Re: Zork on the PET at last!

From: Ethan Dicks (
Date: 2002-10-01 07:08:48

> Congratulations!  I remember Zork only available for the Apple, TRS-80
> and Atari and all the nice write ups in BYTE.  Though even after I got
> it on the 64, I never got past that blocked mine tunnel.

I happen to have an original Zork for the TRS-80, as published by
Personal Software on behalf of Infocom.  Love to get a real Model-1
to read it, just to see what version it is.
> BTW 4.0 PETs do some nasty things to cassette buffer #2, don't believe
> it will stay just as you leave it..

Agreed.  I know the 80-col editor ROM does some funny stuff that
doesn't happen with the older ROMs.  I'm also now running into
some 40/80 column wrap-around wierdness under VICE 1.10.  I'll
have to do some regression testing with the older version to see
if it's a real bug or not.  I remember being able to play several
turns under VICE 1.2.  Now, I'm getting odd behavior where input
on the bottom line of the screen is wrapping around to the top.
I'm wondering if selecting "3032" uses the same ROM images as it
used to three years ago.  I doubt there's a bug in the emulation
of VICE itself.
> Ethan Dicks wrote:
> > 
> > I finally verified a ancient project of mine... porting Zork to
> > the PET. I started 15 years ago by beginning to disassemble the
> > 6K game engine that's on track zero of the C-64 Zork floppy.
> 15 years... Now I don't feel so bad about leaving my Light Cycles game
> for about 10 or Flash Attack projects just as long.  Though I think
> programming on the 8-bits is gaining popularity again...

There were large gaps during the 15 years, no doubt.  I started with
a BASIC disassembler from the C= Developers' Disk, and used printouts
to manually go over the code.  I had a resurgence of activity 10 years
ago, then put it away until about three years ago when VICE under
X Windows gave me the tools I needed - I would cross-compile under
UNIX, use emacs to edit the source, and "device 11" under VICE to
directly read from my development directory into an emulated C-64
or PET.  It sped up development 20X at least.
> [snip!]
> > The BASIC 4.0 version is still wonky - I still have a bug that is
> > probably caused by my accidentally using a zero page or other low
> > memory location on 80-col BASIC 4.0 PETs....

I'm wondering if some of the locations in the #2 cassette buffer are
double-booked, or if it's zero page.  One thing I can do is to give
up a couple K of storage higher up and not use *any* memory between
$0100 and $0400 for the ZIP.  If the problem persists, it's a zero-
page issue.

I'm trying to figure out "condition"s in VICE to watch memory
locations only when the PC is above $C000 - that way, I can 
see when the kernel steps on me when I wasn't expecting it.  Any
one ever get serious with the VICE debugger?


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