The last post about the Nothing Phone not buffering its button presses reminded me of something.

Here’s IBM Selectric, a 1961 typewriter:

Past decades get compressed into a singular point in time, so we might all think of Selectric as “yet another old typewriter,” and I definitely did before learning about it. But the Selectric came 80 years after the first typewriters, and it packed so much user-benefitting innovation it really was an iPhone of its time. (Alas, I don’t believe there was a matching “are you getting it?!” keynote.)

Selectric was, honestly, a triumph of engineering. It popularized swappable typewriter fonts, showcased good industrial design, enabled jam-free typing, and even invented – although that came a decade after its introduction – an actual destructive Backspace. Crucially, on day one, its typing experience was so fantastic that many of the keys on keyboards we’re using 60 years later are still in the same place Selectric put them.

What’s even more impressive? Selectric was purely electromechanical. It had no software, no chips, and no electronics. Everything it has accomplished was expressed in the mechanical language of steel, grease, links, and levers.

Here’s one problem that’s trivial in software, but hard in hardware: How do you prevent people from pressing two keys at the same time?

This is a thing that plagued typewriters since day one, and IBM’s engineers came up with a smart solution: each key was connected to a bar (interposer), each bar had a little protruding notch (lug), and that notch would smoothly dip into a little horizontal row of steel balls (selector compensator tube).

The balls had just enough wiggle room for one notch, so if you tried to press a second key at the same time, the balls would now be packed tight, there would be no room to accommodate the second notch, and the key press would be blocked.

I thought that was really clever, but it was even more clever than that. If you read my essay, you know it starts with the very notion that fingers overlap: as one is going up, often another one is already pressing down. If you were to block any second press before the first press was completely done, you wouldn’t be able to type very fast – and Selectric was meant to be a professional typing tool.

Here’s where the choice of the carefully sized and arranged steel balls came into play. In practice, the second press was not completely blocked. The lug was able to slide just a little bit in between the adjacent steel balls. It was a half press – or, effectively, a half-character buffer. It was all fine-tuned just enough to not impede overlapping typing, while still offering protection from two keys at the same time.

Now, if Selectric did this, in a universe where creating even a half-character buffer meant a little row of carefully machined steel balls, and added weight, and anticipating future wear and tear, and multiple pages in the maintenance manuals… what’s your excuse?