How can I extract this fancy VGA font?

May 15, 2014 1:38 AM

I have access to an old Toshiba 386 PC (T2000Sx) with an extremely unusual VGA system font; which I would like to recover as a font file and document in a web site. How can I write a program which reads the font data from VGA memory and writes it to the floppy?

The system barely boots from floppy, has little memory (1MB base + 9MB extension) and no hard drive. It used to boot Debian 2.1 via a ZIP drive on the parallel port, but that does not seem to work any more.

The question is a combination of:

1. are there (DOS) programs to do this already? (I have not found any yet; but maybe there are?)

2. programming tools: which language/compiler can I use? Obviously this machine won't run any modern OS, so GCC / VS is out of the question. I had some experience 20 years ago with writing .COM executables manually from assembly, but it is rusty; are there any better programming tools nowadays?

3. VGA standard: at which address in the address space can I find the font data, and how many bytes should I read? I have not found this yet in other sources online.

posted by knz to Computers & Internet (7 answers total)

ROM extension extractor (ree) might help. There appears to be a prebuilt DOS executable in the bundle. As with any random download, I don't know how safe it is to run, so you might do some research, first.
posted by Blazecock Pileon at 2:02 AM on May 15, 2014

OK, you've left me super-curious. As with questions about cats, I demand a picture - can you take a photo?
posted by Zarkonnen at 2:27 AM on May 15, 2014 [1 favorite]

I agree with Zarkonnen. In fact, if you provide a photo, it wouldn't surprise me if someone could just point you to the ROM (maybe someone in this thread?).
posted by barnacles at 2:57 AM on May 15, 2014 [1 favorite]

The VGA font is pretty easy to extract for a 16-bit DOS program. You set some registers, call int 10, and it tells you the address where you can snarf it down from video memory. If you've ever poked around ASM in your life, you could probably do it entirely within debug without ever writing a program file, without much trouble. (I think debug has a function to save memory ranges to disk, right?). Honestly the hardest part is probably going to be getting it from the 386 onto a modern computer.
posted by aubilenon at 3:09 AM on May 15, 2014

Response by poster: I will try to make a photo later today/tonight.
Although I am not optimistic about finding it elsewhere, as I am also a hobbyist of system fonts and never saw it online yet.

@aubilenon: once the file is on floppy, all is set; I have a USB floppy drive to plug anywhere else.

Also if push comes to shove, I know how to use zmodem over the serial port and minicom on the other side.
posted by knz at 5:29 AM on May 15, 2014

There was an old DOS utility called FONTEDIT that I remember playing around with. It would let you edit the system font however you pleased, and you could save the result as EXE files that would change the font when run.

I don't remember if it defaults to the current system font or just a standard font, but if the former is the case you could just "save" your system font, then run the resulting EXE in a VM to capture a bitmap of the letters, or something along those lines.

I'm pretty sure this is the one I'm thinking of.
posted by neckro23 at 2:17 AM on May 16, 2014

Response by poster: I can't seem to power up the laptop at the moment, however I found one and another screenshot of the same font from the same latop line.

If you have any suggestion as to which font this is, please let me know.
posted by knz at 4:35 AM on May 17, 2014