68000 Assembly Info

[Pugsy]

Yes, the movem list is a beast for sure and I doubt it will be of any real use as if you need to use movem instructions you should really be using an assembler.

I wouldn't even attempt to open any of those in word - use a proper text editor that has large file support. I suggest notepad++ because I used that to help create it and it's completely free.

http://notepad-plus-plus.org/

[Helder]

Ok, it was a bit simpler than I hoped.

I think this will suffice, I've optimised it as much as I dare.

http://www.mediafire.com/file/wfd5hc...Sega_Saturn.7z

Thanks Pugsy that list is exactly what I needed, I was going to literally go thru all 65535 possible values and write them all down this has saved me hours of work thanks man.

[JLukas]

Any documentation on what the various STT opcodes like STTr do? The most recent example I've seen was a game using it to change a byte in RAM from $00 to $FF to enable a cheat code.

[Pugsy]

Any documentation on what the various STT opcodes like STTr do? The most recent example I've seen was a game using it to change a byte in RAM from $00 to $FF to enable a cheat code.

I'm assuming you mean STS or STC in SH-2? Not seen STT in SH-2 or 68000.

If you mean STS or STC in SH-2 you should find more info on pages 153-156 of this pdf:-

http://koti.kapsi.fi/~antime/sega/files/h12p0.pdf

[JLukas]

Here's the example in question (from Dragon: The Bruce Lee Story for Genesis)
005876 50F8BBCB st $BBCB.w

The $00 in RAM address $FFBBCB changes to $FF

It's called st in Regen, Gens Tracer calls it STTr.

A Google search didn't turn up any documentation...

[Pugsy]

Ah I see, I've never used them myself but ST is just one of the SCC condition codes which are otherwise vaguely similar to to the branch condition codes. Basically the SCC codes will either write 00 or FF (and nothing else) to a memory address depending on the result of the condition code.

Documentation for SCC:-

Scc Set according to condition cc
Operation: IF cc = 1 THEN [destination] ← 111111112
ELSE [destination] ← 000000002

Syntax: Scc
The 68000's Instruction Set 51

Attributes: Size = byte

Description: The specified condition code is tested. If the condition is true, the
bits at the effective address are all set to one (i.e., $FF). Otherwise,
the bits at the effective address are set to zeros (i.e., $00).

SCC set on carry clear C
SCS set on carry set C
SEQ set on equal Z
SGE set on greater than or equal N.V + N.V
SGT set on greater than N.V.Z + N.V.Z
SHI set on higher than C.Z
SLE set on less than or equal Z + N.V + N.V
SLS set on lower than or same C+Z
SLT set on less than N.V + N.V
SMI set on minus (i.e., negative) N
SNE set on not equal Z
SPL set on plus (i.e., positive) N
SVC set on overflow clear V
SVS set on overflow set V
SF set on false (i.e., set never) 0
ST set on true (i.e., set always) 1

[JLukas]

Awesome, that's exactly the explanation I was searching for, thanks Pugsy!