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installation. At the far right is the IBM Model B typewriter modified by Soroban, with the Type 30 display to its left. The cabinet to the left of the display is the processor itself, the main control panel is visible just above the tabletop, the paper tape reader above it (metallic), and the output of the Teletype model BRPE paper tape punch above that (vertical slot).]] It used punched Paper Tape as its primary storage medium. Unlike Punched Card decks, which could be sorted and re-ordered, paper tape was difficult to physically edit. This inspired the creation of text-editing programs such as Expensive Typewriter and TECO . Because it was equipped with online and offline printers that were based on IBM electric Typewriter mechanisms, it was capable of what, in eighties terminology, would be called " Letter-quality Printing " and therefore inspired TJ-2, arguably the first Word Processor . The console typewriter was the product of a company named Soroban Engineering. It was an IBM Model B Electric Typewriter mechanism modified by the addition of switches to detect keypresses and Solenoid s to activate the Typebar s. It used a traditional typebar mechanism, not the "golfball" IBM Selectric Typewriter mechanism which was was not introduced until the next year. Case shifting was performed by raising and lowering the massive type basket. It was equipped with a two-color red-and-black ribbon, and the interface allowed color selection. Programs commonly used color coding to distinguish user input from machine responses. The Soroban mechanism was unreliable and prone to jamming, particularly when shifting case or changing ribbon color, and was widely disliked. Offline devices were typically Friden Flexowriter s that had been specially built to operate with the FIO-DEC character coding used by the PDP-1. Like the console typewriter, these were built around a typing mechanism that was mechanically the same as an IBM Electric Typewriter . reminiscence by Bob Mast : "The Flexowriter was first manufactured by IBM, during WWII, to be used as an automatic letter writer. After the war several IBMers bought the rights and formed Commercial Controls, Inc. They manufactured same in the old IBM Electric typewriter building in Rochester NY. In the late fifties, Friden bought Commercial Controls." However, Flexowriters were highly reliable and often used for long unattended printing sessions. Flexowriters had electromechanical paper tape punches and readers which operated synchronously with the typewriter mechanism. Typing was performed about ten characters per second. A typical PDP-1 operating procedure was to output text to punched paper tape using the PDP-1's "high speed" (60 character per second) Teletype model BRPE punch, then carry the tape to a Flexowriter for offline printing. MIT hackers also used the PDP-1 for playing music in four-part harmony, using some special hardware--four Flip-flop s directly controlled by the processor (filtered with simple RC filters). Music was prepared via Pete Samson 's ''Harmony Compiler'', a sophisticated text-based program with some features specifically oriented toward the efficient coding of Baroque Music . Several hours of music were prepared for it, including Bach Fugue s, all of Mozart's Eine Kleine Nachtmusik , Christmas carols, and numerous popular songs. It had an 18-bit data fetch. The PDP-1 was built mostly of DEC 1000-series System Module s, using Micro-Alloy and Micro-Alloy-Diffused Transistor s. Rated switching speed: 5 MHz. It is emulated by M.E.S.S. EXTERNAL LINKS
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