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Ferranti Ferranti or Ferranti International plc was a UK electrical engineering and equipment firm that operated for over a century from 1885 until it went bankrupt in 1993. The company was once a constituent of the FTSE 100 Index. The firm was known ...
's Argus computers were a line of industrial control computers offered from the 1960s into the 1980s. Originally designed for a military role, a re-packaged Argus was the first digital computer to be used to directly control an entire factory. They were widely used in a variety of roles in Europe, particularly in the UK, where a small number continue to serve as monitoring and control systems for
nuclear reactor A nuclear reactor is a device used to initiate and control a fission nuclear chain reaction or nuclear fusion reactions. Nuclear reactors are used at nuclear power plants for electricity generation and in nuclear marine propulsion. Heat from nu ...
s.


Original series


Blue Envoy, hearing aid computer

The original concept for the computer was developed as part of the Blue Envoy missile project. This was a very long-range
surface-to-air missile A surface-to-air missile (SAM), also known as a ground-to-air missile (GTAM) or surface-to-air guided weapon (SAGW), is a missile designed to be launched from the ground to destroy aircraft or other missiles. It is one type of anti-aircraft syst ...
system with a range on the order of . To reach these ranges, the missile was "lofted" in a nearly vertical trajectory at launch, so that it spent more time flying through the thin high-altitude air. Once it reached high altitude, it would tip over and begin to track the target. During the initial vertical climb the missile's radar would not be able to see the target, so during this period it was command guided from the ground. Argus began as a system to read the radar data, compute the required trajectory, and send that to the missile in-flight. The system not only had to develop the trajectory, but also directly controlled the control surfaces of the missile and thus had a complete control feedback system. Development was carried out by Maurice Gribble at Ferranti's Automation Division in
Wythenshawe Wythenshawe () is a district of the city of Manchester, England. Historically in Cheshire, Wythenshawe was transferred in 1931 to the City of Manchester, which had begun building a massive housing estate there in the 1920s. With an area of approx ...
starting in 1956. The system used the new OC71 transistors from Mullard, originally designed for use in
hearing aid A hearing aid is a device designed to improve hearing by making sound audible to a person with hearing loss. Hearing aids are classified as medical devices in most countries, and regulated by the respective regulations. Small audio amplifiers su ...
s. They could only be run at the low speed of 25 kHz, but this was enough for the task. Blue Envoy was cancelled in 1957 as part of the sweeping 1957 Defence White Paper. Ferranti decided to continue the development of the computer for other uses. During a visit by
Prince Philip, Duke of Edinburgh Prince Philip, Duke of Edinburgh (born Prince Philip of Greece and Denmark, later Philip Mountbatten; 10 June 1921 – 9 April 2021) was the husband of Queen Elizabeth II. As such, he served as the consort of the British monarch from El ...
in November 1957, they set up a system with an automotive headlamp connected to a handle that could be moved by hand to shine at any point on a wall, while the computer attempted to move a second headlamp to lay on the same spot on the wall.


Prototype Argus

Ferranti continued development of the system, and during 1958 they completed a prototype of a commercial product which they showed publicly for the first time at the Olympia in November. This machine used new circuitry that ran at the much faster rate of 500 kHz. The name "Argus" (from the Greek God of that name) was assigned the next year, keeping with the Ferranti tradition of using Greek names for their computers. They selected Argus as this was the all-seeing god, appropriate for a machine that would be tasked with controlling complex systems. The new system had a number of differences from the hearing aid machine. Among these was the introduction of
interrupt In digital computers, an interrupt (sometimes referred to as a trap) is a request for the processor to ''interrupt'' currently executing code (when permitted), so that the event can be processed in a timely manner. If the request is accepted ...
s to better handle timing of various events. The earlier machine was so slow that these sorts of issues were dealt with simply by checking every physical input in a loop, but with the much faster performance of the new design this was no longer appropriate as most of the tests would reveal no changes and thus be wasted. These sorts of tasks were now controlled by interrupts, so the device could indicate when its data was ready to be processed. The system added
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 ...
for temporary storage, replacing the flip-flops from the earlier system, and a plugboard for programming. The first delivery would be to
Imperial Chemical Industries Imperial Chemical Industries (ICI) was a British chemical company. It was, for much of its history, the largest manufacturer in Britain. It was formed by the merger of four leading British chemical companies in 1926. Its headquarters were at M ...
(ICI) to go into use as the control system for ICI's
soda ash Sodium carbonate, , (also known as washing soda, soda ash and soda crystals) is the inorganic compound with the formula Na2CO3 and its various hydrates. All forms are white, odourless, water-soluble salts that yield moderately alkaline solutions ...
/
ammonia Ammonia is an inorganic compound of nitrogen and hydrogen with the formula . A stable binary hydride, and the simplest pnictogen hydride, ammonia is a colourless gas with a distinct pungent smell. Biologically, it is a common nitrogeno ...
plant at
Fleetwood Fleetwood is a coastal town in the Borough of Wyre in Lancashire, England, at the northwest corner of the Fylde. It had a population of 25,939 at the 2011 census. Fleetwood acquired its modern character in the 1830s, when the principal lando ...
. An agreement was reached in March 1960 and the machine was installed April/May 1962. This was the first large factory to be controlled directly by a digital computer. Other European sales followed. The Argus circuitry was based on
germanium Germanium is a chemical element with the symbol Ge and atomic number 32. It is lustrous, hard-brittle, grayish-white and similar in appearance to silicon. It is a metalloid in the carbon group that is chemically similar to its group neighbo ...
transistor 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 ...
s with 0 and -6 volts representing binary 1 and 0, respectively. The computer was based on a 12-bit word length with 24-bit instructions. The arithmetic was handled in two parallel 6-bit
ALU ALU, Alu or alu may refer to: Computing and science ;Computing *Arithmetic logic unit, a digital electronic circuit ;Biology * Alu sequence, a type of short stretch of DNA *'' Arthrobacter luteus'', a bacterium Organizations * Abraham Lincoln ...
s operating at 500 kHz. Additions in the ALU took 12 µs, but adding in the memory access time meant simple instructions took about 20 µs. Double-length (24-bit) arithmetic operations were also provided. Data memory was supplied in a 12-bit, 4096 word,
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 ...
store, while up to 64 instruction words were stored in a separate plugboard array, using ferrite pegs dropped into holes to create a "1". Opcodes were 6 bits, registers 3 bits, index register (modifier) 2 bits and data address 13 bits.


Bloodhound Mark II

Shortly after the cancellation of the Blue Envoy in 1957, an emergency meeting between the primary contractors, Ferranti and Bristol Aerospace, led to the idea of combining components of the Blue Envoy with the existing Bristol Bloodhound to produce a much more capable design. This produced the Bloodhound Mark II, roughly doubling the range to about and using the new radar systems from the Envoy which allowed the missile to track targets much closer to the ground whilst also much more resistant to radar jamming. Unlike Blue Envoy, Bloodhound was expected to be able to see the target through the entire attack. Guidance was semi-active radar homing, with an illuminator radar lighting up the targets, and a receiver in the missile using the reflected signal to track. For this to work, the illuminator had to be pointed at the target using information from a separate tactical control radar, and the receiver in the nose of the missile had to be pointed at the target. The illuminator and missiles would not necessarily be close together, complicating the calculations. Further, the receiver had to filter out signals that were not of the expected
Doppler shift The Doppler effect or Doppler shift (or simply Doppler, when in context) is the change in frequency of a wave in relation to an observer who is moving relative to the wave source. It is named after the Austrian physicist Christian Doppler, who ...
ed frequency range, so the computer also had to calculate the expected frequency shift to set the receiver's filters. The accuracy required of the calculations was beyond the capability of small military computers used to that point. An experimental system by Derek Whitehead using a digital computer was easily able to accomplish the calculations. He suggested placing the computers at the Orange Yeoman radar sites as calculation centers that would feed this information to the missile batteries. Whitehead was a friend of Gribble's and was aware of his work on a small computer, and first raised the issue sometime in autumn 1959. Once the decision had been made to move to a digital computer, all sorts of secondary tasks were handed off to the machine. This included everything from maintenance testing to missile launch control to the calculation of Doppler "zero points" where the signal would be expected to drop to zero as the target crossed at right angles to the radar.


Argus 200 and 100

The original design was followed in 1963 by the single-ALU Argus 100, which cost around £20,000 (equivalent to approximately £430,000 ). Unlike the original, the Argus 100 used a flat 24-bit addressing scheme with both data and code stored in a single memory. A smaller 5-bit opcode was used in order to simplify the basic logic and gain an address bit. The single ALU and other changes resulted in a basic operation time of 72 μs. One notable use of the Argus 100 was to control the Jodrell Bank Mark II telescope in 1964. With the 100's release, the original design was retroactively renamed Argus 200. The Argus 200 model would eventually sell 63 machines, and the 100 14.


Argus 300

The design of the Argus 300 was started in 1963, with the first delivery in 1965. This was a much faster machine featuring a fully parallel-architecture
arithmetic logic unit In computing, an arithmetic logic unit (ALU) is a combinational digital circuit that performs arithmetic and bitwise operations on integer binary numbers. This is in contrast to a floating-point unit (FPU), which operates on floating point numb ...
, as opposed to the earlier and much slower serial units. Its instruction set was nevertheless fully compatible with the Argus 100. The 300 was very successful and used throughout the 1960s in various industrial roles. A variant of the 300 was the Argus 350, which allowed external access to its core to allow
direct memory access Direct memory access (DMA) is a feature of computer systems and allows certain hardware subsystems to access main system memory independently of the central processing unit (CPU). Without DMA, when the CPU is using programmed input/output, it is ...
. This improved performance of
input/output In computing, input/output (I/O, or informally io or IO) is the communication between an information processing system, such as a computer, and the outside world, possibly a human or another information processing system. Inputs are the signals ...
, avoiding having to move data via code running on the processor. The 350 was used in various military simulators, including the
Royal Navy The Royal Navy (RN) is the United Kingdom's naval warfare force. Although warships were used by Kingdom of England, English and Kingdom of Scotland, Scottish kings from the early medieval period, the first major maritime engagements were foug ...
for frigate, submarine and helicopter-based anti-submarine training, and the
Royal Air Force The Royal Air Force (RAF) is the United Kingdom's air and space force. It was formed towards the end of the First World War on 1 April 1918, becoming the first independent air force in the world, by regrouping the Royal Flying Corps (RFC) an ...
for a Bloodhound Mk.II simulator and the
Vickers VC10 The Vickers VC10 is a mid-sized, narrow-body long-range British jet airliner designed and built by Vickers-Armstrongs (Aircraft) Ltd and first flown at Brooklands, Surrey, in 1962. The airliner was designed to operate on long-distance rou ...
flight simulator built at
Redifon Rediffusion was a business that distributed radio and TV signals through wired relay networks. The business gave rise to a number of other companies, including Associated-Rediffusion, later known as Rediffusion London, the first ITV ( commerc ...
and delivered to RAF Brize Norton in 1967. The model used on the VC10 Simulator was a 3520B, this meant that it had (20)kWords of memory and a (B)acking Store. Redifon also used the 350 on the Air Canada DC9 flight simulator that was installed in Montreal in the Spring of 1966. The 350's were delivered in the 1967 to 1969 timeframe.


Silicon replacements

The design of the Argus 400 started at the same time as the Argus 300. In logical terms the 400 was similar to the earlier 100, using serial ALUs. However, it featured an entirely new electrical system. Previous machines used germanium transistors to form the logic gates. The Argus 400 used silicon transistors in a NOR-logic designed by Ferranti
Wythenshawe Wythenshawe () is a district of the city of Manchester, England. Historically in Cheshire, Wythenshawe was transferred in 1931 to the City of Manchester, which had begun building a massive housing estate there in the 1920s. With an area of approx ...
called ''MicroNOR II'', with more "conventional" logic where 0 and +4.5 represented binary 1 and 0, respectively. The rest of the world however used 0 volts to represent 0 and + 2.4 (to 5) volts to represent 1. This was called NAND logic. They are in fact both the same circuitry. When Texas Instruments brought out their “74” series of integrated circuits the specification of MicroNOR II was changed from 4.5 volts to 5 volts so the two families could work together. The machine was packaged to fit into a standard
Air Transport Rack The atmosphere of Earth is the layer of gases, known collectively as air, retained by Earth's gravity that surrounds the planet and forms its planetary atmosphere. The atmosphere of Earth protects life on Earth by creating pressure allowing for ...
. Multilayer
PCBs Polychlorinated biphenyls (PCBs) are highly carcinogenic chemical compounds, formerly used in industrial and consumer products, whose production was banned in the United States by the Toxic Substances Control Act in 1979 and internationally by ...
were not routine in 1963 and Ferranti developed processes for bonding the boards and plating through the circuit boards. The drawing office had to learn how to design multilayer boards, which was first laid out on tape then transferred to film. It took around two years for the Argus 400 to go into production, with the first delivery in 1966, weighing more than . The Argus 500, designed about 3 years later, used parallel arithmetic and was much faster. It was designed to be plugged into a larger 19 inch rack mounted frame, together with up to four core store (memory) units. The Argus 400 was repackaged to be the same as the Argus 500 and the two machines were plug compatible. The Argus 400 used 18 small PCBs for its CPU each of which was wire-wrapped to the backplane using 70 miniature wire wraps. Removing a card was tedious. The Argus 500 initially used the same packages, and also wire-wrap, on larger boards, but later versions employed dual-in-line ICs which were soldered flat onto the PCB and were much easier to remove. Like the earlier designs, the 400 and 500 used the same 14-bit address space and 24-bit instruction set and were compatible. The 500 added new instructions that used three-bits of the accumulator for offset indexing as well. Both machines ran at a 4 MHz basic clock cycle, much faster than the earlier machines' 500 kHz. Both used core memory which was available in two cycle times. The Argus 400 used a 2 μs core whereas the Argus 500 had 2 μs in earlier machines and 1 μs for later ones, doubling performance. The difference between the 400 and 500 was similar to the split between the 100 and 300, in that the 500 had a parallel ALU and the 400 was serial. The Argus 400 had an add time (two 24 bit numbers) of 12 μs. The Argus 500 (with 1 μs store) took 3 μs. Divide (the longest instruction) took 156 μs on the Argus 400 and the Argus 500 took 9 μs. The Argus 500 was of course much more expensive. A CORAL 66 high-level programming language compiler for the Argus 500 was developed by the Royal Signals and Radar Establishment under contract to Ferranti for use in industrial control and automation projects. Typical Argus 500 installations were chemical plants (process control) and nuclear power stations (process monitoring). A later application was for Police Command and Control installations, one of the more famous ones being for Strathclyde Police in Glasgow. This system provided the first visual display of resource locations using maps provided by 35mm slide projectors projecting through a port-hole in the tube of the VDU screen. An Argus 400 replaced the 100 at Jodrell Bank in 1971. There was a special version of the Argus 400 made for the Boadicea seat booking network for
BOAC British Overseas Airways Corporation (BOAC) was the United Kingdom, British state-owned airline created in 1939 by the merger of Imperial Airways and British Airways Ltd. It continued operating overseas services throughout World War II. ...
. This removed the multiply and divide functions as these used a significant number of expensive JK flip-flops and it was cost effective at the time to save these 24 and a few other components. Overall, the 500 proved to be one of Ferranti's best-selling products, and found especially wide use on oil platforms during the opening of the
North Sea The North Sea lies between Great Britain, Norway, Denmark, Germany, the Netherlands and Belgium. An epeiric sea on the European continental shelf, it connects to the Atlantic Ocean through the English Channel in the south and the Norwegian S ...
oil fields during the 1970s.


Argus 600 and 700

Breaking with the past, the next series of Argus machines were completely new designs and not backward compatible. The Argus 600 was an 8-bit machine, intended for use by manufacturers of electrical and electronic equipment who required a relatively simple computer or programmable control device. It possessed a basic
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 ...
of 1,024
words A word is a basic element of language that carries an objective or practical meaning, can be used on its own, and is uninterruptible. Despite the fact that language speakers often have an intuitive grasp of what a word is, there is no conse ...
, expandable in blocks of the same size up to a maximum of 8,192 words. A simple
mnemonic A mnemonic ( ) device, or memory device, is any learning technique that aids information retention or retrieval (remembering) in the human memory for better understanding. Mnemonics make use of elaborative encoding, retrieval cues, and image ...
programming language called ASSIST, comprising 17 single-address instructions, was developed for the new machine. Costing around £1,700 when introduced in 1970, at the time the Argus 600 was cheapest digital computer available in the United Kingdom. It could be linked directly or via telephone lines to larger computers and its hardware interface allowed modules from the Argus range of peripheral and plant connection equipment to be added as required. The Argus 600 was followed by the Argus 700, which used 16-bit architecture. Design of the 700 started around 1968/9 and the range was still in production in the mid 1980s achieving international success for industrial and military applications. The 700 is still operational at several British nuclear power stations in 2020 in control and data processing applications. It was also used as a production control platform for companies such as
Kodak The Eastman Kodak Company (referred to simply as Kodak ) is an American public company that produces various products related to its historic basis in analogue photography. The company is headquartered in Rochester, New York, and is incorpor ...
. The Argus 700 could be configured in shared memory multi-processor configurations. The Argus 700E was a low-end model. The Argus 700F used 500 ns cycle time MOS memory of up to 64k 16-bit words. The Argus 700G supported a
virtual address space In computing, a virtual address space (VAS) or address space is the set of ranges of virtual addresses that an operating system makes available to a process. The range of virtual addresses usually starts at a low address and can extend to the hig ...
with up to 256k words of memory. The Argus 700S had the option of faster 150 ns bipolar memory with independent access for input-output processors. The Argus 700 also played an important historical role in the development of
packet switching In telecommunications, packet switching is a method of grouping Data (computing), data into ''network packet, packets'' that are transmitted over a digital Telecommunications network, network. Packets are made of a header (computing), header and ...
networks in the UK. These machines were used by Ferranti during early experiments at the
General Post Office The General Post Office (GPO) was the state mail, postal system and telecommunications carrier of the United Kingdom until 1969. Before the Acts of Union 1707, it was the postal system of the Kingdom of England, established by Charles II of En ...
as the basis for early routers. In this respect they are similar to the
Interface Message Processor The Interface Message Processor (IMP) was the packet switching In telecommunications, packet switching is a method of grouping Data (computing), data into ''network packet, packets'' that are transmitted over a digital Telecommunications netwo ...
s built in the US to serve a similar role during the development of the
Internet The Internet (or internet) is the global system of interconnected computer networks that uses the Internet protocol suite (TCP/IP) to communicate between networks and devices. It is a ''internetworking, network of networks'' that consists ...
. Over 70 Argus 700G processors were used in the control and instrumentation systems of the
Torness Torness nuclear power station is a nuclear power station located approximately east of Edinburgh at Torness Point near Dunbar in East Lothian, Scotland. It was the last of the United Kingdom's second generation nuclear power plants to be commi ...
nuclear power station, which had a far more sophisticated control system than earlier members of the advanced gas-cooled reactor fleet, including Digital Direct Control (DDC) of the reactors. When first installed it was probably the most sophisticated and complex computerised control system for a nuclear power station worldwide; the system was implemented using the CORAL high-level programming language. Each reactor in the dual reactor station had 10 input multiplexing computers, 11 control dual-processor computers, and a supervisory triple-processor computer with a standby backup.


M700

The M700 series of computers was based on the architecture and instruction set of the Ferranti Argus 700 computer series. Both M700 computers and Argus 700 computers have a common overall instruction set. However, particular models do not necessarily implement the complete instruction set. M700 included a range of computers which were all based on the same architectural features and instruction set ensuring a high level of compatibility and interchangeability in hardware and software terms. Within these limits there existed different implementations from more than one manufacturer to reflect specific commercial and application requirements.


Notes


References


Citations


Bibliography

*


External links

* Argus 100-500, Micronor I and II: {{Cite web, url=http://www.ourcomputerheritage.org/minicomp.htm, title=FCL History & Minicomputers, date=March 2016, website=Computer Conservation Society, others=Ferranti Ltd. and minicomputers - technical information, access-date=2018-04-26 Early British computers
Argus Argus is the Latinized form of the Ancient Greek word ''Argos''. It may refer to: Greek mythology * See Argus (Greek myth) for mythological characters named Argus **Argus (king of Argos), son of Zeus (or Phoroneus) and Niobe **Argus (son of Ar ...
Military computers Avionics computers Industrial computing Computer-related introductions in 1958 Computer-related introductions in 1962