page_title: PDP-1
section_title: Peripherals
hierarchical_section_title: PDP-1 / Peripherals
caption_attribution_description: English: PDP-1 computer Русский: Компьютер PDP-1
context_page_description: The PDP-1 is the first computer in Digital Equipment Corporation's PDP series and was first produced in 1959. It is famous for being the computer most important in the creation of hacker culture at MIT, BBN and elsewhere. The PDP-1 is the original hardware for playing history's first game on a minicomputer, Steve Russell's Spacewar!
context_section_description: The PDP-1 uses punched paper tape as its primary storage medium. Unlike punched card decks, which could be sorted and re-ordered, paper tape is difficult to physically edit. This inspired the creation of text-editing programs such as Expensive Typewriter and TECO. Because it is equipped with online and offline printers that were based on IBM electric typewriter mechanisms, it is capable of what, in 1980s terminology, would be called "letter-quality printing" and therefore inspired TJ-2, arguably the first word processor.
  The console typewriter is the product of a company named Soroban Engineering. It uses an IBM Model B Electric typewriter mechanism, modified by the addition of switches to detect keypresses, and solenoids to activate the typebars. It uses a traditional typebar mechanism, not the "golfball" IBM Selectric typewriter mechanism, which was not introduced until the next year. Lettercase is selected by raising and lowering the massive type basket. The Soroban is equipped with a two-color inked ribbon (red and black), and the interface allows color selection. Programs commonly use color-coding to distinguish user input from machine responses. The Soroban mechanism is unreliable and prone to jamming, particularly when shifting case or changing ribbon color.
  Offline devices are typically Friden Flexowriters that have been specially built to operate with the FIO-DEC character coding used by the PDP-1. Like the console typewriter, these are built around a typing mechanism that is mechanically the same as an IBM Electric typewriter. However, Flexowriters are highly reliable and were often used for long unattended printing sessions. Flexowriters have electromechanical paper tape punches and readers which operate synchronously with the typewriter mechanism. Typing rates are about ten characters per second. A typical PDP-1 operating procedure is to output text to punched paper tape using the PDP-1's "high speed" (60-character-per-second) Teletype model BRPE punch, then to hand carry the tape to a Flexowriter for offline printing.
  In later years, DECtape drives were added to some PDP-1 systems, as a more convenient method of backing up programs and data, and to enable early time-sharing.  This latter application usually requires a secondary storage medium for swapping programs and data in and out of core memory, without requiring manual intervention.  For this purpose, DECtapes are far superior to paper tapes, in terms of reliability, durability, and speed.  Early hard disks were expensive and notoriously unreliable;  if available and working, they are used primarily for speed of swapping, and not for permanent file storage.
caption: PDP-1 Type 30 point-mode CRT display and console typewriter, with processor frame in background
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