A "register" is just a [core] memory word. ("The PDP-1 uses an 18-bit word size and has 4096 words as standard main memory", https://en.wikipedia.org/wiki/PDP-

A "register" is just a [core] memory word. ("The PDP-1 uses an 18-bit word size and has 4096 words as standard main memory", https://en.wikipedia.org/wiki/PDP-1 https://en.wikipedia.org/wiki/PDP-1). Terminology changed since then. I like how the assembly source code is small enough to include at the end of the manual. A bit of slogging finds you the source code and a pdp-1 assembler, enough to run it on simh or MESS, but even though there's a online PDP-1 emulator running SpaceWar!, I wasn't able to find a way to run Lisp 1 online. * http://www.softwarepreservation.org/projects/LISP/interlisp_family/ http://www.softwarepreservation.org/projects/LISP/interlisp_... * http://simh.trailing-edge.com/kits/lispswre.zip http://simh.trailing-edge.com/kits/lispswre.zip