Category Archives: Microsoft

LAN Manager 2.1/2.2 Registration

Posted on December 1, 2021 by Michal Necasek

Anyone who spent a bit of time archiving software distributed on floppies probably knows this situation: There’s only one disk set of a given software release known to exist, and it’s not clean. That is, it’s been previously used to … Continue reading →

Posted in Archiving, Debugging, Microsoft, Software Hacks | 18 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 | 37 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 | 24 Comments

Learn Something Old Every Day, Part III

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, Microsoft, PC history | 11 Comments

DOS SMB Client Performance

Posted on May 20, 2021 by Michal Necasek

Recently I had the need to use several different DOS VMs that all used a SMB network client. Although I did not use networking heavily, I noticed that there are massive differences in performance between the VMs. Copying a circa … Continue reading →

Posted in DOS, IBM, Microsoft, Networking | 15 Comments

Nobody Expects…

Posted on April 14, 2021 by Michal Necasek

…the Spanish Inquisition! Well, that too, but also nobody expects that a bland, run-of-the mill Novell NE2000 NDIS driver would crash/hang just because it runs on 486 or later CPUs. I wanted to try the “basic” DOS redirector shipped with … Continue reading →

Posted in 486, Bugs, Intel, Microsoft | 7 Comments

MS LAN Manager NDDK Anyone?

Posted on April 2, 2021 by Michal Necasek

For R&D purposes, I would very much like to get my hands on the circa 1991 Microsoft LAN Manager Network Device Driver Kit which was meant to support the development of NDIS 2.0 drivers. While it is obvious that some … Continue reading →

Posted in Development, DOS, Microsoft, Networking, OS/2 | 10 Comments

Not MSX, Either

Posted on October 7, 2020 by Michal Necasek

Further examining the mystery of boot sectors supposedly starting with byte value 69h, I considered the possibility that the check could have been added for MSX machines. The MSX platform ticks a lot of boxes: It wasn’t 8086 (but rather … Continue reading →

Posted in IBM, Microsoft, PC history | 15 Comments

Really Atari ST?

Posted on September 21, 2020 by Michal Necasek

This blog has previously examined a very very strange code fragment in the BIOS module of DOS. To recap, when deciding whether a boot sector might have a valid BPB, DOS checks whether the first byte is a relative jump … Continue reading →

Posted in DOS, Microsoft, PC history | 18 Comments