45 Year Old DOS on a New Intel CPU Without Emulation

The 80186 chip wasn't backwards compatible which is why it wasn't widely used in PCS. Intel quickly learned the lesson that backwards compatibility was key to long-term success and reverted to that in the 286 onwards.

I once managed to run FreeDOS on a Xeon E-2224 machine just for fun. So yeah, it’s totally possible

RIP OS/2 compatibility in x86-64 processors

6:16 no, it doesn't waste space, this is a myth. Because the chip runs microcode and the actual architecture is very different than an actual 8086. It only wastes a bit of ROM for a couple of instructions, that's almost nothing, most of the space goes to cache, but there are plenty of space for smaller things like a fixed ROM made out of simple diodes. The old instructions can be perfectly emulated/interpreted on modern hardware by newer CPUs without wasting any extra space for any logic via the microcode mechanism. There's absolute no reason to remove them. The source for this is Jim Keller, he said that.

You may think you chose the 'No sound' option for Doom, but I could still hear every sound effect perfectly....

Dos is fully usable on new hardware, but when you start getting into drivers, you run into problems. Same with old windows versions. In most cases you wont have drivers at all, unless random people online chose to write new ones for the more commonly used parts. AC97 for example. Every computer I've built within the past 30 years has internal AC97 sound. If there isn't a driver for DOS yet, someone should have worked on it at some point.

The backwards compatibility makes x86 processors always definitive. x86 users aren't missing out on MMX, SSE, and SSE2, even when they get the latest processor.

memes aside, the ability to run legacy software is key to a lot of infrastructure

It looks like at least two things are needed for a modern intel based or amd based computer to run old MSDOS. One thing is the computer needs to have a legacy bios mode available in its firmware and a legacy boot mode available in its firmware. Also the graphics card will need to have a legacy mode that it can be enabled. It is amazing that this backwards compatibility has been maintained for so long. Especially with planned obsolescence of so many items.

My PC might still be able to run DOS, but it also sadly fails at Windows 95, as it's way too fast, which makes the (unpatched) security code fail horribly. 😉

Intel will never be able to rid the older x86 instructions simply because the commercial/industrial scape wont allow it for at least another 20 years or so.

Brilliant. This kind of stuff shows how we walk on the shoulders of giants whenever we do anything with computing.

This is a big reason why I'm a bit of an x86 fanboy. Yes, the syntax for x86 asm is bad, but it's rare to write x86 by hand anymore. The compatibility is beautiful. I often bring up embedded ARM systems(usually zynq or zynqmp) and specifying devices in device trees, configuring u-boot is tiresome. This is why for instance with OpenWRT you see one build for x86 and 50 others for variants of ARM/MIPS devices.

You bought a NAS to play Doom..... I approve 😆 Side note: Meanwhile Mac users have been forced into emulation to enjoy anything made before 2007. Kind of a shame, all my favorite games growing up rely on PowerPC architecture ☹️ Edit: Antonyms are fun! 😀

What's cool: you can easily get MS-DOS to boot into any other program by creating an Autoexec.bat file. You can even make a simple menu, to let the user select what program they'd like to use.

A lot of new laptops don't have any CSM mode so you can't run DOS at all...Soon desktops won't have it either.

We need an i7-8086K running DOS!

Thanks for the fun video. I actually used to use dos 1 and over time about 12 versions on those old chips.

I love your vid! Gives me real old school vibes. This is also quite fascinating to me, I remember running Windows 98 SE on a 2012 Ivy Lake Laptop, but I would never thought that something as recent as a 2016 Intel CPU would be able to run an Operating System as old as DOS!

That's exactly why I believe that DOS is the innate operating system of the x86 architecture