA #123
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ld a, lives → LDA LIVES
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ld x, 123 → LDX #123
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ld x, lives → LDX LIVES
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ld y, 123 → LDY #123
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ld y, lives → LDY LIVES
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ld x, a → TAX
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ld y, a → TAY
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ld a, x → TXA
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ld a, y → TYA
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### st ###
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st a, lives → STA LIVES
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st x, lives → STX LIVES
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st y, lives → STY LIVES
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st on, c → SEC
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st off, c → CLC
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### add dest, src ###
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add a, delta → ADC DELTA
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add a, 1 → ADC #1
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### inc ###
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inc x → INX
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inc y → INY
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inc lives → INC LIVES
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### sub ###
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sub a, delta → SBC DELTA
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sub a, 1 → SBC #1
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### dec ###
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dec x → DEX
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dec y → DEY
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dec lives → DEC LIVES
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### cmp ###
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cmp a, delta → CMP DELTA
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cmp a, 1 → CMP #1
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cmp x, 1 → CPX #1
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cmp y, 1 → CPY #1
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### and, or, xor ###
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and a, 8 → AND #8
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or a, 8 → ORA #8
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xor a, 8 → EOR #8
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### shl, shr ###
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shl <dest-memory-location>
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shr <dest-memory-location>
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shl a → ROL A
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shl lives → ROL LIVES
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shr a → ROR A
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shr lives → ROR LIVES
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### call ###
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call routine → JSR ROUTINE
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### if ###
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if z → BEQ LABEL
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if not z → BNE LABEL
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if n → BMI LABEL
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if not n → BPL LABEL
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if c → BCS LABEL
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if not c → BCC LABEL
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if v → BVS LABEL
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if not v → BVC LABEL
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### 6502 instructions unsupported ###
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ASL Shift Left One Bit (Memory or Accumulator)
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LSR Shift Right One Bit (Memory or Accumulator)
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BIT Test Bits in Memory with Accumulator
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BRK Force Break
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CLD Clear Decimal Mode
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CLI Clear interrupt Disable Bit
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CLV Clear Overflow Flag
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NOP No Operation
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JMP Jump to New Location // but may be generated as part of `if`
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PHA Push Accumulator on Stack
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PHP Push Processor Status on Stack
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PLA Pull Accumulator from Stack
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PLP Pull Processor Status from Stack
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RTI Return from Interrupt
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RTS Return from Subroutine
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SED Set Decimal Mode
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SEI Set Interrupt Disable Status
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TSX Transfer Stack Pointer to Index X
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TXS Transfer Index X to Stack Pointer
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