In a message dated 31/01/98  22:05:55, you write:

> I was going through a source file and saw this:
>       rep     #$30
>       sep     #$20
>  uh... would there be a point to resetting and setting $20?

It's a habit thing. I do it sometimes. Most SNES apps start of with
clc xce rep $30... it puts the machine into a known state. There is no
difference between rep$30 and rep$10 in this case.


>>It would read 2 when M=1,3 when M=0. ADC is not dependent on X. An
>>instruction such as LDX immediate would depend on X
> doesn't this mean that, if you wrote an assembler routine for a certain 
> mode, it would completely crash if you ran it in any other mode?

Yes.... as a 65816 doesn't have that many unimplemented opcodes it 
usually just wanders off into no-mans land.

>  hmm... well, the book never mentioned it and I've never seen a source 
>  file that used that notation...  Perhaps something like:
>      cpy      #$0010
>  Implies that a 16-bit operand is used?

Yes, I've seen this too. I suspect this is the "standard" assembler. The
freeones (TRASM,X112) don't support this quite as well. I actually prefer
the .w .b as its clearer. There's also a .l for the 24-bit address modes.

>>Not a clue. AFAIK no SNES code uses Emulation mode. There are a few
>>basic things- the vectors are wrong, the Stack pointer is always at 
>>  01xx etc.
>>  really?  Is it even worth emulating then?

No. With a SNES, you could run a 32k program in Page 0 & have access 
to all the hardware. I can't see the point in switching back to a limited
CPU. X=1M=1 is very close but with enough extensions to make it 
worthwhile. The only real use I can see for the mode is as a fast
replacement 6502 when you want to keep old software (There are 65816's
much faster than the SNES's)

>  >When an address is X or Y indexed, this is a 'full' addition.
>  hmmmm...so... if DBR=0 and I:
>      LDX #$10
>      LDA $FFF5,X
>  A=($1.0005)?

Can't remember off hand. I think not, in this case it's forced into 00. I
think
it works for 24 bit addresses. 

Paul Robson (autismuk@aol.com)
>  >  
>  >Any way you like... do some of one, then some of another.
>  just curious, have you done some SPC emulation yet?
>  