Wednesday, 27 May 2009

Personal Nightmare 72.out IPS patch(for using the game under DOS)

You may know of Personal Nightmare, a game by HorrorSoft released a while back in 1979.
This game was released for three systems
Dos,Amiga and Atari ST

The Amiga and Atari ST versions were released in VGA
however the DOS version never saw a VGA release and users had to make do with EGA graphics.

HorrorSoft released the game in England, USA and Germany(in English)
however nearly all the DOS releases shipped with a corrupted file namely '72.out'
which made it impossible to complete the DOS game due to a nasty crash.

Lately Kirben from ScummVM began working on support for this game within the AGOS
engine in ScummVM. While the original source code was available parts of it were
written in assembly and needed re-writing. A couple of months ago PN support made it into the SVN trunk
and since then the game is supported fully.

ScummVM was unable to fix the crash in the DOS version of the game since the decompression code
could not handle the corrupt file. However after a long search for the fabled HorrorSoft patch
it became evident that this was lost in time. Kirben managed to make contact with Alan Bridgman
who was able to provide details of the original uncorrupted '72.out' file, which impressively differed by only
one byte and later that day ScummVM was fitted with a nice workaround for the crash. patching the data before decompression
but not affecting the original file.

This is great for users who want to use ScummVM to play the game( who wouldnt :p )
but I thought it might be nice for people who did not wish to use ScummVM and still ran DOS machines or DOSBox.

Kirben kindly provided me with the details allowing me to create a patch for the file.

I created a patch using the IPS patching format as it seems there are clients around for most common OS's
this can be found here http://robertmegone.com/misc/pn/72patch.ips

This needs to be applied over the '72.out' file, and only if your vicarage section crashes.
Although the patched file will still work with ScummVM, I state here that the patch is ONLY designed so that
users can play through the game under DOS/DOSBox.

However if you do not wish to patch the file using this method you can follow the following instructions, using a hex editor
to manually change the single byte.

Change the byte at position 53714(D1D2) from 0x20 to 0x40.

4 comments:

Khaaaaaan said...

1989.

Unknown said...

Cool. I once debugged the game and concluded that 72.out in my copy was corrupt. Never thought that all copies would have suffered from it.

Qbix
DOSBox Project Administrator

Unknown said...

I wonder if this only affected the 5.25" release of the game. It was also released on 3.5" disks later(few months).

Anonymous said...

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