Category Archives: Compaq

Compaq EXTDISK.SYS

Posted on April 16, 2025 by Michal Necasek

This is a follow-up to a previous post about the curious driver in Microsoft OS/2 1.21. After initially writing the article, additional information came to light, explaining why the code was there. In summer 1988, Compaq released the Deskpro 386/25, … Continue reading →

Posted in Bugs, Compaq, DOS, PC history, Storage | 32 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

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

Whence IDENTIFY DRIVE?

Posted on June 4, 2021 by Michal Necasek

As most everyone knows, the AT Attachment standard (informally known as IDE) started by literally bolting the previously standalone AT disk controller onto a MFM drive with a ST506 interface and connecting the assembly to the host system with a … Continue reading →

Posted in Compaq, Documentation, IDE, PC hardware, PC history, Storage | 38 Comments

Breaking Into ASOS

Posted on August 1, 2020 by Michal Necasek

The OS/2 Museum recently acquired a Quantum Bigfoot TS hard disk in mint condition. The Bigfoot drives, as some readers may remember, were rather oddball late-1990s 5.25″ IDE drives that were cheap, slow, and relatively big. There was a sticker … Continue reading →

Posted in Compaq, PC history, SCO | 4 Comments

Well Hello

Posted on July 14, 2020 by Michal Necasek

So after some furious disassembling, assembling, and linking, things got this far: It took longer than it ought to have because although IDA is great, I couldn’t figure out how to make it work with GW-BASIC’s bizarre segment usage. The … Continue reading →

Posted in Compaq, Microsoft, PC history, Source code | 7 Comments

Deskpro 386 at 30

Posted on September 26, 2016 by Michal Necasek

30 years ago, in September 1986, Compaq announced the Deskpro 386, a PC as revolutionary as it was conservative. Compaq decided to forge its own path and not wait for IBM to introduce a 386-based PC. At the same time, Compaq … Continue reading →

Posted in 386, Compaq, IBM, PC history, PC press | 24 Comments

Original CEMM Unearthed

Posted on November 5, 2014 by Michal Necasek

An important fragment of PC history was unearthed a few days ago: An image of a Compaq Deskpro 386 supplemental disk from August 1986, containing among other things CEMM.EXE, Compaq’s original expanded memory emulator shipped with the Deskpro 386. The … Continue reading →

Posted in 386, Compaq, DOS | 28 Comments