Like, MS-DOS? How? It doesn't seem to have had an x86 CPU to run it on. (I'm assuming this predates emulation like we might use today for that kind of thing.)
Edit: Oh, kept reading the wikipedia article and found the mention of an 8086 expansion card. That's cool:)
We had PC emulators on the 68000 based Atari ST in the 80s. No extra hardware needed, but very slow! And I'm sure that emulators was a thing from the very first computers.
Some systems also had expansion cards with an x86 processor on them. A more recent example would be Sun's SunPC and SunPCI cards -- you plugged these in a SBus or PCI slot, and ran x86 code on a real x86 processor. IIRC that's actually what the AT&T Unix PC did, too, but I'm not sure (I never owned one).
I had one of these in my Amiga 500: https://www.edsa.uk/blog/the-kcs-power-pc-board
(this was before the PowerPC CPUs appeared on the market, so the name wasn't as confusing as it sounds today).
In addition to being a PC board, it also doubled as a memory expansion and RTC when you were using the host Amiga system.
The ST was at least a cost-effective way to emulate a PC very slowly. Not so much for SoftPC for VMS, which cost as much as an entry-level ST for the software alone:
But hey, MS-DOS 6.2 and Windows 3.1 would have at least both fit comfortably on a single TK50 cartridge or 9-track open-reel tape, so at least you weren't stuck in front of the console swapping floppies waiting for the products to install.
That must've been it! My friend and I bought them used at a yard sale at the end of the airport from a couple who had worked at TWA - they were former TWQ machines. I don't think we ever opened them.
I have a 7300 and a 3B1 (7300 is single half-height hard drives, 3B1 is two HH or one full-height). One has a Combo Card (RAM and serial) and a Floppy Tape card, I can't remember what the other has, but cards have been pretty thin on the ground. A DOS-73 or network card would be extremely nice to have.
The emulator actually started life because I couldn't find a machine for sale at a price I could afford, but the manuals were on Bitsavers. Someone later sold me the 7300 and 3B1.