A PCjs Retro-Programming Project

BASIC-DOS is on Twitter Project maintained by jeffpar



This is the “history” of the BASIC-DOS, the first version of DOS that might have been created for the IBM PC.

In this alternate timeline, the year is 1980, and we know that in a little over a year, on August 12, 1981, the IBM PC will be introduced, and we really want to make the first PC operating system as compelling and powerful as possible.

So, we have more time to prepare than Microsoft originally did, and we have the benefit of hindsight (or foresight, since it’s 1980).

For example, we know that higher capacity diskettes and hard disks will soon become available, so maybe we can make some early design decisions about the FAT file system that will smooth the way for those improvements.

We also know that people will be looking for ways to be as productive as possible with their PCs, to maximize their investment. Being able to run programs in the background (like TSRs) sounds nice, but perhaps a machine with a 16-bit processor and 20-bit address bus could also run several foreground programs simultaneously, too.

And as we’re designing the DOS command interpreter along with the BASIC interpreter, it becomes clear that a “batch language” with support for “environment variables” is remarkably similar to features that BASIC already provides. Perhaps a “unified” interpreter could eliminate the need for those extra features, allow us to leverage the editing and debugging capabilities of BASIC, and produce a tool more powerful than either interpreter by itself.

At the same time, perhaps we could find ways to make this unified interpreter faster, with support for programs larger than 64K, and support for integers larger than 16-bit – to create programs that take full advantage of this new processor, instead of perpetuating limitations found on other older platforms (eg, 6502 and 8080-based systems).

And what should we call this operating system? DOS-BASIC? BASIC-DOS?

Let’s see what the future holds.

Jeff Parsons
May 17, 2020

Copyright (c) 2020-2021 Jeff Parsons Released under MIT License