How Bill Gates, the Altair 8800 and BASIC propelled me into the PC revolution

The Altair 8800, the first commercially successful personal computing device.

Boston Globe/Getty Images

Have I told you the story about Bill Gates and me in those early days of personal computing?

To be clear: Bill Gates is older than I am. In 1975, as Bill was leaving Harvard to start Microsoft, I had just skipped my last year of high school and started college. I was the youngest student in engineering school that first year -- the same year Bill and I were using the same computer technology: the Altair 8800 and the Digital Equipment PDP-10.

My high school computing experience -- like Bill's -- was formative. However, I never wanted to be a computer scientist. I wanted to build nuclear reactors. 

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In high school, I was still grappling with being a teenager, convincing the adults that I needed to be in engineering school instead of coasting through senior year, trying to persuade Amy Katz to let me buy her ice cream, failing the high school's mandatory typing class, and wondering how I was supposed to deal with the teletype that was initially the sole component of our computer "lab."

From nukes to PCs

Here's what broke me and sent me on this wacky course I call my career. I sat down at that teletype and pressed the Return key. It responded with "READY."

You need to put this in a 1970s perspective. Today, we talk to ChatGPT and get Star Trek computer-like responses. But back then, machines were not interactive. So when that teletype responded with "READY," it rewired my brain forever. It was interactive. It was different. It changed everything about what my relationship with machines could be.

But let's take a moment and return to when Gates and Paul Allen started Microsoft. I mentioned the Altair 8800 because that machine was the first commercially successful personal computing device. Before Ed Roberts started MITS (the company that made the Altair), computers were big -- room-scale, gymnasium-size big. The idea of a personal computer was pure science fiction.

Then, in 1974, Roberts introduced the Altair 8800 through an article in Popular Electronics. Roberts and the magazine editors were offering regular people the opportunity to own and use a computer.

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As the story goes, the Altair didn't come with any software. Geeks could tinker with it and toggle programs on the front panel, but there wasn't any real programming language beyond the Intel 8080 assembly language. Gates and Allen saw the opportunity to produce a BASIC interpreter for the machine and pitched it to Roberts.

According to legend, no code had been written when they originally spoke to MITS about their programming language. It was only once they were invited to show the code to Roberts and his team that Gates and Allen got to coding.

The full story of that experience is chronicled in a 50th Anniversary blog post by Gates published this week. I recommend you read it. I mentioned our mutual use of the DEC PDP-10 computer. Well, Gates and Allen wrote the original basic on Harvard's PDP-10, before bringing it down to Albuquerque-based MITS to demonstrate.

Building my own Altair 8800

Until I built my first Altair 8800, I lived in my engineering school's computer center, typing code into our PDP-10 until the wee hours of the night (and often through the night and into the next day).

I couldn't afford the $1,500 or so that the original fully assembled Altair 8800 cost back then, which would be more than $7,000 now. So I waited a few years until people started to get tired of their Altairs or failed to make them work. I bought parts at swap meets at very steep discounts and horse-traded my way to having enough components to build a full machine.

CNET: Bill Gates publishes original Microsoft source code in a blog post

Over the course of a summer at my parent's home, I built the machine, hand-soldered the hundreds of wires to the front panel, and even toggled in a bootloader that enabled BASIC to be loaded into the machine.

After about a week toggling all that code in, one byte at a time, my Dad decided to work on a circuit somewhere in the house and shut off the power to my room. I had to spend another week doing it all over again, but I eventually got a working computer.

We also need to put Microsoft's BASIC language into perspective. Programming languages are often described as "higher-level languages." That's because the native language of the machine, called machine language or assembly language, is both very tied to a given machine's architecture and very granular. You don't add two numbers together. You move bits around -- bit-by-bit -- until some set of combinatorial operations results in a sum.

Higher-level languages are written with more functionality per statement. The code is compiled (converted all at once) or interpreted (converted statement by statement) into something the machine can understand.

Gates and Allen first wrote a program on the PDP-10 that emulated the machine code of the Intel 8080; then they wrote an interpreter that translated BASIC code dynamically and interactively into 8080 code the processor could run.

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Writing in BASIC was fun, creative, and empowering. Writing in machine code or its related assembler language was tedious and incredibly time-consuming. So, without a BASIC programming language for the Altair (and later for Apple machines), the personal computer industry wouldn't have taken off. Individual computers would have been too painful to use and likely would have seen service only in labs and industrial uses.

The brilliance of BASIC

Also, don't discount the feat of coder brilliance that Allen and Gates pulled off. It was impressive as hell to code an 8080 emulator and an entire BASIC interpreter in those days. If you look through that first code that they produced, you can see the care they took to make it both functional and maintainable.

Yes, I said, "If you look through that first code." That's because, concurrent with Bill's blog entry celebrating 50 years, he's also releasing a PDF of that first BASIC source code. I haven't read through all 157 pages of tractor-feed fan-fold paper, but I have had the pleasure of scanning several pages. This is some seriously old-school, hard-core stuff right there.

Young Bill and Paul had some serious chops.

I met Bill only once. I had dinner with him about a dozen years after Microsoft was formed. He was well on his way to making his first billion, and I had just started my first software company. MS-DOS was dominant on PCs, and Windows was still mostly a concept prototype.

Also: Dell turns 40: How a teenager transformed $1,000 worth of PC parts into a tech giant

We met because he was the guest speaker -- and I was on the board of directors -- for Silicon Valley's Software Entrepreneurs' Forum. One of the perks of board membership was sharing the head table with our guest speakers each month. I made it my business to sit right across from each of the luminaries at each event. Not only did I get to meet them, I got to talk to them and learn from them.

Bill's unexpected advice

I asked Bill what advice he had for a newly minted software startup founder. I expected some wisdom about software lifecycles or hiring good engineers. Instead, he told me to mind my cash flow. "Cash flow is everything," he said. Yes, the advice I got from the guy who would become the richest man in the world (at least until recently) was about minding my cash flow.

I took that lesson to heart and my businesses did pretty well. Not millionaire or billionaire well, but they did well enough to support my family and those of the people who worked for me.

Thinking back on that BASIC implementation and the Bill and Paul of 50 years ago, it's clear that my career as a whole benefited from their work. While no longer a popular language, BASIC was easy to learn and use. It's fallen out of favor because it's not that easy to maintain and doesn't scale as well as modern languages. But it was a gateway drug for a lot of early PC programmers.

Also: Dell turns 40: How a teenager transformed $1,000 worth of PC parts into a tech giant

When I was in engineering school, I used big iron. But it was PCs that sparked my imagination. It turned out I was very good at operating system design, language design, and overall computer science. Unfortunately, despite my desire to go into nuclear engineering, I was far from a star nuke student.

By sophomore year, I'd used up all the college's computing curricula and started taking (and then teaching) graduate school computer science courses. I was still barely making it through the first few physics classes required for nuclear engineering.

My academic advisor, who knew of my Altair build and my affinity for these new personal computers, strongly advocated I move out of the nuclear engineering program and fully embrace computer science. I don't know if I'd have had that affinity for PCs if Microsoft's BASIC didn't run on them. I never liked assembly language programming.

I wonder whether I would have been stuck underground, getting my body parts irradiated, and living on the edge of civilization as a barely adequate nuclear engineer had I not developed an affinity for PCs -- an affinity that BASIC made possible in my very early formative years.

As one does, I eventually moved on to other languages -- and, in fact, to many other languages. But BASIC, and particularly that BASIC for that Altair 8800 machine, still holds a special place in my heart.

Also: The Mac turns 40: How Apple's rebel PC almost failed again and again

So, on behalf of all the middle-aged programming geeks worldwide who cut their teeth on Microsoft BASIC, I raise my cup of Kirkland Pacific Bold to Bill Gates, Paul Allen, Ed Roberts, and all the early ones -- yes, that includes Steve and Steve from Apple -- who brought personal computing to the rest of us.

What about you? Did you get your start in computing with BASIC, or maybe even on an Altair or PDP-10? Were you around when Microsoft first entered the scene -- or did you come in later and discover the magic of early personal computing secondhand? How did you first get hooked on programming, and what role did Microsoft's early software play, if any? Let us know in the comments below.

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