Up to 2003, I used a Digital Equipment Corporation PDP-8A from the late 1960’s to perform and calculate results for spectrochemical analysis on metal samples.
The computer was programmed using “Octal” numbers. The program was loaded using punch tape.
That computer ran nearly continuously from 1979 until 2003. It had, as I remember, 16K of memory and had been upgraded to 32K. It filled a cabinet about 2 feet square and 4 feet high.
Upgrading a PDP8 from its native 4K (12-bit words) of core was a big deal, involving massive add-on boxes. It could support, however clunkily, up to eight 4Kword banks, seven of them external to the CPU box.
We bought a rare non-catalog DEC 8K word add-on For our PDP8/L in 1972. It was a 10.5” high box, same size as the CPU. It cost $7000. The box could be populated, IIRC, with two more core stacks for a total add-on of 16K words.
Of course a PDP8 word, being 12 bits, was what we would call a byte and a half.
DEC persisted with word widths that were multiples of 3 bits (i.e., 12, 18, and 36) from its founding in the 50’s up through 1971, when they introduced the 16-bit PDP-11. From then on, it would be all 8-bit byte addressable machines.
So octal was the natural notation system for the early DEC machines. This artifact shows up in Unix and in the C language, which began life on the 18-bit DEC PDP7/9/15 series. It became an annoyance when Unix was ported to the PDP-11, and all subsequent architectures from DEC and others.