Category Archives: DOS

Why Does Windows Really Use Backslash as Path Separator?

Posted on May 24, 2019 by Michal Necasek

More or less anyone using modern PCs has to wonder: Why does Windows use backslash as a path separator when the rest of the world uses forward slash? The clear intermediate answer is “because DOS and OS/2 used backslash”. Both … Continue reading →

Posted in DEC, DOS, IBM, Microsoft, PC history | 42 Comments

A Word on the CALL 5 Spell

Posted on May 26, 2018 by Michal Necasek

After years of searching for some reasonably widespread DOS application which used the CP/M-style CALL 5 interface and coming up with absolutely nothing, Jeff Parsons of pcjs.org found one: None other than Microsoft Word, specifically the spell checker in the … Continue reading →

Posted in DOS, Microsoft, PC history | 10 Comments

Microsoft Editor

Posted on March 11, 2018 by tenox

(This is a guest post by Antoni Sawicki aka Tenox) In a recent blog post I lamented the lack of a good console/cmd/PowerShell text editor for Windows. During the process I made a rather interesting discovery, that in a fact … Continue reading →

Posted in Development, DOS, Editors, Microsoft, NT, OS/2, Source code, Uncategorized | 23 Comments

WordStar Again

Posted on January 26, 2018 by Michal Necasek

While trying to work on my DOS 5.0 article, I looked at DOS 5.0 build 224 from June 1990, which is the oldest surviving beta of DOS 5.0. And the README contains the following intriguing text, which reminded me of … Continue reading →

Posted in DOS, PC history, WordStar | 74 Comments

DOS 5: TMI

Posted on January 19, 2018 by Michal Necasek

For several years now I’ve been trying to continue the DOS history series and write (or rather finish) a DOS 5 page. While tracing the history of DOS 1.0 or 2.0 is quite difficult and the amount of source material … Continue reading →

Posted in DOS, PC history, Random Thoughts | 14 Comments

How to Void Your Valuable Warranty

Posted on January 12, 2018 by Michal Necasek

Try installing Quick Pascal 1.0 on DR DOS 3.40: What is going on there? It’s a long story… In 1988, Microsoft became increasingly worried by a new upstart OS from an old rival, DR DOS. Over the years, Digital Research … Continue reading →

Posted in Digital Research, DOS, Microsoft | 43 Comments

There’s Another Possibility

Posted on January 2, 2018 by Michal Necasek

Four years ago we pondered why on Earth a DOS floppy boot sector might start with 69h, supposedly a “direct jump” opcode. Which is the IMUL instruction on 80186 and later, and not documented on 8086. In the meantime, it … Continue reading →

Posted in DOS, Floppies | 57 Comments

PC-MOS/386 Source Code

Posted on October 5, 2017 by Michal Necasek

I missed this when it was initially announced. The source code for PC-MOS/386 version 5.01 is now available on github under the GPLv3 license. It requires the user to supply Borland C++ 3.1 in order to build, but there are … Continue reading →

Posted in 386, DOS, Source code | 8 Comments

PC DOS 1.0, But Not Quite

Posted on May 26, 2017 by Michal Necasek

Last week a most interesting image of a 160K disk arrived at the OS/2 Museum. The files on the disk image are rather old. When the disk boots up (not trivial, see below), the following message appears: Astute readers will … Continue reading →

Posted in DOS, IBM, Microsoft, PC history, Pre-release | 47 Comments

Booting Is Hard

Posted on February 23, 2017 by Michal Necasek

So I had this brilliant idea of using SCSI drives with old 286/386/486 boards which have old BIOSes that can’t handle IDE drives bigger than 500-ish megabytes. The SCSI HBA is the first one I happened to grab, an Adaptec 1542C … Continue reading →

Posted in 386, BIOS, CompactFlash, DOS, SCSI | 21 Comments