The PDP-1 (Programmed Data Processor-1) is the first computer in Digital Equipment Corporation's PDP series and was first produced in 1959. It is famous for being the computer most important in the creation of hacker culture at Massachusetts Institute of Technology, BBN and elsewhere. The PDP-1 is the original hardware for playing history's first game on a minicomputer, Steve Russell's Spacewar! Description The PDP-1 uses an 18-bit word size and has 4096 words as standard main memory (equivalent to 9,216 eight-bit bytes, though the system actually divides an 18-bit word into six-bit characters), upgradable to 65,536 words. The magnetic-core memory's cycle time is 5.35 microseconds (corresponding roughly to a clock speed of 187 kilohertz); consequently most arithmetic instructions take 10.7 microseconds (93,458 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 PDP-1 has computing power roughly equivalent to a 1996 pocket organizer and a little less memory. The PDP-1 uses 2,700 transistors and 3,000 diodes. It is built mostly of DEC 1000-series System Building Blocks, using micro-alloy and micro-alloy diffused transistors with a rated switching speed of 5MHz. The System Building Blocks are packaged into several 19-inch 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 table-top height at one end of the mainframe. Above the control panel is the system's standard input/output solution, a punched tape reader and writer. The PDP-1 weighed about . History The design of the PDP-1 is based on the pioneering TX-0 and TX-2 computers, designed and built at MIT Lincoln Laboratory. Benjamin Gurley was the lead engineer on the project. After showing a prototype at the Eastern Joint Computer Conference in December 1959, DEC delivered the first PDP-1 to Bolt, Beranek and Newman (BBN) in November 1960, and it was formally accepted in early 1961. In September 1961, DEC donated the PDP-1 to MIT, where it was placed in the room next to its ancestor, the TX-0 computer, which was by then on indefinite loan from Lincoln Laboratory. In this setting, the PDP-1 quickly replaced the TX-0 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