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M68000 Instruction Set Summary

Copyright, Lewis Bassett, December 2005


Below is a summary of all the instructions explained in the document Sega Megadrive Programming Basics. This list is not exhausive, and many more different instructions also exist. Details of these can be found in the M68000 Programmer's Reference.

ADD Add source to destination
ADDA Add source to address register
ADDI Add immediate to destination
AND AND source with destination
ANDI AND immediate source with destination
BEQ Branch if equal
BGE Branch if greater than or equal to
BLE Branch if less than or equal to
BNE Branch if not equal
BRA Branch to relative address
BSR Branch to subroutine using relative address
CLR Clear destination
CMP Compate source with destination
CMPI Compare immediate immediate source with destination
DBRA Decrement data register and branch
DIVS Divide (signed) destination by source
DIVU Divide (unsigned) destination by source
EOR Exclusive OR source with destination
EORI Exclusive OR immediate source with destination
JMP Jump to definate address
JSR Jump to suroutine using definate address
LEA Load effective address into an address register
MOVE Move data from source to destination
MOVEM Move multple data from sources to destinations
MOVEQ Move one byte of data quickly
MULS Multiply (signed) destination by source
MULU Multiply (unsigned) destination by source
NEG Make Destination a negative
NOP No Operation
NOT Invert Destination
OR OR source with destination
ORI OR immediate source with destination
RTS Return from subroutine
SUB Sutract source from destination
SUBA Subtract source from address register
SUBI Subtract immediate from destination
TST Test destination for zero or negative


Designed & maintained by Lewis AS Bassett
SEGA, Megadrive, Genesis, Sonic the Hedgehog, etc are all owned by Sega Enterprises Ltd