Microsoft open-sources "the earliest DOS source code discovered to date"

I dont think I've ever seen a commit that says "49 years ago". Damn.

I remember when I realized I had been using Microsoft all along through my Commodore 64.

What's interesting is that Microsoft BASIC itself was derived from BASIC-PLUS which itself was derived from Dartmouth BASIC (which evolved into a structured programming language called SBASIC (Structured BASIC). But the popularity of Microsoft BASIC, actually halted the standardisation of SBASIC as an ANSI standard.

https://en.wikipedia.org/wiki/Microsoft_BASIC

The Altair BASIC interpreter was developed by Microsoft founders Paul Allen and Bill Gates using a self-written Intel 8080 emulator running on a PDP-10 minicomputer.[1] The MS dialect is patterned on Digital Equipment Corporation's BASIC-PLUS on the PDP-10, which Gates had used in high school.

https://en.wikipedia.org/wiki/Dartmouth_BASIC

Dartmouth BASIC is the original version of the BASIC programming language. It was designed by two professors at Dartmouth College, John G. Kemeny and Thomas E. Kurtz. With the underlying Dartmouth Time-Sharing System (DTSS), it offered an interactive programming environment to all undergraduates as well as the larger university community.

Dartmouth also introduced a dramatically updated version known as Structured BASIC (or SBASIC) in 1975, which added various structured programming concepts. SBASIC formed the basis of the American National Standards Institute (ANSI) "Standard BASIC" efforts in the early 1980s.

In contrast to the Dartmouth compilers, most other BASICs were written as interpreters. This decision allowed them to run in the limited main memory of early microcomputers. Microsoft's Altair BASIC is one example: it was designed to run in only 4 KB of memory (interestingly, it was delivered on paper tape).

Kemeny became involved in an effort to produce an ANSI standard BASIC in an attempt to bring together the many small variations of the language that had developed through the late 1960s and early 1970s. This effort initially focused on a system known as Minimal BASIC that was similar to earliest versions of Dartmouth BASIC, while later work was aimed at a Full BASIC that was essentially SBASIC with various extensions.

But by the late 1980s, tens of millions of home computers were running some variant of the MS BASIC interpreter. It had become the de facto standard for BASIC, which eventually led to the abandonment of the ANSI SBASIC efforts.

Kemeny and Kurtz, however, decided to continue their efforts to introduce the concepts from SBASIC and the ANSI Standard BASIC efforts. This became True BASIC.

https://en.wikipedia.org/wiki/True_BASIC

There are versions of the True BASIC compiler for MS-DOS, Microsoft Windows, and Classic Mac OS. At one time, versions for TRS-80 Color Computer, Amiga and Atari ST computers were offered, as well as a UNIX command-line compiler.

After several years of inactivity, as of February 2026, the TrueBASIC website is officially closed.

>writing a few thousand lines of assembly was what it took to launch a successful software company.

Yes, but that assembly was not DOS, and it wasn’t easy.

Microsoft purchased the DOS code, they didn’t write it. Of course, they did develop and modify DOS. But that was a clever (and lucky) business deal, not a technological accomplishment.

The real beginning of Microsoft was earlier, with Allen, Gates and Davidoff writing the Altair BASIC interpreter. That was a serious achievement.

They had never seen the computer they were writing that assembly code for. They did not even own any computers. It took them 8 weeks on a university computer they were not supposed to be using for that

“Altair agreed to meet them to possibly buy a BASIC interpreter… Gates and Allen had neither a BASIC interpreter nor even an Altair system on which to develop and test one. However, Allen had written an Intel 8008 emulator that ran on a PDP-10 time-sharing computer. Allen adapted this emulator based on the Altair programmer guide, and they developed and tested the interpreter on Harvard's PDP-10.

The finished interpreter, including its own I/O system and line editor, fit in only four kilobytes of memory, leaving plenty of room for the interpreted program. In preparation for the demo, they stored the finished interpreter on a punched tape that the Altair could read, and Paul Allen flew to Albuquerque to meet with Altair…

While on final approach into the Albuquerque airport, Allen realized that they had forgotten to write a bootloader to read the tape into memory. Writing in 8080 machine language, Allen finished the program before the plane landed. Only when they loaded the program onto an Altair and saw a prompt asking for the system's memory size did Gates and Allen know that their interpreter worked on the Altair hardware.”

https://en.wikipedia.org/wiki/Altair_BASIC

To be fair, i think you needed a cutthroat businessman leading the company. Which i guess is more or less the same today

And for such simple processors and systems no less! No descriptor tables to deal with, no memory management to configure. These days it takes a little processor inside the main processor, just to get things started. Those were golden times.

Replace Assembly with TypeScript/Rust/Go/whatever and as long as the idea is good and useful, same thing applies today.

More than a few people would rather die in poverty than put in the effort today even if you offered to time-machine them back with their finished product.

I'd like to hear more about what works in OCR of dot-matrix fonts.

I've been able to OCR letter-quality printer output to 97% (mostly Os and Xs problems).

But it seems that machine-learning text-recognition is also now biased to reject computer code because it doesn't look like human language.

I've recovered some ancient software I wrote via scanning in listings I found among my dad's papers.

Yet another case where text printed on paper outlived any digital storage.