Vacuum-tube computers, now called first-generation computers, are programmable digital computers using vacuum-tube logic circuitry. They were preceded by systems using electromechanical relays and followed by systems built from discrete transistors. Often vacuum-tube computers made extensive use of solid-state ("crystal") diodes to perform AND and OR logic functions per diode-resistor logic (DRL) also diode–transistor logic (DTL), and only used vacuum tubes to amplify signals between stages or to construct elements such as flip-flops, counters, and registers. The solid-state diodes reduced the size and power consumption of the overall machine. Some later computers on the list had both vacuum tubes and transistors.
This list of vacuum-tube computers is sorted by date put into service, and notes the vacuum tube:Crystal diode semiconductor (VT:CD) ratio, e.g., "747 V : 10,500 D" for SEAC (computer): Computer Date Units VT:CD Notes Arthur Halsey Dickinson (IBM) 19391 Not programmable, executed addition and subtraction, the first electronic output (display)Dickinson A.H., "Accounting Apparatus", US Pat. 2,580,740, filed Jan. 20, 1940, granted Jan. 1, 1952 Joseph Desch, NCR3566 (NCR) 19391 Not programmable, executed addition and subtraction, thyratron decadesDesch J.R., "Calculating Machine", US Pat. 2,595,045, filed March 20, 1940, granted Apr. 29, 1952 Atanasoff–Berry Computer 19421 Not programmable, but could solve a system of linear equations. Colossus 194310 The Mark II version was the first programmable (by switches and plug panels) special-purpose (cryptanalysis) electronic digital computer. It was used in breaking the German Lorenz cipher; and superseded the Heath Robinson (codebreaking machine). A working replica is demonstrated at The National Museum of Computing, Bletchley Park. ENIAC 19451 18k : 0 First large-scale general-purpose programmable electronic digital computer. Built by the University of Pennsylvania's Moore School of Electrical Engineering for the U.S. Army's Ballistic Research Laboratory. Originally programmed by wiring together components, by April 1948, it had been converted to a form of stored-program operation. It was decimal in nature, not binary. 19481 550 : 0 First electronic stored-program computer, worked June 1948; prototype for the Mark 1. Working replica demonstrated daily in Manchester Museum of Science and Industry. Manchester Mark 1 19491 4.1k : 0 Provided a computing service from April 1949. First index registers. Re-engineered 1951 as Ferranti Mark 1. EDSAC 19491 3k : 0 First ran on 6 May 1949, and provided a computing service for Cambridge University until 1958. Working replica being built at The National Museum of Computing, Bletchley Park. BINAC 19491 700 : 0 First stored-program computer to be sold, but it did not work for the customer. CSIRAC 19491 2k : 0 Oldest surviving complete first-generation electronic computer — unrestored and non-functional. SEAC 195011 : 14 First U.S. stored-program computer to become operational. Built by and for the U.S. National Bureau of Standards. Used solid-state diode circuits for its logic. Several computers were based on the SEAC design. SWAC 195012.3k : 0 Built for the U.S.'s National Bureau of Standards, it had 2,300 vacuum tubes. It had 256 words (each of 37 bits) of memory, using Williams tubes ERA Atlas 1950 2.7k : 0 Military version of Univac 1101; it used 2,700 vacuum tubes for its logic circuits. MADDIDA 195061 : 17Special-purpose digital computer for solving a system of differential equations. Forty-four integrators were implemented using a magnetic drum with six storage tracks. The interconnections of the integrators were specified by writing an appropriate pattern of bits onto one of the tracks. Pilot ACE 19501 800 : 0 Based on a full-scale design by Alan Turing Elliott 152 195011k : 0 Naval fire control computer, real-time control system, fixed program Elliott 153 195011k : 0 GCHQ radio signal directional finding computer, based on the Elliott 152, with programs stored on a magnetic disk Harvard Mark III 195111 : 0.3 It used 5,000 vacuum tubes, 1,500 crystal diodes and also ~2,000 relays. Ferranti Mark 1 195194.1k : 0 First commercially available computer, based on Manchester Mark 1. EDVAC 195111 : 2 The successor to ENIAC, and also built by the University of Pennsylvania's Moore School of Electrical Engineering for the U.S. Army's Ballistic Research Laboratory. One of the first stored-program computers to be designed, but its entry into service was delayed. EDVAC's design influenced a number of other computers. Harwell Dekatron Computer (The "WITCH") 19511959 : 0 Now officially the oldest original working computer in the world. It is frequently demonstrated at The National Museum of Computing, Bletchley Park. Whirlwind 195111 : 1.9 Parallel logic, approx 5,000 vacuum tubes. This was the machine for which magnetic-core memory was developed; as soon as it was proven on the MTC, it replaced the unreliable MIT electrostatic memory. It was a bit-slice implementation with rows of relay racks (one bit per rack) packaged in a building. UNIVAC I 1951461 : 3.2 Mass-produced; 46 were made. LEO I 195117k : 0 First computer for commercial applications. Built by the J. Lyons and Co. restaurant and bakery chain, based on the EDSAC design.MESM195116k : 0First universally programmable computer in USSR, built near Kiev, used 6,000 vacuum tubes. Designed basically near to Von Neumann architecture but had two separate banks of memory - one for programs and another for data (Harvard architecture).IAS machine195112.3k : 0Built at the Institute for Advanced Study (IAS), it was the basis of about 15 other computers. Sometimes called the von Neumann machine, since the design was described by John von Neumann (the Von Neumann architecture). It used 2,300 tubes (CPU + Memory + Power + I/O) of which 1,700 were CPU logic. UNIVAC 1101 19511 : 0.9 Designed by ERA and publicly announced 1951 (Dec). The name "1101" is binary for 13, a reference to project "Task 13". It used 2,700 vacuum tubes and 2,385 crystal diodes. HEC 1