Category Archives: Storage

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

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

Drive Price Mystery

Posted on August 17, 2021 by Michal Necasek

While digging into the history of DoubleSpace and DriveSpace, I came across a handy article about the rocky relationship between Stac Electronics and Microsoft. Only I was distracted by the bold claim (certainly claimed in very bold letters) that a … Continue reading →

Posted in PC history, Storage | 16 Comments

How Not to Erase Data

Posted on August 16, 2021 by Michal Necasek

From past blog posts it is fairly obvious that the OS/2 Museum occasionally purchases used hard disks. Most of the time, the disks are either completely erased (overwritten with zeros) or don’t have anything very interesting on them. But sometimes … Continue reading →

Posted in DOS, PC hardware, Storage | 17 Comments

IDENTIFY Ancient DRIVE

Posted on July 22, 2021 by Michal Necasek

This article will attempt to collect IDENTIFY DRIVE dumps from antique IDE drives, with running commentary. For the purposes of this list, “antique” is defined as a drive model released in 1990 or earlier, typically with the drive itself also … Continue reading →

Posted in IDE, PC hardware, PC history, Storage | 9 Comments

Learn Something Old Every Day, Part II

Posted on July 17, 2021 by Michal Necasek

The ultimate reason why I pulled out the old Seagate ST-225 drive was because I wanted to try connecting it to the Western Digital WD1003-IWH board that I recently acquired. The WD1003-IWH is a curious evolutionary half-step between ST506 interface … Continue reading →

Posted in IDE, PC hardware, PC history, Storage | 11 Comments

Learn Something Old Every Day

Posted on July 14, 2021 by Michal Necasek

More or less by accident I found myself writing a very basic DOS utility to read data off of an IDE drive. It started out by just issuing the IDENTIFY DRIVE command and capturing the data, but adding the ability … Continue reading →

Posted in Documentation, PC hardware, PC history, Seagate, Storage | 3 Comments

Centaur Close-ups

Posted on July 2, 2021 by Michal Necasek

Readers have expressed interest in seeing what exactly a Western Digital ‘Centaur’ drive looked like. I took a few photos of a WD95044-A drive, the larger capacity (40 MB) and newer variant of the WD Centaur family. Some photos were … Continue reading →

Posted in PC hardware, PC history, Storage, Western Digital | 4 Comments

Can This Conner Talk?

Posted on June 18, 2021 by Michal Necasek

As part of research into the IDENTIFY DRIVE command, the OS/2 Museum acquired two old Conner IDE drives, a CP-342 and a CP-341i. These drives look extremely similar at first glance, and they’re both 40 MB IDE drives, but on … Continue reading →

Posted in Conner, Debugging, Hardware Hacks, Storage | 19 Comments

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 | 36 Comments