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Comment by Torwald | Hacker News Reader

> By porting Unix to the PDP-11 in 1970, the group ensured Unix would live on into the future.

I have a question about that. Why would they do this?

What was so valuable in these few lines of (mostly proprietary) code, that you would make the effort to port instead of just writing from scratch on the new machine?

If you take a look at what came later, a lot of much more substantial software packages were made by a single bedroom coder in his spare time.

Why port? It couldn't be to save effort? (At least the conceptual level of things would remain the same if you start from scratch.)

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The first PDP-11 Unix was written in assembly, and was thus a from-scratch rewrite of PDP-7 Unix (also in assembly, for a very different machine). The rewrite into an early version of C came later, done initially for the same reasons you'd prefer C to assembly in, say embedded systems (maintainability) -- and the idea of using the C code as the basis for a port came a few years after that.

See https://en.wikipedia.org/wiki/History_of_Unix

They ported because there was a user base that liked the commends and environment and wanted to keep using it. It was a rewrite from scratch to the same design spec.

About 1970 the first minicomputers were being applied to operations, administration and maintenance functions in the Bell System. The PDP-7 was too expensive and the PDP-8 was too limited to compete favorably with others. The PDP-11 was applied widely and if the Unix OS was to be used by the development groups instead of the DEC operating systems, it had to be ported.

The port wasn't motivated by the development groups. It was sold to management as a word processing / typesetting system.

I vividly remember my first encounter with Unix, in an ACM journal archive at the local university library as a teenager in the late '70s, utterly astonished to find lower-case computer commands and prompts.

True, the development groups weren't too keen on Unix. They wanted to choose the minicomputer and operating system from those commercially available and get on with developing applications without the risks and effort of using an unproven operating system. But Research always wanted to demonstrate that they were contributing to the company, so eventually Unix had to be adopted.

Use by development groups for Western Electric products was different from the in-house Unix systems run by the Bell Labs data center that were used as time shared systems for email, general computing, and document production using nroff and memo macros. Moving away from all upper case made line printers less efficient, but about that time laser phototypesetting became available.

The main thing at the time was that mixed-case Teletypes were becoming common.

Their goal was to develop a cross-platform OS - so porting was kind of the whole point. Making code and systems portable between architectures was a research topic they wanted to prove out and learn from.

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