Author Archives: Michal Necasek

Deeper Into ATA History

Posted on October 14, 2021 by Michal Necasek

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

Posted on October 1, 2021 by Michal Necasek

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

Posted on September 21, 2021 by Michal Necasek

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 | 43 Comments

PC DOS 1.1 From Scratch

Posted on September 10, 2021 by Michal Necasek

A number of years ago, the Computer History Museum together with Microsoft released the source code for MS-DOS 1.25 (very close to PC DOS 1.1) and MS-DOS 2.11. I never did anything with it beyond glancing at the code, in … Continue reading →

Posted in Development, DOS, Microsoft, PC history | 30 Comments

Learn Something Old Every Day, Part III: Why MASM Behaves Oddly

Posted on September 8, 2021 by Michal Necasek

As part of a hobby project, I set out to reconstruct assembly source code that should be built with an old version of MASM and exactly match an existing old binary. In the process I learned how old MASM versions … Continue reading →

Posted in Assembler, Development, LSOED, Microsoft, PC history | 11 Comments

PC-86-DOS

Posted on September 3, 2021 by Michal Necasek

A number of years ago, an 8″ disk containing Seattle Computer Products (SCP) 86-DOS 1.0 was successfully imaged. The newest files on the disk are dated April 30, 1981, making the disk the oldest complete release of what was soon … Continue reading →

Posted in Development, DOS, IBM, PC history | 18 Comments

The Dual-Drive IDE Hell

Posted on August 25, 2021 by Michal Necasek

I have perhaps inaccurate but very strong memories from my PC-building days (in the early to mid-1990s) that one of the most failure-prone and frustrating endeavors was trying to get two IDE drives working together on a single cable as … Continue reading →

Posted in IDE, PC hardware, PC history | 22 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 | 18 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

The IBM PC, 41 Years Ago

Posted on August 10, 2021 by Michal Necasek

No, the OS/2 Museum does not have either a time machine or difficulty doing basic math. As of this writing, it is August 2021 and the IBM PC was announced in August 1981, 40 years ago. But in August 1980, … Continue reading →

Posted in 8086/8088, BIOS, DOS, IBM, Intel, PC hardware, PC history | 69 Comments