Re: 65c02 disassembler on IIe

[dempson@actrix.gen.nz (David Empson)]

Michael Spangler <mspangler@gemsi.com> wrote:

> I've been wondering if it possible to fix the disassembler on the IIe
> to show the 65c02 instructions.

I doubt it.  If there had been enough space, Apple would have squeezed
it into the enhanced IIe.  It might have been a tradeoff between
supporting 65C02 disassembly and the mini-assembler, and they chose the
latter.

> I found a IIc rom image, and it seems that the disassembler is close
> to the same, at least it fits in the same addresses in the monitor.

That is surprising.  I would have expected that the IIc disassembler
would take over some extra space, e.g. replacing the tape I/O routines
with more code and/or enlarging the lookup table.

(The IIc also has an extra 16 KB of ROM space in the UniDisk and later
firmware revisions, but it is bank switched, so I expect the
mini-assembler would have to be in the main bank in order to access the
tables used by the disassembler.)

> Most of the code and lookup tables are the same too, except for the format
> 1 section at F962, which is wildly different. Any notion as to why this is
> different? If I could figure out what was going on through here it would
> help too, but the monitor list processing is pretty opaque.

I'll have to look at the firmware listings in the IIe and IIc hardware
references to comment on this.  I don't have time right now.

-- 
David Empson
dempson@actrix.gen.nz