GS WorldView: Spring MMI
.back to GSWV main contents page

Play the (cross your fingers) really fixed version
Crypt of Medea!

by Rubywand

When Laurent Stern posted a request for a working version of this
Sir-Tech classic it was a surprise to discover that, evidently, one did not exist!
After all these years, the bug in the deprotected version remained and
users were still getting snagged trying to cross the ravine.

What happens is that, if you are not carrying too much and should make it
across (by swinging on the rope), the game wipes memory and forces a reboot.

Fortunately, the reboot is via a brute force jump to Slot 6 ROM code; so,
locating the wipe & boot routine in memory was fairly easy-- you look for
a jump to $C600. Once you know where the routine is, you look for places
where the code jumps to or calls the routine and figure out which of these
is involved in bombing the game when swinging across the ravine. (Substituting
Break instructions for the jumps/calls is one way to do this. You swing across
the ravine and the program falls into the monitor and you are told the
location of the Break which sent you there.)

Once it was possible to swing back and forth across the ravine, it seemed
worthwhile to check if the game could be played through to a win.

Well, Crypt of Medea is a pretty decent challenge with lots of stuff to figure
out. (It took a couple hours to make it to the ravine with the rope.)  So, I resorted
to looking for a walkthrough. GameFaqs.com  happens to offer a very good one
written by Douglas Cameron.

One more odd wipe & boot snag was encountered and fixed. After that, play
zipped along until near the very end when a weird problem with timing blocked
the path to victory.

You need to light a bomb, drop it, and get out of the room before the explosion; but,
there just isn't enough time to type in the needed instructions.. (The walkthrough
mentions that getting it done is not easy-- and, the walkthrough is based upon play
using the original disk.)  Somehow, the deprotected copy version had shortened
the time still further.

The fix was to track down the code which sets the time allowed and increase the
value of a byte. The new period is about 24 seconds on a 1MHz Apple II or
emulator-- longer than anyone is likely to need.

So, the bomb worked. Within a few moves, I had escaped Medea's dread
crypt and won!

You can download the new version along with a Save disk and docs in the file
CryptOfMedea_v2001.zip. Let me know if you discover any glitches.


Besides persons and sites already mentioned, thanks go to Greiner Wolfgang
for his May 1988 article about Crypt of Medea in Computist #55, to
the Apple Bandit for doing the original deprotect, and to Asimov
for maintaining a copy.


from GSWV
CryptOfMedea_v2001.zip  (includes docs file)

from Asimov
CryptOfMedea_v2001.zip  (includes docs file)

from GSWV

to top