Exactly. Recently, when Wirth couldn't find an OS with a device driver for his favourite mouse, he built his own hw + OS + userland combination so he could keep using the mouse he got as a souvenir of his Xerox sabbatical. (I believe the monitor and keyboard were off-the-shelf.)

He's not primarily a programmer, but a computer engineer. It wasn't his first computer system, and may not even be his last. The mouse stays the same size, but the computers themselves have shrunk dramatically over the years. Maybe when he turns 90 he'll ship-in-a-bottle build a computer inside his favourite mouse?

> Maybe when he's 90 he'll ship-in-a-bottle build a computer inside his favourite mouse?

Ha wouldn't be shocked. Apparently some mice already have ARM processors inside, why not take it a bit further.

They may prefer it, but why should I?

Or they may never have thought about running on a different device. Why should I do the work to do it?

This was not done with the idea of portability, maintainability, or even good engineering practice.

Why not just say that then