Re: [TUHS] [TUHS} PDP-11, Unix, octal?

Probably because the 360 had 8-bit bytes? Unless there's something like the PDP-11 instruction format which makes octal optimal, octal is a pain working with 8-bit bytes; anytime you're looking at the higher bytes in a word, unless you are working through software which will 'interpret' the bytes for you, it's a PITA. The 360 instruction coding doesn't really benefit from octal (well, instructions are in 4 classes, based on the high two bits of the first byte, but past that, hex works better); opcodes are 8 or 16 bits, and register numbers are 4 bits. As to why the 360 had 8-bit bytes, according to "IBM's 360 and Early 370 Systems" (Pugh, Johnson, and Palmer, pp. 148-149), there was a big fight over whether to use 6 or 8, and they finally went with 8 because i) statistics showed that more customer data was numbers, rather than text, and storing decimal numbers in 6-bit bytes was inefficient (BCD does two digits per 8-bit byte), and ii) they were looking forward to handling text with upper- and lower-case. Noel