Games That Use Undocumented Opcodes?

Games That Use Undocumented Opcodes?

Post by Tempes » Fri, 21 Dec 2007 06:26:51


Is there a list of games/programs that used illegal/undocumented
opcodes and therefore won't run on an Apple iie/iic?
 
 
 

Games That Use Undocumented Opcodes?

Post by aiiadic » Fri, 21 Dec 2007 07:42:50


the place to find out will be :

emulator threads on comp.emulators.apple2, comp.sys.apple2,
and perhaps other forums discussing emulators.

Rich

 
 
 

Games That Use Undocumented Opcodes?

Post by Jplcsc » Fri, 21 Dec 2007 16:27:57


XXXX@XXXXX.COM ...

Hi
Yes LADY TUT for example... a headache for me when I try to do it in CopyA
 
 
 

Games That Use Undocumented Opcodes?

Post by Toine » Sat, 22 Dec 2007 18:42:08


Several Sirius Software also... Gamma Goblins does not run on an Apple
IIgs.

antoine
 
 
 

Games That Use Undocumented Opcodes?

Post by Tempes » Sun, 23 Dec 2007 00:27:45


Yeah I ran into many games that wouldn't run on a IIgs because of what
I assumed was undocumented op-codes, but does that mean they won't run
on an Enhanced Apple IIe as well? The reason I ask is that I could
have sworn that I played Lady Tut on my Enhanced IIe back in the day
(alhough it was a cracked version so maybe that is why it worked?).
If there are many games that won't work on the Enhanced IIe, am I
better off "unenhancing" it? I can't think of any games (only apps)
that needed an Enhanced IIe anyway.
 
 
 

Games That Use Undocumented Opcodes?

Post by Toine » Sun, 23 Dec 2007 02:55:10


If I remember well, the 65c02 adds new instructions compared to the
original 6502. If some false opcodes (not used in the 6502) exist in
the 65C02, they will be interpreted and therefore the program will not
behave correctly. That is what I have seen with Gamma Goblins, I have
been obliged to replace the false opcodes with NOPs so that the game
now works correctly on my IIgs.

I would say that the cracker of Lady Tut could have replaced the false
opcodes to make the program understandable. Let's ask JPL ;-)

I cannot recall the name of a game that did not run on a specific
machine due to one VBL softswitch ($C019 or $C070), hardware
differences may explain the issue not only the opcodes.

I believe it is better playing on an unenhanced IIe ;-)

antoine