Monthly Archives: September 2021

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 | 42 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

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