VOGONS


cpu grp5 illegal call 7

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First post, by RayDream

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A newbie in programming here,

I had encountered this grp5 illegal call 7 problem as I tried to run an old game developed by taiwanese company 1994 (the game is not tested by dosbox).

The game is called DIF2, dosbox shows grp5 illegal call 7 while vdmsound is able to run it, however the speed will be messed up, playing normal speed in title screen, but a reduced speed in gameplay. I had tried SPEEDSET.exe (a speedup program), however due to the badly programming in the game, it slowed again after some pt in the game.

The game can be downloaded here:
link deleted by MiniMax

Please help!

Last edited by RayDream on 2008-10-02, 15:08. Edited 1 time in total.

Reply 1 of 13, by wd

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It won't work in dosbox.

Reply 2 of 13, by RayDream

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any ways to make it work?

Reply 3 of 13, by wd

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Don't know, there are several slowdown programs that you can use together with vdmsound.

Reply 4 of 13, by catchaserguns

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Any link to abandonware is forbidden. We do not support abandonware on this forum. Go to the website where you got the game and ask them.

Reply 5 of 13, by RayDream

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The fact is I own the original B-disk 😀 Will it help if I share the program for anyone who can troubleshoot it?

Reply 6 of 13, by MiniMax

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Seems like it is a problematic game for DOSBox:

http://www.dosbox.com/comp_list.php?showID=1592

DOSBox 60 seconds guide | How to ask questions
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Reply 8 of 13, by h-a-l-9000

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> There are good reasons for not supporting the intentional use of illegal CPU instructions.

Tell Microsoft 😉

1+1=10

Reply 9 of 13, by rcblanke

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Maybe try this altered DOSBox version (as proposed by jmk) for this particular game. Please don't use it for anything else.

Reply 10 of 13, by eL_PuSHeR

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Yes, it works with this one.

Intel i7 5960X
Gigabye GA-X99-Gaming 5
8 GB DDR4 (2100)
8 GB GeForce GTX 1070 G1 Gaming (Gigabyte)

Reply 11 of 13, by ripsaw8080

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I had an idea of how to make this game more DOSBox-friendly, but it involved hacking the executable, and that's not the best approach. I took the same general idea and turned it into a patch loader program that makes the necessary modifications in memory, so nothing is permanently changed. Run DIF2FIX.COM from the same directory where DIF-2.EXE is located. The included source code has some comments explaining the modifications.

RayDream, please check if the loader works correctly with your original, unmodified executable, as the one I tested with has clearly had its copy protection neutered. The game sometimes locks up when exiting back to DOS, but that happens even without my program.

Reply 12 of 13, by eL_PuSHeR

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Great work! Your patch works with official DOSBox 0.72, but I also tried an already cracked executable version.

Intel i7 5960X
Gigabye GA-X99-Gaming 5
8 GB DDR4 (2100)
8 GB GeForce GTX 1070 G1 Gaming (Gigabyte)

Reply 13 of 13, by RayDream

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yea it works! thanks a million! You save my life!