Intel's legendary i486 CPU gets unofficial Windows XP support, ISO too

Windows XP Bliss wallpaper 4K render — Official Windows XP Bliss wallpaper in 4K

In case you have not been following, Microsoft is looking to block off really old processors from running the next feature update for Windows 11, 24H2. A couple of instructions, SSE4.2 and PopCnt, are being made mandatory for a CPU to be able to run the next version of Windows 11. Since this is an instruction-level block.

However, these chips were never really supported in the first place so it will only affect those who are used to bypassing the Windows 11 requirements on their ancient systems.

Folks like those, who love to run Windows on old incompatible hardware are in for a treat. A smart German modder, after a lot of hard work, has managed to modify Windows XP such that it will work on Intel i486 as well. i486, also called 486 or 80486 is the first x86 processor to pack over a million transistors, 1.2 million to be a bit more precise, though it released in 1989, which was over a decade old by the point XP was out.

The ISO for the modded XP version was uploaded on the Archive.org website (spotted by Bob Pony on X), though, it is only in German at the moment, and there are a few reporting bugs too.

This is a Windows XP Professional SP3 ISO that has been modified to work on i486 processors. The language is in German however, and there is not an English version yet. The CPU clock speed in Windows system properties is also incorrect, but programs like CPU-Z report the correct clock speed.

NOTE: After the installation is finished, you must copy ntoskrnl.exe and ntkrnlmp.exe from the ISO to C:\Windows\System32, or else the OS will be unable to boot.

An example screenshot of the Windows XP SP3 running inside 86Box (an IBM PC emulator) on an Intel i486SX, which is a low-cost variant of the i486 that had its floating point unit (FPU) turned off, was provided; which is why there is a separate 487SX math co-processor, reported as FPU in 86Box spec details, alongside it. There is also a screenshot of an AMD 486 clone running it.

Intel 486 running modded Windows XP SP3 inside 86Box emulator

In case you are comfortable with German and have a spare 486 system, you can try it out. Perhaps you could even try out the recently open-sourced MS-DOS 4.0.0 too.

However, do not forget the dangers of using such unsupported OS as a recent experiment showed just how vulnerable an old PC like one running Windows XP can be.

Source: MSFN forum