Category Archives: PC history

XMVM Surgery

Last week I was prompted to take a look at the Intel Code Builder compiler from 1991, a 32-bit compiler targeting 386 extended DOS and shipping with its own DOS extender. It is what one might call an extremely obscure … Continue reading

Posted in 386, Development, Intel, PC history, Software Hacks | 10 Comments

Another Trip to Drive Geometry Hell

Recently I took another close look at the IDE.DSK driver in NetWare 3.12. Among other things, I wanted to know how it differs from ISADISK.DSK. On some systems, the two drivers are interchangeable and either will work. But there are … Continue reading

Posted in IDE, NetWare, PC history | 8 Comments

Another Myth Busted

More than once I came across a story of a heroic MicroPro programmer who in an all-night session managed to port WordStar from CP/M to DOS by patching a single byte. This is how the legend was retold by Joel … Continue reading

Posted in CP/M, DOS, PC history, WordStar | 5 Comments

Unidentified PC DOS 1.1 Boot Sector Junk Identified

Anyone trying to disassemble the PC DOS 1.1 boot sector soon notices that at offsets 1A3h through 1BEh there is a byte sequence that just does not belong. It appears to be a fragment of code, but it has no … Continue reading

Posted in Development, DOS, PC history | 23 Comments

First Dual-Channel IDE?

The OS/2 Museum recently came into possession of what may be the first adapter with support for two IDE channels… sort of: The adapter was made by Plus Development Corporation, a subsidiary of the disk maker Quantum. This particular specimen … Continue reading

Posted in IDE, PC hardware, PC history, Quantum | 29 Comments

The Secret History of ATAPI

The other day I asked myself a seemingly trivial question: What was the first ATAPI CD-ROM drive and when was it available? Given that ATAPI was a major technology which instantly obsoleted all proprietary CD-ROM interfaces and made SCSI much … Continue reading

Posted in CD-ROM, PC history, Standards, Undocumented | 53 Comments

Looking for High Sierra

Some time ago, I thought it would be useful to understand exactly what is the difference between CD-ROMs recorded in the old High Sierra format versus the ISO 9660 standard. This was in part spurred by the fact that I … Continue reading

Posted in CD-ROM, Documentation, PC history | 23 Comments

Deeper Into ATA History

While looking for something completely unrelated (namely the Rock Ridge extensions to ISO 9660), I came across a cache of old X3T9 committee documents from 1990. In retrospect I’m a little surprised that I hadn’t found these earlier, since the … Continue reading

Posted in IDE, PC history, Standards | 17 Comments

Weird Tales

While researching various aspects of the history of computing, sometimes I come across what can best be described as “weird tales” — unsourced claims that sound interesting but are either provably wrong or there’s no evidence to support them. In … Continue reading

Posted in IBM, Microsoft, PC history, PC press | 22 Comments

DOS 2.11 From Scratch

Warning: Long post! After having good luck with rebuilding core PC DOS 1.1 from source code, I thought I’d do the same with the DOS 2.11 source code released by the CHM. What follows is largely a collection of notes … Continue reading

Posted in Development, DOS, Microsoft, PC history | 26 Comments