View source for Hacking ST News shell to remove Write-Protect checks

'''Guide to fixing ST News Write-Protect check'''

If you fancy a dabble here's a quick tutorial on how to patch any issue of ST News that refuses to run from a folder within STEEM (and in theory any other emulator) on an emulated h/drive partition.

It removes the Write-Protect check that Richard (or Stefan?) used to perform during the heyday of Atari ST viruses.

Also there are two other patches needed for Issues 4.4 and 5.1 which checked they were being run from a floppy-disk only .. same code to remove, just slightly different location within the main PRG.

'''Hacking Tutorial'''

  1) MONST - open up as BINARY, the '''ST_NEWS.PRG''' file (unpacking it first if necessary)
  2) Press '''TAB''' to move to text display
  3) Press '''G''' to search for text
  4) Look for "You should" and press Enter
  5) MONST will dump you in the middle of the "write-protect" text for the dialog box.  Move the cursor up until you see the bytes '''6606'''
  6) '''TAB''' twice back to code window, press '''ALT & M''' and type ''M3'' so that the ''M2'' window shows you the same location that is in the text window.
  7) There's the naughty '''BNE.S ($6606)''' code
  8) So '''NOP''' it out by replacing the '''$6606''' with good old '''$4E71'''
  9) Press '''ESCAPE''' after editing
 10) Press '''S''' to save as binary
 11) Parameters: ''FIXED.PRG'' and then ''M0'',''M1'' for the start & end.
 12) Test '''FIXED.PRG'''

The above 2-byte change was tested and worked on the following issues: ST News 2.8, 3.1, 3.2, 3.3 & 3.4

However, although the code was present (and fixed) in both 4.4 & 5.1, there was another check present in both these issues which checked that the disk was present as well.

Performing the above routine as above but replace the text "You should" with "DISK A" and patch the same.  All checks removed and issues will run under STEEM with no problems.  Be wary of Issue 4.4 as there are two checks for Drive A inside (fell for that one myself!).

MUG U.K(tm) - April 20th 2004 - [[http://www.mug-uk.co.uk My site]]


[[Category: How To]]
[[Category: Programming]]