Newsgroups: comp.sys.apple2
Path: news.weeg.uiowa.edu!news.uiowa.edu!hobbes.physics.uiowa.edu!zaphod.mps.ohio-state.edu!caen!uunet!munnari.oz.au!labtam!philip
From: philip@labtam.labtam.oz.au (Philip Stephens)
Subject: I've fixed a bug in Lode Runner GS
Organization: Labtam Australia Pty. Ltd., Melbourne, Australia
Date: Thu, 26 Nov 1992 02:36:15 GMT
Message-ID: <1992Nov26.023615.8822@labtam.labtam.oz.au>
Lines: 29

  A week or so ago I made a brief mention of a rather insidous bug found in
Lode Runner GS.  For those of you who remember this game, I'll briefly
describe the symptoms of the bug: whenever a robot ran through a dug-out brick
from left to right, the game would think the brick had been filled back in!
Surprisingly the bug did not reveal itself until level 156 (level 6 of the
Championship Lode Runner levels for you Lode Runner affectionados), but the
effect was to render the level uncompletable.

  Anyway, I decided to put my hackers hat on last night and track down the
cause of this bug.  It turned out to be a flubbed compare accumulator immediate
instruction--evidently the authors of the GS version made a mistake between
disassembling and reassembling the source code.  
  Anyone who has a copy of this game on a 3.5" disk may be interested in the
bug fix.  So get out your favorite sector editor and do the following:

  1. Read block $14 (20).
  2. Look at byte $1FD in that block.  It will be the value $02.  Change
     this to the value $01.

  That's it!  Don't you hate how a single byte can cause so much trouble!
Now I'll be able to finish the game and become the Lode Runner GS champion...
  
  :-)

-- 
| Philip Stephens, Systems Programmer. | %%%%  %     Labtam Australia Pty Ltd |
| Address:  43 Malcolm Road, Braeside, |   % % % %     "Applied Ingenuity"    |
|           Victoria, 3195, AUSTRALIA. |  %  % %  %  We make the fastest RISC |
| Internet: philip@labtam.labtam.oz.au | %%%%% %%%%% X terminals in the world |