Category Archives: PC history

Tarbell to Cromemco

While playing around with old versions of 86-DOS, I came across a disk image of 86-DOS 1.14. I ran the older 86-DOS versions in the SIMH simulator which can emulate the Cromemco disk controller supported by 86-DOS. Unfortunately the 86-DOS … Continue reading

Posted in Development, DOS, PC history | 16 Comments

86-DOS Revisited

At the end of December 2023, several disk images of very old versions of Seattle Computer Products 86-DOS unexpectedly turned up. This includes previously unseen releases of 86-DOS version 0.11 and 0.34 (going by the version number in the 86-DOS … Continue reading

Posted in DOS, PC history | 24 Comments

VDS: Borne out of Necessity

In July 1990, Microsoft released a specification for Virtual DMA Services, or VDS. This happened soon after the release of Windows 3.0, one of the first (though not the first) providers of VDS. The VDS specification was designed for writers … Continue reading

Posted in 386, Documentation, Microsoft, PC history, Windows | 8 Comments

First ROM Shadowing

The other day I was asked an interesting question: What was the first BIOS with support for ROM shadowing? In the 1990s, ROM shadowing was common, at first as a pure performance enhancement and later as a functional requirement; newer … Continue reading

Posted in C&T, Compaq, IBM, PC architecture, PC history | 55 Comments

Windows 3.x VDDVGA

While working on my Windows 3.x display driver, I ran into a vexing problem. In Windows 3.1 running in Enhanced 386 mode, I could start a DOS session and switch it to a window. But an attempt to set a … Continue reading

Posted in 386, Development, Documentation, Graphics, PC history, Windows | 52 Comments

Learn Something Old Every Day, Part VII: 8087 Intricacies

The other day I investigated a report that a C runtime library modification causes programs to hang on a classic IBM 5150 PC with no math coprocessor. The runtime originally contained two separate routines, one to detect the presence of … Continue reading

Posted in 8086/8088, Development, IBM, Intel, PC history, x87 | 10 Comments

PC Disk Sector Sizes and Booting

Everyone knows that the IBM PC established 512-byte sectors on floppies and hard disks as the standard, which survived for several decades until the advent of “native” 4K-sector drives. Of course what “everyone knows” is not necessarily the whole story. … Continue reading

Posted in BIOS, DOS, IBM, PC history, Storage | 15 Comments

Slovenian OS/2 Warp 4

This is a guest post written by Marko Ć tamcar from the Slovenian Computer Museum in Ljubljana. Additional context and commentary from the OS/2 Museum can be found at the end of the article. Slovenia being a tiny country with a … Continue reading

Posted in IBM, OS/2, PC history | 14 Comments

WordSet: Stolen Without Compensation

A kind reader from a land formerly beyond the Iron Curtain recently supplied the OS/2 Museum with a curious word processor that calls itself WordSet. The files unfortunately lost their original timestamps quite some time ago, but it is apparent … Continue reading

Posted in Editors, I18N, PC history, WordStar | 29 Comments

Compaq EGA Technical Reference Guide

A rater nice Compaq EGA Tech Ref recently turned up on archive.org, under the title COMPAQ Enhanced Color Graphics Board Technical Reference Guide. It’s from December 1986, relatively late in EGA’s life (given that it was about to be obsoleted … Continue reading

Posted in Compaq, Documentation, PC history | Leave a comment