

                                 ACME

         ...the ACME Crossassembler for Multiple Environments

                          --- cpu types ---


ACME supports the following cpu types (shown here as a sort of family
tree):

 6502                   standard
 |
 |\_nmos6502 (=6510)    + undocumented opcodes
 |
 |\_c64dtv2             + BRA/SAC/SIR and some (not all!) undocumented
 |
  \_65c02               + BRA/PHX/PHY/PLX/PLY/STZ/TRB/TSB/...
    |
    |\_65816            16 bit regs, 24 bit address space, ...
    |
     \_r65c02           + bit manipulation instructions
       |
       |\_w65c02        + STP/WAI
       |
        \_65ce02        + Z reg, long branches, ...
          |
           \_4502       + MAP/EOM
             |
              \_m65     + 32-bit pointers, 32-bit 'Q' register



	!cpu 6502

This is the official instruction set of the original NMOS 6502 CPU
designed by MOS (later CSG).
There are 151 documented opcodes.
ACME does not use "A" to indicate "accumulator addressing"; just write
the mnemonic without any argument: "LSR" will work, "LSR A" won't.



	!cpu nmos6502

This instruction set includes the undocumented ("illegal") opcodes of
the NMOS 6502.
See "docs/Illegals.txt" for more info.



	!cpu 6510

This is an alias for "nmos6502", because the 6510 cpu (as used in the
C64 computer) is a variant of this type.



	!cpu c64dtv2

This is the cpu in version 2 of the C64DTV. It uses a superset of the
6502 instruction set. Features:
- new instructions:
	BRA near_target		branch always
	SAC #$12		set accumulator mapping
	SIR #$12		set index register mapping
- support for some (but not all!) of the undocumented opcodes.



	!cpu 65c02

This is the CMOS re-design of the 6502. It seems to have also been
available from Rockwell, GTE/CMD and others. Features:
- new instructions:
	BRA near_target		branch always
	PHX/PHY/PLX/PLY		push/pull X/Y register
	STZ $12			store zero in zp
	STZ $12, x		store zero in zp, x-indexed
	STZ $1234		store zero absolute
	STZ $1234, x		store zero absolute, x-indexed
	TRB $12			test and reset bits in zp
	TRB $1234		test and reset bits absolute
	TSB $12			test and set bits in zp
	TSB $1234		test and set bits absolute
- new addressing modes for existing instructions:
	LDA/STA/ADC/SBC ($12)	zp indirect
	AND/ORA/EOR/CMP ($12)	zp indirect
	BIT #$12		immediate
	BIT $12, x		zp, x-indexed
	BIT $1234, x		absolute, x-indexed
	INC			increment accumulator
	DEC			decrement accumulator
	JMP ($1234, x)		x-indexed indirect
- bugfix for flags in decimal mode
- bugfix for JMP($xxff) instruction
- undocumented opcodes are NOPs (although of different lengths)
There are 178 documented opcodes.



	!cpu 65816

This is a superset of 65c02, originally designed by WDC (it seems to
have been available from GTE/CMD as well). Features:
- register sizes can be changed to 16-bit
- 24-bit address space
- several new instructions (including block transfers)
- several new addressing modes for existing instructions
There are 256 documented opcodes, but one of them ("WDM") is reserved
for future expansion.
See "docs/65816.txt" for more info.



	!cpu r65c02

This is a superset of 65c02, probably originally by Rockwell. It adds
bit manipulation instructions:
	BBR4 $12, near_target	branch on bit reset in zp
	BBS5 $12, near_target	branch on bit set in zp
	RMB6 $12		reset memory bit in zp
	SMB7 $12		set memory bit in zp
The digit in the mnemonic is the bit number, therefore it must be in
the 0..7 range.
Chips with this instruction set seem to have been available from
Rockwell, GTE/CMD and others.
There are 210 documented opcodes.



	!cpu w65c02

This is a superset of r65c02, originating at WDC. It adds two new
instructions:
	STP			stop (wait for reset)
	WAI			wait for interrupt
There are 212 documented opcodes.



	!cpu 65ce02

This is a superset of r65c02, originating at CSG. Features:
- Z register
- 16-bit stack pointer
- 16-bit branches
- new instructions (including a few 16-bit operations)
- new addressing modes for existing instructions
There is a known bug: SBC does not work correctly in decimal mode.
There are 256 documented opcodes, but one of them ("AUG") is reserved
for future expansion.
ACME uses different mnemonics for old and new (long) branch
instructions:
	BEQ near_target		old, 8-bit offset
	LBEQ far_target		new, 16-bit offset
The original datasheet called BRA ("branch always") BRU ("branch
unconditional") instead. ACME accepts both mnemonics.



	!cpu 4502

This is basically the same as 65ce02, but
- MAP replaces AUG
- EOM is synonymous to NOP
This cpu core can be found in the CSG4510 chip in the C65.
There are 256 documented opcodes.



	!cpu m65

This is a superset of 4502 specified by the MEGA65 project. It uses
NEG:NEG and NOP as prefix bytes to extend the instruction set.
Features:
- "quad mode" (32-bit data operations on virtual register 'Q')
- "long mode" (32-bit pointer addressing for existing mnemonics)
- "quad" and "long" modes can be combined
quad mode introduces several new mnemonics:
	LDQ/STQ/CPQ		like LDA/STA/CMP
	ADCQ/SBCQ		like ADC/SBC
	ANDQ/EORQ/ORQ		like AND/EOR/ORA
	ASLQ/LSRQ/ROLQ/RORQ	like ASL/LSR/ROL/ROR
	INQ/DEQ			like INC/DEC
	BITQ			like BIT
	ASRQ			like ASR
  The new mnemonics support most of the addressing modes of the
  original mnemonics with these exceptions:
	- there is no immediate addressing
	- indirect-Z-indexed addressing becomes indirect addressing
	- all other indexed addressing modes can only really be used
	with read-modify-write instructions or LDQ, because otherwise
	a part of the 'Q' value would be used as the index.
  CAUTION: The STQ instruction clobbers the N and Z flags!
  There is no "real" Q register, instead A/X/Y/Z are combined to form
  the Q register (A holds lsb, Z holds msb), except for read-modify-
  write instructions, where the 32-bit operation is performed without
  using A/X/Y/Z.
  To load a 32-bit immediate constant into the Q register, use the
  +movq macro from the <m65/std.a> library file.
long mode brings a single new addressing mode for eight mnemonics:
	LDA [$12], z		contents of $12/$13/$14/$15
	STA [$12], z		plus z form the address
	CMP [$12], z
	ADC [$12], z
	SBC [$12], z
	AND [$12], z
	EOR [$12], z
	ORA [$12], z
quad and long modes combined result in another addressing mode for
  eight of the new mnemonics:
	LDQ [$12]		contents of $12/$13/$14/$15
	STQ [$12]		form the address
	CPQ [$12]
	ADCQ [$12]
	SBCQ [$12]
	ANDQ [$12]
	EORQ [$12]
	ORQ [$12]
The NOP mnemonic is disabled for this instruction set because its
opcode is re-used internally as a prefix byte.
CAUTION: The !align pseudo opcode still inserts NOPs.
