hmm, not that much reaction 😀
Anyway, does anyone know of a program that "changes" the hdd serial number for either dos or windows 3.x?

I wrote one once, but it was so long ago that I'd never be able to find it even if it still exists on a disk somewhere 🙁

It's really easy to do - there's an interrupt you can call in DOS to set the serial number to whatever you want!

If any games actually use it for copy protection, then the programmers were pretty naive.

Problem is that in Dosbox there is no serial, so I thought either someone will add serial number emulation to dosbox, or there might be a program that does it. Since I'm no programmer this is a no no for me 😀

The developers were not only naive but also very shortsighted. The full game was only availlable on floppy, when you installed it, the hdd serial number was written to the game exe both on the floppy and on the hdd. To be bale to install the game again on another computer you needed to uninstall it from your hdd, to clear the floppy version without the serial again. Problem was that when you just killed Windows and wanted to reinstall it you allready had problems. If you formated your hdd, you were screwed. That's why I always made image copies of the floppy 😀
That'S the game, btw:
http://www.sdispace.com/inspace.htm
works also in Windows XP, only the joystick doesn't work anymore there and I really liked it with that. The whole reason I even installed Windows in Dosbox and the serial number issue is the only reason I installed Windows on an hdd image 😀
(so, alos the reason I ever got to write a Win3x guide for Dosbox 😀)

As you mention the serial number being destroyed through formatting,
this should be some field in the boot sector/MBR. When using disk
images, everything should work as it is solely based on the information
that is present on the disk images.
As retrieving the serial number involves reading a disk sector, this can
not be achieved by "plain" dosbox.

Yeah, an hdd image works fine without problems.

As for plain Dosbox I tought that something like the -label switch might be doable, but if you say that is not achieveable...
-> the "need" for some kind of tsr that might emulate it... But well, it is NOT important 😀

Hm, you could write a TSR that intercepts int13-calls (maybe int25/26
as well, depends on how they access the disk) and look for boot
sector reads, and then fill in the serial number. Might work if the SN
is the only thing that game is looking for.

you could write a TSR that intercepts int13-calls

There's the catch 😀 I could if I'd know how to program 😀
But if anyone were brave enough to go about coding something like this I'd be happy to help with testing/supplying the game image.

Would it be possible to hex edit the game executable to expect a blank serial number (or whatever it gets when it queries DOSBox)?

In dos_ioctl.cpp, you can specify serial number.
Change it (0000-1234) to another you want then compile source.
mem_writed(ptr+2,0x1234); //Serial number

hmm, I don't know what it gets from dosbox since dosbox doesn't give any serial number. But I'll try that, only have to use a real floppy again. My floppyimages only seem to work when I boot from an hdd image (see Mounting Floppy images not working correctly anymore?).

I'll try that with the source change.

Edit2: So, the serial should by default be 1234? why does no Dos tool show that serial number?