Date   : Tue, 16 Jan 1996 09:55:37 +0000 (GMT)
From   : jkb@...
Subject: Re: Illegal opcodes

Nigel Barrett wrote:

>I once had a BASIC disassembler which I modified to do all the illegal
>opcodes. Don't ask me to find it, it's long gone, but a new one shouldn't
>take you more than a few hours to knock out.

I've got a 6502 and 65c02 disassembler written in assembly. It's a scrolling
thing, written to use mode 7 (probably "illegaly", so that it wouldn't
work in
shadow modes I'd guess). It doesn't understand the illegal opcodes, but it
does understand the different byte lengths of the NOP opcodes (6502).  It
should be possible to extend (provided you don't add any more than another 60
opcode names), but it's a bit tricky as I lost the program that generated it
binary lookup table (the format is clearly defined).

The source is available freely for anyone who wants it, although it maybe a
bit tricky separating it from the rest of the commands (it's part of a rom).
See "ftp.mrc-lmb.cam.ac.uk/pub/jkb/beeb/hackrom-1.18.tar.Z".

	James

--
James Bonfield (jkb@...              )   Tel: 01223 402499   Fax: 01223
412282
Medical Research Council - Laboratory of Molecular Biology,
Hills Road, Cambridge, CB2 2QH, England.
Also see Staden Package WWW site at http://www.mrc-lmb.cam.ac.uk/pubseq/