Re: DECs funny numbering sytem
DEC's PDP models were numbered in chronological order, with no indication of the different architectural families. So the PDP-1, 4, 7, 9 and 15 were 18-bit machines, the PDP-5, 8, 12 and 14 were 12-bit, and the PDP-3, 6 and 10 were 36-bit. The PDP-11 was something of an oddity being 16-bit.