Category Archives: Microsoft

The A20-Gate Fallout

A recent post explored the motivation (i.e. backwards compatibility) to implement the A20 gate in the IBM PC/AT. To recap, the problem IBM solved was the fact that 1MB address wrap-around was an inherent feature of the Intel 8086/8088 CPU, … Continue reading

Posted in IBM, Microsoft, PC architecture, PC history | 59 Comments

EXEPACK and the A20-Gate

In 1991, DOS 5.0 brought about what’s perhaps the most common manifestation of A20 control trouble… Packed file is corrupt Microsoft published a┬áKB article about this infamous error, but its author clearly did not understand the true cause of the … Continue reading

Posted in Bugs, Microsoft, PC history | 14 Comments

The A20-Gate: It Wasn’t WordStar

Although WordStar was long suspected to be the reason (or at least one of the major reasons) for implementing the A20 gate hardware on the PC/AT and all the associated problems later on, it is now all but certain that … Continue reading

Posted in 286, IBM, Microsoft, PC history, WordStar | 36 Comments

Microsoft Editor

(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 | 17 Comments

Pascal Out Of Memory

Suppose you want to run the original 1981 vintage IBM Pascal 1.0 (supplied by Microsoft) on a PC that is less than 30 years old. Upon execution, PAS1.EXE may well fail with the following error: Error: Compiler Out Of Memory … Continue reading

Posted in Bugs, Corrections, IBM, Microsoft, PC history | 40 Comments

Wanted: Console Text Editor for Windows

(This is a guest post by Antoni Sawicki aka Tenox) Since 2012 or so Microsoft is pushing concept of running Windows Server headless without GUI and administering everything through PowerShell. I remember sitting through countless TechEd / Ignite sessions year … Continue reading

Posted in Editors, Microsoft, NT, Watcom | 15 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

MS KB Articles

A recent blog post over at explores some of the mysteries surrounding information that at one point or another was published as a Microsoft KnowledgeBase article (or a KB article for short). It’s not entirely clear where the KB … Continue reading

Posted in Documentation, Microsoft, PC history | 17 Comments

PC DOS 1.0, But Not Quite

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 | 43 Comments