Sunday, 10 January 2010
DEC PDP-1 - Applications (TOSEC-v2009-10-23), DEC PDP-1 - Demos (TOSEC-v2009-10-23) and DEC PDP-1 - Games (TOSEC-v2009-10-23)
It has an 18-bit word and had 4 kilowords as standard main memory (equivalent to 9 kilobytes, or 9,000 bytes), upgradable to 64 kilowords (144 KB). The magnetic core memory's cycle time was 5 microseconds (corresponding very roughly to a "clock speed" of 200 kilohertz; consequently most arithmetic instructions took 10 microseconds (100,000 operations per second) because they had two memory cycles: one for the instruction, one for the operand data fetch. Signed numbers were represented in one's complement.
The PDP-1 was built mostly of DEC 1000-series System Building Blocks, using Micro-Alloy and Micro-Alloy-Diffused transistors with a rated switching speed of 5 MHz.
The PDP-1 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 solenoids to activate the typebars. It used a traditional typebar mechanism, not the "golfball" IBM Selectric typewriter mechanism, which 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 Flexowriters 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. 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." (Wikipedia)
DEC PDP-1 - Applications (TOSEC-v2009-10-23)
DEC PDP-1 - Demos (TOSEC-v2009-10-23)
DEC PDP-1 - Games (TOSEC-v2009-10-23)