When started with DOSBox debugger there is a message which is writen for many times.

INT10: PutPixel unhadled mode type 4

Is this some graphic mode unsuported gby DOSBox?

If it is will it be supported in future?

If this is not a DOSBox unsuported stuff what could it be?

Ognjen Milic

usually it's an error message printed by the game in vesa mode using bios calls.

Game is still broken, but now DOS4GW reports error. Screen capture in the attachement.

Try with xms/ems disabled, and use dos32a, maybe it works then.

What is dos32a?

It's a replacement for dos4gw, see
http://dos32a.narechk.net/index_en.html

I have binded dos32a with game but the result was the same.

I don't hav debugging version of the dosbox newest cvs build and
I can't compile the source with minigw.

Ognjen

You shouldn't need to bind it, and if it was working you would get a different error than "DOS/4GW..."

Try:
dos32a gamename.exe

Where gamename.exe is whatever you normally run to start the game.

I wanted to say that game does not work with dos32a too.
Binded or called within command line the screen is blank, and after few seconds dosbox windows are closed.
DOSBox console reports ilegal read from several addresses, and
Stack segment zero

Ognjen

The error is caused because of unhandled Interrupt service

INT 15 AX = BFDE BX=8

This is som undocumented DVDOS4GX.dvr service

Shouldn't this service routine been loaded upon loading the DOS4GW?

Ognjen Milic

No, this is just the Desqview-check:
Int 15/AX=BFDEh/BX=0008h DESQview/X 1.02+ - DVDOS4GX.DVR

Is this ok to be unsupported? Let me know to search further.

Yes 😀
Desqview is an application, i think it supported multitasking of
dos programs.

You could try to see what's happening at the int6, which opcode
triggers it (maybe posting the disassembly around it).

While debugging I came to very obscure behaviour.
When procedure returns i return on address where are only
zeros (code hasn't beeen written in here yet).

I'll try to figure out why.

Do You have any suggestions?

Ognjen

Hm, if you have a heavylog of that procedure you could see
where the stack gets wrong (contents or stack pointers).

Something have definitely gone wrong with stack. That return address is part of file name wich is pointed by ESP.

Ognjen Milic

Interesting. It is probably the bug in the game.
The string with the file path c:\igre\sport\nba95\install.dat
overwrites the return address. Probably the space for it is staticly determined just by subtracting esp, but maybe something goes wrong during string length determination.
Game succesfully starts from lower directory (c:\igre\nba95).

Could this be a DOSBox error?

If this could be I will search more.

Ognjen Milic

Now it returns message

cdromcheck - CDROM STATUS NOT RETURNED and exits.

Ognjen Milic

> Game succesfully starts from lower directory (c:\igre\nba95).

Sounds much like a gamebug, you could try to test what it does
for longer path names under real dos.