> modern x86 processors can’t boot into BIOS mode anymore

This is false. They still can and happily will. Issue is more about vendor not shipping a CSM image. A modern x86 processor will happily run real DOS just fine.

Thank you for the correction! I saw multiple news articles several years ago saying that Intel would be dropping support for BIOS mode by the end of 2020, but it appears they've been dragging their feet. In the meantime, they seem to have been making moves in other ways, such as not supporting BIOS mode when booting with integrated graphics on 11th gen processors ( https://www.asus.com/us/support/FAQ/1045467 ).

You might get this all the time, but I saw your username and thought no way that's the old palm guy. But I clicked on your profile, and you are the old palm guy!

I used your apps back when I had a Tungsten T5, and Treo 680. :)

http://dmitry.gr/?r=05.Projects&proj=27.%20rePalm :)

This is the most incredible thing I've ever read. I'm astounded at the level of work you've put into this.

Amazing read, thank you Dmitry. One typo for pedantry's sake? This:

> It as possible, but not documented.

Should probably be:

> It [is|was] possible, but not documented.

Intel's been threatening to cut off everything non UEFI for a while... I think I read the iGPU in Alder Lake doesn't work unless you're running UEFI?

It might not have happened yet, but it seems inevitable.

That's probably because it doesn't have a traditional VBIOS.

...which makes me wonder whether it's possible for the community to write one, given how much docs and source code Intel have released for their GPUs. Of course, how VGA-compatible it is is another thing to consider.

That depends on what one means by "booting into BIOS mode". CSM is a shim than makes UEFI firmware look like BIOS to the OS (or, well, bootloader) and to x86 code in various option ROMs, so you are always booting into UEFI.

Really booting without UEFI being involved in the process would require completely different firmware image.

Intel officially pulled support in 2020-2021.

It still works fine, just not officially encouraged by Intel

The big market for this is K-12 schools.

Microsoft has a licensing program for .edu that doesn’t require an “embedded” hardware license. There are also many places using Neverware to provide Chrome desktops while using the some warranty services, etc that they have with PCs.

If you buy alot of computers, you can get desktops crazy cheap. Big enterprise buyers get low-spec desktops for ~$225 without windows or $300 with. If you don’t care about power/footprint, they are the best value thin client. Schools are huge PC buyers, some districts have >300k students, so you’re easily talking 40-70k PCs annually.

Ok, but why the hell FreeDOS?

Why FreeDOS vs nothing or why FreeDOS vs Linux? The former, because some OEMs have agreements with Microsoft that prohibit shipping systems without an OS. They found the loophole that they could ship a free OS as a placeholder. Why not Linux? I guess it was easier at the time and they then just kept shipping what was already working. It was never intended to keep the original OS anyway (and in particular, Linux users tend to be opinionated and install their favorite distro anyway).

I suspect it's more bland than that, they need to be able to have a booting/working system otherwise the customer is going to call up support and say their computer isn't booting or that it's saying "no OS found" type messages. It's just to cover themselves, that's why they include enough Linux to be able to load a PDF reader. It should be easy enough to do d:\setup.exe with a USB that has a Windows installer on it, with this setup.

Windows installers are bootable these days (from DVD or USB; doesn’t matter); they haven’t been runnable from DOS for a couple decades now.

At any rate, even if you did find some OS you could install from DOS, you’d be installing it into the QEMU image if you installed from FreeDOS on a system with this arrangement. There’s no way to get back to the bare metal hardware from FreeDOS here.

Yeah, but why not have something that just uefi boots into a barebones grub2 and then cli only debian-stable and bash shell?

Forget the DOS part.

It's probably more like they have DOS support contracted out to some vendor. And when the systems upgraded to the point of not being able to run DOS natively the vendor built this franken-OS to fulfill the contract.

Renegotiating the contract to something sensible like "don't run DOS anymore" was probably hopeless in the face of the bureaucracy, or risked losing to contact.

Maybe it is for customers running weird old legacy hardware (e.g., lab devices, manufacturing, that only runs on DOS).

Weird old legacy hardware that only runs on DOS generally requires real-time access to stuff like ISA cards or parallel/serial ports, so this wouldn't work for that use case since the computer doesn't have any of those.

I have a weird old nylon cutting machine connected to a DOS machine over a serial port. It would not work with a USB/RS-232 adaptor?

USB-serial conversion would add a measurable amount of latency, and the access to USB hardware would occur under a non-real-time OS. Whether the setup "works" would be highly hardware-specific. There are modern industrial "PC" boards that are essentially a i586 implementation in a SoC and can run these workloads far more reliably, while consuming a lot less power compared to old x86 hardware. (They're also of interest to retrocomputing enthusiasts, for largely the same reasons.)

It probably won't if they do weird things with the flow control pins or if the timing really matters, but serial is far more likely than parallel to keep working.

Yeah this is why industrial PCs still have those physical ports.

Depends on the adaptor too. Cheap ones only have Rx and TX pins . The rest of the pins are not connected. If your device only used Rx and Tx it would work fine . If it uses functionality of other pins make sure you get the right adaptor

Spend no less than $20 on a USB to serial converter and you'd probably be fine. Anything with an FTDI chip in it are the best. Anything with a Prolific chip has a good possibility of being counterfeit will either not work well or the legit driver will try to brick it.

FTDI pushed driver updates that bricked counterfeits... https://www.theregister.com/2016/01/31/ftdi_accused_of_brick...

That's orecisely how we run our thread 3D printer. It even has a serial (UART) to USB chip on board and it's connected to a RPi3 boc running Linux and Octoprint.

No, the FreeDOS HP option has always been used by the customers who did not want to pay a Windows license, because they wanted to install a different operating system, usually some Linux variant (the option to install a pirated Windows variant was also popular in some parts of the world).

Dell has the Ubuntu option for many computers, but for those who do not want to use Ubuntu, like myself, there is no difference between the Dell Ubuntu option and the HP FreeDOS option, because such customers will always install their own preferred OS, immediately after the purchase of a new computer.

I'm the author of the article; It's not actually usable for that. The way the Qemu VM is setup there is no way to interface with the outside world at all. The only way to get any data in or out of that VM is through the keyboard and screen.

Would those apps work inside QEMU though? Is it configured to properly pass through the parallel port?

Maybe, but wouldn’t the customer have to know how to run QEMU? I am imagining a customer who wants to just replace an old machine while changing as little as possible.

Since this install is based on QEMU running in Linux, it would not meet that need.

The end user need not know it is QEMU atop Linux. They see and use DOS.

Yes, but inside a VM. What access to real hardware (e.g. to communicate with the outside world) does the user get?

Whatever is configured with QEMU: everything if that was the use case.

But it looks like their setup is not configured to give access to hardware, at least I didn't see any options on the command line.

Highly unlikely, without really messing around with it.

FreeDOS is known to not run well inside of virtualization. A proper host install would be far more capable.

That is not true.

In fact, if you just boot FreeDOS 1.3 in VirtualBox, you'll see it detect the virtual NIC, load a TCP/IP stack and acquire an IPv4 address, then report it.

It is mostly developed and run inside VMs these days, AFAICS.

But a proper host install is not possible on modern hardware.

Hypothetically if you wanted to use something like FreeBSD, Dragonfly BSD or maybe OpenSolaris? This is a big reach.

And I guess FreeDOS doesn't support booting by UEFI as well

(I mean, can it even?)

It would involve essentially reinventing UEFI CSM as part of this hypotetical UEFI FreeDOS.

"FreeDOS assumes a BIOS, and does not work with UEFI."[0]

[0]http://wiki.freedos.org/wiki/index.php/UEFI