PiDP-11 (PDP-11)

PDP-11 Overview

The PDP-11 (1970) is a 16-bit minicomputer by DEC. Its clean instruction set influenced the design of many later processors, including the Motorola 68000 and indirectly, the ARM architecture. Unix was first written for the PDP-11.

The PiDP-11 replica by Oscar Vermeulen uses a Raspberry Pi running SIMH.

Octal Modes

PDP-11 assembly uses octal (base-8) notation throughout:

000 = 0       010 = 8       020 = 16
001 = 1       011 = 9       021 = 17
007 = 7       017 = 15      077 = 63

File permissions on early Unix were also octal (carried through to modern Unix).

RT-11

RT-11 is a real-time single-user operating system for the PDP-11:

.DIR            List directory
.TYPE file.ext  Display file
.COPY dst src   Copy file
.DELETE file    Delete file
.RUN program    Run program
.DATE           Show/set date
.TIME           Show time

Lunar Lander (RT-11 BASIC)

Classic Lunar Lander game, playable on RT-11 BASIC:

.R BASIC
READY
OLD LUNAR
READY
RUN
LUNAR LANDER
ENTER INITIAL ALTITUDE IN FEET: 500

VT52/VT100 Terminal Animations

The PDP-11 with a VT terminal supports cursor positioning escape sequences:

ESC[H       Cursor home
ESC[2J      Clear screen
ESC[r;cH    Move to row r, column c
ESC[1m      Bold
ESC[0m      Reset

Demo programs like trek and animated displays use these extensively.