Three men working around PDP-1
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An early brochure for the PDP-1 stated “The Programmed Data Processor (PDP) is a solid state, high speed, general purpose computer. Parallel binary arithmetic provides capability for 100,000 complete additions per second. The modular magnetic core memory has a 5 microsecond cycle time. Paper tape, typewriter and console are used for monitoring of computer operation”.

The PDP-1’s many peripherals allowed the user to interact with the machine in a variety of ways. A paper tape reader and paper tape punch was used to store and read data on paper tape; the typewriter was used to type in and print out data; a cathode ray tube (“Type 30”) display allowed programmers to view and edit programs and display graphics and games; and finally a light-pen connected to the display or monitor permitted users to point at objects or draw on the screen in way reminiscent of a mouse or touch-screen today.

Detailed Specifications:

Memory type: Magnetic coincident-core

Memory size
: 4K words (up to 16K)

Word length: 18-bit

Add time: 100,000 add/s (5 us cycle time - 200 kHz)

Instruction set: 28 single-address instructions

I/O: typewriter, paper tape, CRT, light pen, magnetic tape, precision display scope, others

Software: Diagnostics, assembler, debugger, editor, graphics, games, music, others

Number produced: approx. 50

Power: 115 VAC, 60 Hz

Size: 8’ x 2’ x 6’ (height, width, depth)

Weight: Approx. 1,200 lbs

Cost: $120,000 (1960)