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Category Archives: 286
IBM XENIX 1.0 Incompatibility Details
Some time ago I wrote about IBM PC XENIX 1.0 and why it won’t work on 386 and later processors. Thanks to a kind reader, I’ve been able to analyze the object files used to link the kernel, and I believe … Continue reading
Posted in 286, 386, Microsoft, Xenix
21 Comments
Better Late Than Never
Better late than never, although in this instance, it’s really really late—about thirty years late. In the world of computing, that is eternity. The talk is about the new CR4.UMIP control bit documented in the latest (revision 58) Intel SDM, … Continue reading
Posted in 286, Intel, x86
13 Comments
Basement Finds
The other day I attacked an old and long forgotten 286 PC stashed away in the basement. The PC is dead because the power supply blew years ago and the motherboard has a non-standard power connector. But the case was … Continue reading
Posted in 286, ATi, PC hardware
10 Comments
IBM XENIX: One Step Forward, One Step Back
A while ago I wrote about why IBM PC XENIX 1.0 can’t work on any CPU other than a 286. But not content to leave well enough alone, I attempted to patch this version of XENIX so that it would … Continue reading
Posted in 286, 386, IBM, VirtualBox, Xenix
5 Comments
Forward Compatibility, Landmines
Several years ago, after attempting to get a very old 286 version of Xenix running in a VM, I concluded that it was probably incompatible with any 386 and later processor. Recently I revisited this issue and examined the problem … Continue reading
Posted in 286, Intel, Xenix
32 Comments