By the end of 1977, the personal computer revolution was underway.
The Commodore PET, Apple II, and TRS-80 Model I (the 1977 Trinity) were shipping, and each greeted users the same way: a blinking cursor and a BASIC prompt. But code behind that blinking cursor wasn’t the same. Each machine launched with a different BASIC, written by different people, and with very different priorities.
But within just a couple of years, that diversity disappeared.
In this video, I tell the story of how Microsoft BASIC became the de-facto standard, replacing Apple’s Integer BASIC and the TRS-80’s Level I BASIC. And it doing so, it laid the foundation for Microsoft’s rise as the dominant personal computer software company.
The episode follows two parallel stories:
On the Apple II, Steve Wozniak’s Integer BASIC was hand-written and assembled on paper, and entered into ROM by writing hex codes. It was fast, elegant, and perfectly matched to the computer he designed from scratch. But it lacked floating-point math. As Apple pushed toward business users and Wozniak focused his energy on the revolutionary Disk II floppy disk controller, Steve Jobs made a pragmatic decision. He licensed Microsoft’s BASIC with floating point support built-in. That choice solved an immediate problem, but it created a long-term dependency that would come back to haunt Apple.
On the TRS-80, the story was even more dramatic. A missed deadline by an outside contractor forced hardware designer Steve Leininger to scramble, adapting Tiny BASIC and performing what he later called “miracle work” to cram floating-point math, I/O, and system control into just 4K of ROM. It shipped as “Level I BASIC” — with the name itself signaling what was coming next. When the TRS-80 succeeded, Microsoft’s Level II BASIC was activated and became the standard BASIC shipped with new TRS-80s.
So why did Microsoft BASIC win? We explore that in the video linked below:
https://www.youtube.com/watch?v=Lv_XcSsjy6c
As always, I’d love to hear your memories of BASIC in the comments.
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