Marconi Transistorised Automatic Computer control desk

The Marconi Transistorized Automatic Computer was the first all-transistor computer built by Britain's

Marconi Company The Marconi Company was a British telecommunications and engineering company that did business under that name from 1963 to 1987. Its roots were in the Wireless Telegraph & Signal Company founded by Italian inventor Guglielmo Marconi in 1897 ...

. It was designed and manufactured from around 1959. The computer employed germanium

transistors upright=1.4, gate (G), body (B), source (S) and drain (D) terminals. The gate is separated from the body by an insulating layer (pink). A transistor is a semiconductor device used to Electronic amplifier, amplify or electronic switch, switch e ...

which by this time were sufficiently reliable in room temperatures kept below about 23 degrees C. The type S3301 was a 500 kHz clocked, 20-bit word machine with two

Mullard Mullard Limited was a British manufacturer of electronic components. The Mullard Radio Valve Co. Ltd. of Southfields, London, was founded in 1920 by Captain Stanley R. Mullard, who had previously designed thermionic valves for the Admiral ...

core memory Core or cores may refer to: Science and technology * Core (anatomy), everything except the appendages * Core (manufacturing), used in casting and molding * Core (optical fiber), the signal-carrying portion of an optical fiber * Core, the centr ...

stores providing 4k of 20-bit data. The internal CPU logic was synchronised to even and odd clock signals and special signals generated via microinstruction diode boards. The memory logic had slow and fast loops to speed the transfer of sequential data bursts. A facility was provided to microstep through instructions to help with fault-finding. Processor status bits were provided, with machine instructions being decoded from 6 bits in the current address memory word. Double word data had the MSB designated a sign bit, coded as binary fractions (-1 to +1), for the square root, multiply and divide instructions. The instruction set had the usual functions based on three registers named A, B and D (C was the current address in memory register, also called M). An additional instruction assisted with checksum calculation for data transferred to and from main data stores (viz.

Sperry Rand Sperry Corporation was a major American equipment and electronics company whose existence spanned more than seven decades of the 20th century. Sperry ceased to exist in 1986 following a prolonged hostile takeover bid engineered by Burrough ...

magnetic drums). Applications included marking up radar screens with aircraft information and providing data processing for operators in a

nuclear power station A nuclear power plant (NPP) is a thermal power station in which the heat source is a nuclear reactor. As is typical of thermal power stations, heat is used to generate steam that drives a steam turbine connected to a generator that produces ele ...

. Apart from transistor failure, other common faults included power supply capacitors 'drying out' resulting in excess ripple, and poor connections on the input/output highway.

Paper tape Five- and eight-hole punched paper tape Paper tape reader on the Harwell computer with a small piece of five-hole tape connected in a circle – creating a physical program loop Punched tape or perforated paper tape is a form of data storage ...

peripherals had their own poor reliability, influenced to some degree of operator usage. Surviving computers (ex power station) are on display at the National Museum of Computing (located in

Bletchley Park Bletchley Park is an English country house and estate in Bletchley, Milton Keynes (Buckinghamshire) that became the principal centre of Allied code-breaking during the Second World War. The mansion was constructed during the years following ...

) and Jim Austin's collection near the University of York. The National Museum system is operational. Copies of original manuals and documentation are at the

Department of Computer Science, University of Manchester The Department of Computer Science at the University of Manchester is the longest established department of Computer Science in the United Kingdom and one of the largest. It is located in the Kilburn Building on the Oxford Road and currently has ...

and the Manchester

John Rylands Library The John Rylands Research Institute and Library is a late-Victorian neo-Gothic building on Deansgate in Manchester, England. It is part of the University of Manchester. The library, which opened to the public in 1900, was founded by Enriqu ...

. A performance summary specification is available online. Marconi went on to develop the

Myriad A myriad (from Ancient Greek grc, μυριάς, translit=myrias, label=none) is technically the number 10,000 (ten thousand); in that sense, the term is used in English almost exclusively for literal translations from Greek, Latin or Sinospheri ...

series of computers.

References

{{reflist Early British computers Military computers