Monthly Archives: March 2017

There’s More to the 286 XENIX Story

It turns out that there is a rather interesting story behind the 286 XENIX incompatibility with 386 and later processors. Here’s roughly what happened in chronological order. In 1982, Intel released the iAPX 286 processor, later known as the 80286 or simply 286. This … Continue reading

Posted in 286, 386, Intel, Microsoft | 29 Comments

PCI Corner Case

Last weekend I had the pleasure of debugging a curious case of older PCI configuration code (circa 2005) failing on newer (post-2010) hardware. The code was well tested on many 1990s and 2000s PCs (and some non-PCs) with PCI/AGP/PCIe and never … Continue reading

Posted in Bugs, Intel, PCI | 1 Comment

IBM XENIX: Two Steps Forward

There are reasons to revisit an old topic. Very old, considering that IBM Xenix 1.0 was released in 1984, well over 30 years ago. To recap, this version of Xenix is unique in that it runs only on 286 processors. It … Continue reading

Posted in 286, IBM, VirtualBox, Xenix | 7 Comments

Tales From the Xenix Crypt

What does Xenix have to do with the Enigma machine? Perhaps surprisingly, there is a clear connection… When reconstructing 386 Xenix 2.2.3, the libmdep.a library proved to be a particularly tough nut to crack. That is because it’s one of … Continue reading

Posted in SCO, Software Hacks, Xenix | 7 Comments

What a Coincidence

Timeline: Mid-1988: SCO 386 Xenix 2.2.3 is released 1996 (probably): Someone dumps the 386 Xenix 2.2.3 disks, but enough sectors are missing that the OS is impossible to install January 3rd, 2013: OS/2 Museum posts about the damaged Xenix dump February … Continue reading

Posted in PC history, Xenix | 1 Comment

Oldest Surviving 386 PC OS?

Four years ago, the Xenix 2.2.3 mystery cropped up (twice). The issue has been revisited and thanks to Michael Casadevall, an enthusiastic reader, came to a happy conclusion: 386 Xenix version 2.2.3 was finalized in late June 1988 (the newest … Continue reading

Posted in 386, Microsoft, SCO, UNIX, Xenix | 21 Comments

More Data on CF to IDE to SCSI

To get a better picture of the performance of the CF to IDE to SCSI solution, I moved the Adaptec 1542C into one of my favorite boards, the Alaris Cougar with a classic Intel 486 DX2 OverDrive CPU. For a … Continue reading

Posted in 486, CompactFlash, IDE, Storage | 15 Comments