Multics Intro Course (1978)

Also see https://ban.ai/ and https://ban.ai/Multics/doc/

Specially worthwhile to read is how Multics security model compares to UNIX.

https://multicians.org/b2.html

And how much safer PL/I was, even when compared against C17.

9 * 4 = 36-bit word.

Yes and it wasn’t alone, I’ve programmed on several machines that didn’t have 8-bit organization. The DEC PDP-9 and some others had 18 bit words and the big CDC 6600 series had 60 bit words with 10 chars per word, not exactly Unicode.

It makes a lot of sense if you write octal instead of hexadecimal.

It was a 36-bit machine that supported both 6 and 9-bit bytes, though since Multics was case sensitive (the first case-sensitive/lowercase OS I'd ever used) IIRC the sixbit mode was not used by Multics.

The most popular 36-bit hardware, the PDP-6/PDP-10/DEC-20 family, supported addressable bytes from 1-63 bits in width. Doesn't it seem odd that C defaults to octal? Because of the legacy of earlier machines on which octal was more natural, C & Unix picked it up too, despite being developed on the PDP-7 and later PDP-11.

I think the 8-but byte might have started out as an IBMism.