Writing FreeDOS Programs in C

https://www.freedos.org/books/cprogramming/

by AlexeyBrin • 9 months ago

145 73 9 months ago

dardeaup• 9 months ago

Curious as to whether there are any real-world use cases for doing this (other than curiosity) in DOS. If so, I'd love to hear about them.

grg03• 9 months ago

I have it on my to-do list to install FreeDOS on bare metal to set up a retro gaming box. Tried once, but for some reason the installer failed writing to disk. Anyway, if anyone is making new FreeDOS games, I'll gladly pay for them, and it'll give me an excuse to go down that avenue again.

dlcarrier• 9 months ago

If enabling CSM in your BIOS isn't an option or isn't enough for FreeDOS, there is a translation layer that can get it to run on UEFI hardware: https://github.com/FlyGoat/CSMWrap

comprev• 9 months ago

I used FreeDOS once to run ancient software which controlled an industrial size oven. The client was having an ever increasing challenge of sourcing IDE disks (in 2008) so I was contracted to find a solution.

Eventually we settled on industrial PCs, solid state media and FreeDOS.

It was significantly cheaper than replacing the oven at £1M each.... in 50 of their factories worldwide.

LeFantome• 9 months ago

Lots of solid state to IDE adapties out there too. But great example.

kragen13• 9 months ago

MS-DOS was a reasonable bootloader for Linux and Windows 95; I imagine FreeDOS might be a better one if you wanted to do hobby OSDev. Historically you could get hard real time performance for things like controlling steppers from your parallel port under MS-DOS, but nowadays you'd just use Freeduino or an iCE40. Also maybe brushless motors.

1313ed017• 9 months ago

FreeDOS is no good at all for booting anymore, since BIOS support is increasingly rare. No way to boot FreeDOS (or MS-DOS) from UEFI. And of course also no point in trying to run it on ARM or any other non-x86 CPU. Looks like the future for FreeDOS will be to run in virtual machines only. A bit sad, since running FreeDOS on the bare metal of a 21st century computer (even one from 10-20 years ago) has been a nice way to experience just how fast modern hardware is.

1313ed017• 9 months ago

I hobby-code for DOS, partly because of nostalgia, but much also because it (specifically DOSBox, or DOSBox-X) is such a fantastic and stable virtual machine. No one is going to deprecate even some minor part of the API. And some emulators give you fun features like allowing any screen resolution to be set up to run in fullscreen on a modern monitor (exposed using standard VESA API inside of DOS).

There are some other retro computer or consoles that could probably be just as useful for this. But DOSBox (as well as QEMU+FreeDOS, for those that prefer that) are nice because they have fully open source implementation from the CPU-level up to the user utilities, so there is no need to mess with dodgy ROM downloads or such to get things working.

erremerre• 9 months ago

What do you hobby code? Can we have a glance at it?

actuallyalys• 9 months ago

I suppose there could be a use for programming for computers that would otherwise be ewaste, although I'm not sure how much ewaste is out there that can run DOS but not, say, Linux or a BSD. Lots has already been trashed or recycled, and my impression is that retrocomputing enthusiasts are thinning out the market as well.

nineteen999• 9 months ago

We were recycling e-waste computers back in the 1990's for community groups and disadvantaged users running Linux with full X desktops, internet connectivity (sometimes via multiple dialup modems with EQL load balancing!)

https://www.computerbank.org.au/ <- charity my then partner and I started at the time. Still going strong after all these years, even though she passed away a few years ago.

unnouinceput• 9 months ago

Almost zero, the non-zero ones are about supporting legacy software/hardware. Also I would not touch C on any DOS platform, since the great Turbo Pascal exists for it. Nothing else even compares to it.

jabl2• 9 months ago

(Not development in C)

I've used FreeDOS for doing BIOS updates. In the pre-UEFI days it was common for manufacturers to provide BIOS updates as a DOS executable, apparently with the expectation that the customer would be able to dig up some old MS-DOS disk somewhere.

I suppose nowadays there isn't much use for that anymore thanks to doing FW updates via UEFI capsules. Though at least on the Linux side (LVFS/fwupd) it seems most PC clone vendors aren't on board yet.

Dwedit• 9 months ago

Is there really a difference between writing a DOS program and writing a FreeDOS program? You just need a period-accurate compiler that can target DOS. Maybe OpenWatcom, maybe DJGPP.

With HXDOS, you can also write a Win32 console-mode program and run it on DOS. 7-zip is an example of a program compatible with HXDOS.

johannes12343212• 9 months ago

The "difference" is, that this is the FreeDOS project, thus they focus on that environment.

QuercusMax• 9 months ago

I confess I don't know anything about FreeDOS, but are they trying to evolve DOS for the future, or just make a free bug-for-bug compatible version? Those are very different things.

WalterBright8• 9 months ago

The Digital Mars compiler for DOS is available for free.

https://www.digitalmars.com/

kragen13• 9 months ago

But the GCC, OpenWatcom, and DJGPP compilers the FreeDOS folks recommend are additionally free software, which is of real value to some of us. Zortech C had a reputation for producing better code IIRC, and it could run on an 80286, which I'm not sure the others can?

AlexeyBrin• 9 months ago

https://www.digitalmars.com/download/freecompiler.html

Seems to require Win32 (Digital Mars C/C++ Compiler Version 8.57). Is there a version of the C compiler than can run on FreeDOS or MS-DOS ?

pjmlp3• 9 months ago

Not really, I was expecteding the tutorial to somehow dig out Turbo C, or Quick C.

sgt• 9 months ago

Vibe coders are just going to be staring at this and go... where'd you get that blue mode in Cursor?

grg03• 9 months ago

From the soydev extension.

hedora• 9 months ago

Tangentially related: I was getting awful screen tearing in dosbox with a gl @ 4K@60hz rendering target.

Switching to 1080p@240Hz fixed it. The problem was that 60Hz was close to, but not the framerate the old game asked for.

Narishma4• 9 months ago

The typical 320x200 mode that games used back then ran at 70Hz.

CursedSilicon2• 9 months ago

72Hz actually!

CRT's were "strange" :)

1313ed017• 9 months ago

To the list of compiler listed I want to mention this one as well, that is my compiler of choice for 16-bit C in (Free)DOS these days (because it has a MIT license, it's very small, and it runs great inside of DOS itself so no need to mess with cross-compilation and I know if I have an environment like FreeDOS or DOSBox set up I can both compile and run my code, and I will never have to re-install or reconfigure anything when moving between different host systems):

https://github.com/microsoft/MS-DOS/tree/main/v4.0/src/TOOLS

(Not only Microsoft's C compiler in that directory, but also MASM, MAKE, and a bunch of other tools. 1-2 MB of files and you have an entire toolchain for 16-bit DOS.)

kragen13• 9 months ago

Interesting, "All files within this repo are released under the MIT License as per the LICENSE file stored in the root of this repo," but did they include the source for the toolchain? I may be looking in the wrong place...

1313ed017• 9 months ago

No, but that MIT license does not say anything about sharing the source code, so just sharing the binaries should be fine. (Not a lawyer.)

( * Also thanks for mentioning MIT. My comment said BSD, but I fixed that now.)

anthk4• 9 months ago

On conio.h under GNU/Linux or Unix, it might be mimicked with trivial functions and escape codes.

I did similar stuff with TCL and some at-xy lookalike from Forth or 'print at' from the old Basic.

And rewritting these Basic games into C, TCL or whatever it's really fun (and you can defnitively kill the spaghetti code):

https://github.com/GReaperEx/bcg

You can just run BW Basic for FreeDOS, but that's no challenge...

xx__yy• 9 months ago

I don't know the answer, just asking the question: Is/Was curses available at the time? https://en.wikipedia.org/wiki/Curses_%28programming_library%...

I only remember conio at the time, but without internet you just used what Microsoft gave you. The BBSes I used may have had it, but it's hard to use something if you don't know it exists.

It does look like there is a recent port: https://github.com/wmcbrine/PDCurses

So my guess is curses was not available to DOS at the time, only Unix systems.

kragen13• 9 months ago

I'm guessing that PC-Hack 1.0, the ancestor of Nethack, contains a fair subset of curses, and pdcurses is from 01987 according to the bottom of https://github.com/wmcbrine/PDCurses/blob/master/docs/HISTOR.... But on the IBM, curses mostly solved the problem of porting Unix software to MS-DOS. The problems it solved on Unix, like minimizing characters transmitted to the terminal, papering over differences between terminal types, and setting cbreak mode, just didn't exist.

sedatk• 9 months ago

AFAIK, curses worked with ANSI codes while conio directly accessed the screen buffer. ANSI support on DOS wasn’t enabled commonly as it needed a separate device driver, ANSI.SYS, to work, and it usually made DOS text output slower.

So, even if curses were available on DOS at the time, nobody would have preferred to use it.

pjmlp3• 9 months ago

Most of us coding at the time only cared about Turbo Vision, starting with Turbo Pascal 6. and Turbo C++ 3.0.

Or the other variant being TUI libraries for Clipper.

By 1994, most folks on PC were already doing Windows 3.x, and only using MS-DOS for games.

I only got to learn about curses years later.

anthk4• 9 months ago

in 1994? You wish. Turbo C++/Pascal was widely used under DOS, things truly began to change with WIndows 95 and even until 1997 DOS wasn't fully dead because it had very complex uses with DOS extenders. Windows 95 was an unstable piece of crap and for tons of industrial cases tons of people booted it in DOS mode to launch really advanced software. By 1994 you would even get multimedia CD's made for DOS with ease.

ladyanita222• 9 months ago

Would be nice to have a Rust compiler as well

mrlonglong• 9 months ago

Only if they invent a 64 bit DOS extender.

ladyanita222• 9 months ago

Because of the compiler's memory consumption?

stevefan1999• 9 months ago

indeed there's something similar: https://github.com/dosemu2/fdpp

tracker1• 9 months ago

You can do DOS target software with Rust... it's pretty limited and the tooling around it isn't nearly complete enough to make anything easy. That said, if you want to make something akin to a Zork text mode game or similar there's that... you can also use ANSI escape codes as another possibility for CP437 text mode interaction.

Writing FreeDOS Programs in C

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