Monthly Archives: January 2018

WordStar Again

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

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 | 12 Comments

About That Warranty…

Readers have been wondering what kind of valuable warranty users of Microsoft’s Quick Pascal 1.0 (and other products) might be voiding by running it on top of DR DOS 3.3x or 3.40. I don’t have the original Quick Pascal 1.0 … Continue reading

Posted in Digital Research, Microsoft, PC history, Undocumented | 16 Comments

How to Void Your Valuable Warranty

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 | 30 Comments

There’s Another Possibility

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 | 46 Comments