Category Archives: PC history

VDS: Borne out of Necessity

Posted on October 5, 2023 by Michal Necasek

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 | 6 Comments

First ROM Shadowing

Posted on April 21, 2023 by Michal Necasek

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

Posted on January 23, 2023 by Michal Necasek

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

Posted on January 23, 2023 by Michal Necasek

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

Posted on October 26, 2022 by Michal Necasek

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

Posted on September 11, 2022 by Michal Necasek

This is a guest post written by Marko Štamcar 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

Posted on June 21, 2022 by Michal Necasek

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

Posted on June 1, 2022 by Michal Necasek

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

IDENTIFY ESDI DRIVE

Posted on May 25, 2022 by Michal Necasek

As previously mentioned on this site, the IDENTIFY DRIVE command in the ATA specification almost certainly first appeared in ESDI controllers supplied to Compaq by Western Digital. Since I have now finally secured a working ESDI hard disk, I could … Continue reading →

Posted in ESDI, IDE, PC hardware, PC history, Western Digital | 19 Comments

1989 Networking: OS/2 NetWare Requester 1.1

Posted on May 7, 2022 by Michal Necasek

When I wrote about the pre-release NetWare Requester for OS/2, the oldest archived officially released NetWare OS/2 Requester was version 1.2 from 1990. In the meantime, version 1.1 of the requester showed up, although I only became aware of that … Continue reading →

Posted in NetWare, Networking, OS/2, PC history, Virtualization | 11 Comments