Editing PDP-1 (section)

==Peripherals==
[[File:PDP-1.jpg|thumb|PDP-1 Type 30 point-mode CRT display and console typewriter, with processor frame in background]]

The PDP-1 uses [[Continuous stationery|fanfold]] punched [[paper tape]] as its primary storage medium.<ref name="NGen23" /> Unlike [[punched card]] decks, which could be sorted and re-ordered, paper tape is tedious to physically edit. This inspired the creation of text-editing programs such as [[Expensive Typewriter]] and [[TECO (text editor)|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 printer|letter-quality printing]]" and therefore inspired [[TJ-2]], arguably the first [[word processor]].

The console typewriter, known as the ''Computeriter'', was provided by [[Soroban Engineering]]. It is an adapted [[IBM Electric typewriter|IBM Model B Electric typewriter]] mechanism, modified by the addition of switches to detect key presses, and [[solenoid]]s to activate the [[Typewriter|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.<ref>{{cite manual |url=http://bitsavers.informatik.uni-stuttgart.de/pdf/soroban/Soroban_Computeriter_Decoder_and_Power_Unit_Adjustment_and_Lubrication_Procedures_Feb1961.pdf |title=Adjustment and lubrication procedures for decoder and power unit of the computeriter |publisher=Soroban |year=1963 |via=Bitsavers}}</ref><ref>{{cite manual |url=https://telcontar.net/KBK/Soroban/docs/Soroban%20Computeriter%20Coder%20Unit%20Technical%20Manual%20%28March%201963%29.pdf |title=Operation and service with illustrates parts breakdown for coder unit models EC and ETC computeriter |publisher=Soroban |date=March 1963 |via=Telcontar.net}}</ref><ref>{{cite web |url=https://telcontar.net/KBK/Soroban/ |title=Soroban Engineering |website=Telcontar.net |date=2024-01-24 |access-date=2024-08-17}}</ref>

Offline devices are typically [[Friden Flexowriter]]s 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]].<ref>{{Cite web |last=Mast |first=Bob |date=1998-11-24 |title=From: Bob Mast |url=http://www.blinkenlights.com/classiccmp/friden/bmast.txt |url-status=live |archive-url=https://web.archive.org/web/20220102231005/http://www.blinkenlights.com/classiccmp/friden/bmast.txt |archive-date=2022-01-02 |access-date=2022-03-22 |website=Blinkenlights Archæological Institute |language=en |quote=The Flexowriter was first manufactured by IBM, during WWII, to be used as an automatic letter writer. After the war several [[IBM]]ers bought the rights and formed Commercial Controls, Inc. They manufactured same in the old [[IBM Selectric typewriter]] building in Rochester NY. In the late fifties, [[Friden, Inc.|Friden]] bought Commercial Controls.}}</ref> 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 disk]]s were expensive and notoriously unreliable;  if available and working, they are used primarily for speed of swapping, and not for permanent file storage.

===Graphics display===
The Type 30 Precision [[CRT display]] is a point plotting display device capable of addressing 1024 by 1024 addressable locations at a rate of 20,000 points per second.<ref name="DECmanual">{{Cite book |url=http://www.bitsavers.org/pdf/dec/pdp1/F15D_PDP1_Handbook_Oct63.pdf |title=PDP-1 Handbook |publisher=[[Digital Equipment Corporation]] |year=1963 |pages=33–36 |access-date=2022-03-22 |archive-url=https://web.archive.org/web/20210828035149/http://www.bitsavers.org/pdf/dec/pdp1/F15D_PDP1_Handbook_Oct63.pdf |archive-date=2021-08-28 |url-status=live |via=[[Computer History Museum#Software|Bitsavers]] |language=en}}</ref> A special "Display One Point On CRT" instruction is used to build up images, which have to be refreshed many times per second.<ref name="DECmanual" /> The CRT, which was originally developed for use in radar, is {{convert|16|in|cm}} in diameter and uses a long-persistence [[Phosphor#Standard phosphor types|P7 phosphor]].<ref name="BickleyVid">{{Cite AV media |url=https://www.youtube.com/watch?v=1EWQYAfuMYw |title=Lyle Bickley explains the PDP-1 (and we play the original Spacewar!) |date=2017-05-02 |last=CuriousMarc |access-date=2018-04-07 |archive-url=https://ghostarchive.org/varchive/youtube/20211211/1EWQYAfuMYw |archive-date=2021-12-11 |url-status=live |via=[[YouTube]]}}{{cbignore}}</ref> A [[light pen]] can be used with the Type 30 to pick points on the display. An optional character generator and hardware for line and curve generation are available.<ref name="DECmanual" />