pdp pdp1 at the computer history museum with steve russell creator of spacewar the large cabinet houses the processor itself the main control panel is just above the desk the paper tape reader is above it metallic and the output of the teletype model brpe paper tape punch above that vertical slot a storage tray for eight fanfold paper tapes is attached to the top panel at the left is the ibm model b typewriter modified by soroban and the type 30 crt display is to the far right the pdp1 programmed data processor1 is the first computer in digital equipment corporations 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 description the pdp1 uses an 18bit word size and has 4096 words as standard main memory equivalent to 9216 eightbit bytes though the system actually uses sixbit bytes upgradable to 700465536000000000065536 words the magnetic core memorys cycle time is 535 microseconds corresponding roughly to a clock speed of 187 kilohertz consequently most arithmetic instructions take 107 microseconds 93458 operations per second because they use two memory cycles the first to fetch the instruction the second to fetch or store the data word signed numbers are represented in ones complement the pdp1 has computing power roughly equivalent to a 1996 pocket organizer and a little less memory a system building block seen endon system building blocks 1103 hexinverter card pdp1 system building block 4106 circa 1963 with a us quarter note that one transistor yellow has been replaced the pdp1 uses 2700 transistors and 3000 diodes it is built mostly of dec 1000series system building blocks using microalloy and microalloy diffused transistors with a rated switching speed of 5mhz the system building blocks are packaged into several 19inch racks the racks are themselves packaged into a single large mainframe case with a hexagonal control panel containing switches and lights mounted to lie at tabletop height at one end of the mainframe above the control panel is the systems standard inputoutput solution a punched tape reader and writer the pdp1 weighed about 1600 pounds 730kg history the design of the pdp1 is based on the pioneering tx0 and tx2 computers designed and built at mit lincoln laboratory benjamin gurley was the lead engineer on the project which was by then on indefinite loan from lincoln laboratory in this setting the pdp1 quickly replaced the tx0 as the favorite machine among the budding hacker culture and served as the platform for a long list of computing innovations this list includes one of the earliest digital video games spacewar at the computer history museum tx0 alumni reunion in 1984 gordon bell said decs products developed directly from the tx2 the successor to the tx0 which had been developed at what bell thought was a bargain price at the time about us3 million at the same meeting jack dennis said ben gurleys design for the pdp1 was influenced by his work on the tx0 display the pdp1 sold in basic form for us120000 equivalent to 980000 in 2017 aecls computer was sent to science north but was later scrapped the launch of the pdp1 marked a radical shift in the philosophy of computer design it is the first commercial computer that focuses on interaction with the user rather than just the efficient use of computer cycles the first ever reference to malicious hacking is telephone hackers in mits student newspaper the tech of hackers trying up the lines with harvard configuring the pdp1 to make free calls war dialing and accumulating large phone bills peripherals pdp1 type 30 pointmode crt display and console typewriter with processor frame in background the pdp1 uses punched paper tape as its primary storage medium unlike punched card decks which could be sorted and reordered paper tape is difficult to physically edit this inspired the creation of textediting 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 letterquality printing and therefore inspired tj2 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 twocolor inked ribbon red and black and the interface allows color selection programs commonly use colorcoding 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 fiodec character coding used by the pdp1 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 pdp1 operating procedure is to output text to punched paper tape using the pdp1s high speed 60characterpersecond 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 pdp1 systems as a more convenient method of backing up programs and data and to enable early timesharing 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 graphics display the type 30 precision crt display is a pointmode device capable of addressing 1024 by 1024 addressable locations at a rate of 20000 points per second computer music mit hackers also used the pdp1 for playing music in fourpart harmony using some special hardware four flipflops directly controlled by the processor the audio signal is filtered with simple rc filters music was prepared via peter samsons harmony compiler a sophisticated textbased program with some features specifically oriented toward the efficient coding of baroque music several hours of music were prepared for it including bach fugues all of mozarts eine kleine nachtmusik the ode to joy movement concluding beethovens symphony no 9 christmas carols and numerous popular songs current status pdp1 control panel only three pdp1 computers are still known to exist and all three are in the collection of the computer history museum chm one is the prototype formerly used at mit and the other two are production pdp1c machines one of the latter serial number 55 the last pdp1 made has been restored to working order is on exhibit and is demonstrated on two saturdays every month the restoration is described on a special web page of the computer history museum the demonstrations include the game spacewar graphics demonstrations such as snowflake playing music software simulations of the pdp1 exist in simh and mess and binary image paper tapes of the software exist in the bitsaversorg archives history of computers history of computer science spacewar tech model railroad club timeline of computing notes wikimedia commons has media related to pdp1 restoring the dec pdp1 computer exhibit the computer history museums restoration project dec pdp1 collection at the computer history museum includes moving image resources on their pdp1 and the restoration project and some music files in the audio section dec pdp1 information decs 1963 programmed data processor1 handbook bitsaversorg pdp1 directory scanned documentation incl pdp1 handbook maintenance manual price list diagnostic documentation etc pdp1 music listen to mp3s of music created on the pdp1 the dot eaters entry on the pdp1 and its use in the development of the first videogame spacewar story of the development of the pdp1 from the original dec documentation including letters of delivery price sheets and photos pdp1 emulator in javascript running spacewar code dec pdp1 music video on youtube history of the pdp1 at stanford university photo of pdp1 at lrnl vtedigital equipment corporation computerspdp 18bit pdp1 pdp4 pdp7 pdp9 pdp15 12bit linc pdp5 pdp8 pdp12 linc8 decmate pdp14plc 36bit pdp6 pdp10 decsystem20 16bit pdp11 dec professional vax vax11 microvax vax 8000 vaxstation firefly vaxserver vax 6000 vax 4000 vax 9000 vaxft vax 700010000 x86 rainbow 100 vaxmate decstation multia digital personal workstation mips decstation decsystem see 36bit for decsystem20 and the pdp10decsystem10 alpha dec 3000 axp dec 4000 axp dec 700010000 axp decpc axp 150 dec 2000 axp multia alphaserver alphastation digital personal workstation authority control lccn sh2007005353 