ACME

         ...the ACME Crossassembler for Multiple Environments

                          --- cpu types ---


ACME supports the following cpu types:



***   6502

This is the instruction set of the original NMOS 6502 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.



***   6510

This is the 6502 variant used in the C64 computer. It uses the same
instruction set as the 6502, but in addition to that, ACME supports
most of the undocumented opcodes as well.
See "docs/Illegals.txt" for more info.



***   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.



***   r65c02

This is a superset of 65c02, probably originally by Rockwell. It adds
bit manipulation instructions:
	BBR0 $12, near_target	branch on bit reset in zp
	BBS0 $12, near_target	branch on bit set in zp
	RMB0 $12		reset memory bit in zp
	SMB0 $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.



***   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.



***   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.



***   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.



***   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.



***   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 of the undocumented opcodes.