The original Argus was developed in 1958 as a ground-based control computer for the Bristol Bloodhound Mark 2 missile. Along with general readiness and fire-control duties, the Argus had a unique function in this system. The Bloodhound had a radar dish in the nose of the missile that had to be locked down during launch due to the vibration of the solid fuel rocket boosters that got the missile up to speed. Once the boosters were burned out and ejected, two ramjet engines took over that provided smooth thrust, allowing the radar antenna to be unlocked and start tracking the target. The Argus calculated where the target would be relative to the missile at the point of burnout, feeding that to the missile before launch and thereby allowing it to slew the radar to the correct angle when it unlocked.

During development, another team at Ferranti were positioning the system as a process control computer. Their first sale in this market was in 1962, to ICI, to operate their soda ash ammonia plant at Fleetwood, Lancashire. 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 transistors 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'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 store, while up to 64 instruction words were stored in a separate plugboard array, using ferrite pegs dropped into holes to create a "1". Op codes were 6 bits, registers 3 bits, index register (modifier) 2 bits and data address 13 bits.

The original design was followed in 1963 by the single-ALU Argus 100, which was also intended for process control use. Unlike the original, the Argus 100 used a flat 24-bit addressing scheme with both data and code stored in a single memory. Only a 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 jodrell bank MKII operation time of 72 μs. One notable use of the Argus 100 was to control the telescope in 1964. With the 100's release, the original design was retroactively renamed Argus 200 as it was considered more powerful.

This computer was donated by The Catalyst Science Discovery Centre

The following notes contain a history of this particular machine, written at the time it was collected by the Chemical Industry Museum, after being donated by ICI on the 30th January 1985.

The Argus 100 Computer from the ICI Pilkington Sullivan Works

The chemical industry museum has just taken delivery of one of the first computers ever used to control a chemical process plant. Ordered by ICI Ltd in October 1964 from Ferranti's Hollinwood factory, 6 Argus 100 computers were installed at various sites in the UK. Only one plant was designed from the beginning to be computer controlled - the paraquat plant at ICI Pilkington-Sullivan works in Widnes.

The Argus 100 from this plant, although still functional, has been replaced by several micro computers (occupying a fraction of the space previously needed) allowing the old computer room to be used more effectively. Consequently ICI generously decided to donate the computer and its input/output system to the Chemical Industry Museum.

The Argus 100 computer was the second generation of process control computer produced by Ferranti, who at the time were world leaders in this field, and the original Argus was re-designated '200 series' when the newer model was introduced.

Today both these computers would be considered rather quaint. The 200 series was housed in a 6 foot high grey painted steel cabinet, and it was programmed by inserting Ferrite Pegs into holes in a printed circuit board. Core storage was achieved using a Ferrite bead matrix and the logic circuits were put together using discrete components assembled onto removable printed circuit cards. This added up to a reliable, if somewhat temperature sensitive machine, which promised much in the process control field.

The first industrial application of the 200 series was to control the solvay process at ICI's Fleetwood works in 1961, but the impetus for its development came surprisingly from military R & D where it was used to control the Bloodhound surface to air missile developed by BAC. In any case the success of the Fleetwood installation, although not without its problems, led to the 1964 orders mentioned above and hence the paraquat installation using the Argus 100. This was a revised, scaled down and less expensive development, aimed specifically at process control applications. The program could now be loaded on a punch paper tape, a vast improvement over the ferrite pegs of the 200 series. Otherwise the physical construction was similar although the cabinet was now only 4 foot high.

In 1965 when the paraquat plant came on stream, there were several advantages gained by the introduction of direct computer control, compared with the analogue controllers used previously on the No.1 (Pilot) plant.

Firstly there was the benefit if instantaneous control over the process which was not previously possible. This enabled much finer adjustment and hence an increase in efficiency when a small increase (say 1%) would mean a reasonable reduction in costs because expensive raw materials were used. Secondly, improved alarming was possible. Here two types of alarm signal could be generated. If any variable deviated by (say) +/-10% from a normal value then an alarm was given. Alternatively, there was an absolute alarm which occurred if a certain value, either high or low was reached.

Perhaps the most important advantage was the facility for recording the operating conditions of the plant. Every five minutes, the computer would dump this information via a printer. Now for the first time, a complete analysis of the process was available to study, leading again to greater efficiency, as the computer was reprogrammed, taking into account the knowledge gained. This also provided valuable historical evidence, if any serious malfunction occurred.

Although this was a donation we must sincerely thank many of our donors for providing the funding to allow us to hire a suitable van and man power for us to collect this important computer.

A very fascinating and interesting article entitled Bloodhound on my Trail has been forwarded to us by Jonathan Aylen from Manchester Institute of Innovation Research, University of Manchester, UK who is the author of this article published int. j. for the history of eng. & tech., Vol. 82 No. 1, January, 2012, 1–36  and is available to view HERE regarding this machine Ferranti Argus 100 from ICI Paraquat Plant at Widnes. Our very grateful thanks to Jonathan Aylen.

A further fascinating article concerning the Bloodhound as well as the Harrier jump jet by Jonathan Aylen and Mike Pryce is available to view HERE mentioning Scilla Bretscher who was given enormous responsibility for programming the Argus 100 at the No.2 Paraquat plant.

Manufacturer: Ferranti
Date: 1963

This exhibit has a reference ID of CH32443. Please quote this reference ID in any communication with the Centre for Computing History.