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ALT1
From SnesLab
| Basic Info | |||||||
|---|---|---|---|---|---|---|---|
| Addressing Mode | Opcode | Length | ROM Speed | RAM Speed | Cache Speed | ||
| Implied (type 2) | 3D | 1 byte | 3 cycles | 3 cycles | 1 cycle | ||
| Flags Affected | ||||||||
|---|---|---|---|---|---|---|---|---|
| B | ALT1 | ALT2 | O/V | S | CY | Z | ||
| . | 1 | . | . | . | . | . | ||
ALT1 is both the name of a Super FX flag and the flag prefix instruction that sets it. It is bit 8 of the status flag register.
Syntax
ALT1
The following instructions require ALT1:
- ADC Rn
- BIC Rn
- CMODE
- DIV2
- GETBH
- LDB (Rm)
- LJMP
- LM Rn, (xx)
- LMS Rn, (yy)
- LMULT
- RPIX
- SBC Rn
- STB (Rm)
- UMULT Rn
- XOR Rn
Many instructions clear the ALT1 flag, including:
- ADC Rn
- ADC #n
- ADD Rn
- ADD #n
- AND Rn
- AND #n
- ASR
- BIC Rn
- BIC #n
- CACHE
- CMODE
- CMP Rn
- COLOR
- DEC Rn
- DIV2
- FMULT
- GETB
- GETBH
- GETBL
- GETBS
- GETC
- HIB
- IBT Rn, #pp
- INC Rn
- IWT Rn, #xx
- JMP Rn
- LDB (Rm)
- LDW (Rm)
- LEA Rn, xx
- LINK #n
- LJMP Rn
- LM Rn, (xx)
- LMS Rn, (yy)
- LMULT
- LOB
- LOOP
- LSR
- MERGE
- MOVE Rn, Rn'
- MOVES Rn, Rn'
- MULT Rn
- MULT #n
- NOP
- NOT
- OR Rn
- OR #n
- PLOT
- RAMB
- ROL
- ROMB
- ROR
- RPIX
- SBC Rn
- SBK
- SEX
- SM (xx), Rn
- SMS (yy), Rn
- STB (Rm)
- STOP
- STW (Rm)
- SUB Rn
- SUB #n
- SWAP
- UMULT Rn
- and presumably UMULT #n and XOR too
See Also
External Links
- Official Nintendo documentation on ALT1: 9.8 on page 2-9-7 of Book II
- Table 2-4-2 on page 2-4-4, lbid.
- https://en.wikibooks.org/wiki/Super_NES_Programming/Super_FX_tutorial#Instruction_Set_Table