Date   : Fri, 02 Sep 1994 12:12:44 WET DST
From   : Bonfield James <jkb@...>
Subject: Re: Reply to: Re: 6502/65c02 op-codes

D Lodge writes:

>>Did you mean 65SC02? Or did you mean the 65SC02?
>
>huh? Can't I read or summat?

OOps sorry, I meant:

Did you mean 65SC02? Or did you mean the 65C02?
Note the lack of the 'S'.

>>I've now got (thanks Stephen Y.) the Rockwell CMOS data sheets for the 65C02,
>>the 65C102 and the 65C112 chips.
>
>If you're offering I'd love these :)

I'm unsure of where they were obtained from. I'll ask Stephen next time I see
him.

>The problem with disassembles for 6502 is checking frame shifts and data - ATM
>mine assumes any byte that doesn't match to an opcode is an EQUB'd byte - it
>doesn't bother checking for strings... The problem is if you start
>disassembling

Note that not all undefined opcodes are one byte. Some are 2 or 3 bytes long.
However treating them all as one byte for the purpose of disassembly may
provide better protection against spuradic data inserted in code.

Typically it's very hard to know when data is data and when it's assembly. The
only way I can think of is analysing the jumps and branches to spot entry
points. This of course isn't trivial and is frought with problems.

I'll send you my copy of 64doc.

       James