|
| jonjacky wrote:
| Peter Deutsch finished this when he was 17 years old.
|
| https://en.wikipedia.org/wiki/L._Peter_Deutsch
| lisper wrote:
| Not sure which is more impressive, that, or the fact that this
| Lisp ran in under 4k of RAM.
| phtrivier wrote:
| No idea what the arch of a PDP would be like; but the manual
| mentions 4096 "registers". Would those register actually
| correspond to memory words in a more modern arch ? Was it
| possible in assembly to directly address each of those
| register (without the need for MOV-golfing ?)
| ngvrnd wrote:
| Dunno about the pdp-1, but the pdp-10 series machines
| allowed the registers to be addressed like memory, if I
| recall correctly- the registers were special and faster
| than the rest of memory, but one could put machine code in
| them and run it there. I guess using registers would have
| been tricky in that case though.
| aap_ wrote:
| The pdp-1 has two architectural registers: AC and IO and
| they're not addressable as memory. The PDP-10 has a
| similar internal structure but fetches and stores the
| accumulator from/to memory* for instructions that use it.
|
| * in the PDP-6 it really is external memory, in the later
| models (aka PDP-10) it was moved into the CPU
| djmips wrote:
| https://www.masswerk.at/spacewar/inside/pdp1-instructions.h
| t...
| retrac wrote:
| > Was it possible in assembly to directly address each of
| those register (without the need for MOV-golfing ?
|
| Kind of. 12-bit address field in the instruction. It was an
| accumulator machine; the CPU only had one main register (as
| we use the term today) and all operations were between that
| implicit register and the address specified in memory.
| FullyFunctional wrote:
| 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). 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/interli
| sp_...
|
| * http://simh.trailing-edge.com/kits/lispswre.zip
| djmips wrote:
| Some more info about the PDP-1 asm here.
| https://www.masswerk.at/spacewar/inside/pdp1-instructions.ht...
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