Check out MS-DOS running natively on modern hardware, showcasing the incredible backward compatibility of x86

[zohaibahd]

In brief: A YouTuber has demonstrated the ability to run the venerable MS-DOS operating system and classic games directly on modern computer hardware without any emulation. This blast from the past showcases the remarkable backward compatibility that x86 processors have maintained for over four decades.

The video, posted by YouTuber Inkbox, walks viewers through the process of booting up the ancient, pre-Windows MS-DOS 8.0 and installing games like the original Doom from 1993 on a system powered by an Intel CPU. The 16-bit code is all natively executed with zero software emulation required.

In the video, Inkbox highlights that this unlikely compatibility stems from the design decisions made by Intel in the late 1970s. When the company introduced the groundbreaking 8086 processor, the chip architects ensured it could still run software developed for Intel's previous processors. Little did they know that this backward compatibility would become a defining trait of the x86 architecture for decades to come.

The true turning point, Inkbox says, came in 1981 when IBM chose a variant called the 8088 to power its seminal IBM PC. Over the next decade, the vast majority of personal computers were IBM compatibles built around evolving x86 processors like the 80286 and 80386. To ensure legacy software kept working, each new chip adhered to the original 16-bit real mode used by the 8086.

Fast forward to today, and even the latest 64-bit x86 CPUs from Intel and AMD still boot up in that ancient 16-bit OS before switching to their modern operating modes.

Inkbox used an Icewhale ZimaBlade Mini PC for the demo. He kicked things off by installing a 16GB RAM module and an Intel Celeron N3450 processor. But despite the PC's array of modern ports, it still lacked a floppy drive, which presented an initial hurdle.

However, Inkbox circumvented this by using the Rufus tool to create a bootable DOS disk from a regular USB flash drive. After configuring the BIOS to boot in legacy mode and selecting the USB drive, he successfully booted into the "bare metal" MS-DOS 8.0 environment with relative ease.

He was then able to install and play games like Doom and Pac-Man.

The whole thing is rather amusing, but it also highlights the incredible inertia behind x86 computing. Intel has tried to transition to new processor architectures like Itanium but never succeeded. Even now, the chipmaker's attempts to streamline future x86 chips by removing some legacy instructions are an ongoing process.

To run MS-DOS and vintage programs yourself, you'll need a PC that can boot in legacy BIOS mode. Using the Rufus tool, you can follow the instructions in the video to create a bootable USB drive with DOS and run any classic games or apps.

Permalink to story:

Check out MS-DOS running natively on modern hardware, showcasing the incredible backward compatibility of x86

 

[Art C]

This is an embarrassment, actually. The ability to run in real mode takes up space on the chip. It's time for AMD and Intel to drop the ability to boot into anything other than long mode (64-bit protected mode).

 

[Dimitriid]

Umm, that's kind of been the point of Linux since almost as long in the early 90s?

Except Linux is actually competent and far better supported when trying to handle some other architectures like ARM which can be far more usable overall.

 

[Guillermo Belli]

Well, the N3450 is from 2016 so not exactly "modern".

A lot of new computers, especially portable computers, don't allow to boot in non-UEFI mode as they don't allow to disable "Safe Boot". In these computers booting DOS is not possible, or at least not easy.

 

[Dreadcthulhu]

This is an embarrassment, actually. The ability to run in real mode takes up space on the chip. It's time for AMD and Intel to drop the ability to boot into anything other than long mode (64-bit protected mode).

But how much space? An entire CPU from the DOS era is basically a rounding error when talking about the transistor budgets of modern CPU (as an example, an Intel 486DX2 had 1.2 million transistors; a Zen 4 chiplet has ~6.57 billion), so the transistor needed for that backwards compatibility would be even less. Its probably so trivial that is not worth the engineering time to remove.

 

[MobileJAD]

MSDOS 8.0 was not pre Windows, it came bundled with Windowd Me as, like Windows 95, it used MSDOS to boot the system. The last retail copy of MSDOS that was sold independetly was MSDOS 6.22

 

[snOrdquist]

Not sure if it's colonialism that'll let you also run DOS on a display power control logic subset of the logic there, but I have to think the availability of this error mode is more a subset for an article more about booting into btrfs images, QUBES environments, VM of 6 varieties, and possibly a forward move of Win11Pro to a nicer M.2 SSD.

 

[lycanthoss]

This is an embarrassment, actually. The ability to run in real mode takes up space on the chip. It's time for AMD and Intel to drop the ability to boot into anything other than long mode (64-bit protected mode).

It costs basically nothing to support real mode when you already support indirect memory addressing. Instead of mapping indirect memory addresses to real memory addresses you can just map real address to real address. Real mode is not the problem with x86. And regardless, every ISA has problems and in the end they all perform similarly. However x86 additionally retains compatibility on desktops, servers and laptops.

 

[Vanderlinde]

MSDOS 8.0 was not pre Windows, it came bundled with Windowd Me as, like Windows 95, it used MSDOS to boot the system. The last retail copy of MSDOS that was sold independetly was MSDOS 6.22

The included MS Dos through windows ME was just 6.22"+" - it had no new features other then compatibility with ME - which could only be triggered by a registery hack to natively boot into MS Dos.

 

[haunter]

Well, I was playin Prehistorik 2 on 486 - 50MHz, dunno how much RAM - 4MB? Now my Asus router has 4 cores at ~1800MHz and 512MB dunno how fast ram. So yes, this can run DOS :-D

 

[Ben Myers]

This is a telling phrase: "After configuring the BIOS to boot in legacy mode..." LEGACY mode.

I recently completed a project for a client, replacing a dead 486 with a Dell Optiplex desktop model running a 7th Gen Intel i5 CPU, manufactured in 2017. The 486 drove an industrial device through a serial port running MS-DOS 6.22. That's what the Optiplex does now, booting DOS from a small SSD. Intel has taken great pains to assure that modern serial ports are compatible with the original de facto serial port standard of the IBM AT.

As prior research for the project, I needed to find the newest computer with a serial port, also capable of running DOS 6.22. Because the minimum memory of the system is 2GB, and HIMEM.SYS hangs, I substituted HIMEMX.SYS from FreeDOS, using a command line option to limit it to ONLY(!) 512MB,

After the Intel 7th gen, selecting Legacy Boot seems to disappear from the UEFI (BIOS) firmware, and it seems to be impossible to install MS-DOS 6.22. I need to research this further, if and when I find the time.

 

[Ben Myers]

Well, the N3450 is from 2016 so not exactly "modern".

A lot of new computers, especially portable computers, don't allow to boot in non-UEFI mode as they don't allow to disable "Safe Boot". In these computers booting DOS is not possible, or at least not easy.

You are correct. See my post below, telling a little about my experiences.

 

[Bamda]

This is an embarrassment, actually. The ability to run in real mode takes up space on the chip. It's time for AMD and Intel to drop the ability to boot into anything other than long mode (64-bit protected mode).

Speak for yourself. Some of us still want that function.