The path not taken.
- Oct 9, 2009
- Reaction score
The Ferranti F100-L was the first European designed and manufactured 16-bit microprocessor.
Launched in 1976, the F100-L was designed by Ferranti Computer Systems Ltd in their Bracknell, UK design centre. The chips were then fabricated in Ferranti Electronics Ltd’s Gem Mill works in Manchester.
The F100-L project started in the early 1970s with the intention of creating complete microprocessor based solutions for military applications as well as serving the needs of various Ferranti divisons. The military requirement included the ability to operate over a wide temperature range of -55C to +125C and to be resistant to the effects of radiation. The 16 bit word size was chosen as the system was seen to be a way of downsizing existing applications running using mini-computers and software.
As well as being one of the first of the 16 bit processors the F100-L was unusual in that it was designed using a bipolar technology when other manufacturers had already turned to planar MOS processes to improve component densities. The choice of bipolar technology was driven by the radiation hardness requirement and eventually it was shown that the F100-L was almost totally latch-up resistant even after significant doses of radiation. Ferranti were already technology leaders in the fabrication and application of bipolar design for both linear and logical applications through their Common Diffusion Isolation (CDI) process.
Although little information is publicly available on Ferranti turn-key systems for military applications, three stand out as having generated sufficient demand to keep the processor and support chips in production from the original 1976 launch right up into the mid 1990s.
The F100-L was the also subject of a number of application studies and trials although it’s not clear how many of these resulted in sales of more than sample quantities.
- The BAe Sea Eagle Missile System 
Sea Eagle was an air-launched anti-ship missile originally introduced in 1981 and used in the UK Armed Forces until the late 1990s, and still in use in the Indian Navy as alte as 2009. 
The F100-L provides the on-board digital flight computer controlling the flight path of the missile until the target is acquired by the radar homing head during the final sea skimming phase of an attack. An upgrade program was abandoned on cost grounds in the mid 1990s so it’s possible that the F100-L saw out the entire Sea Eagle lifespan.
- The Ferranti Falcon Integrated Fire Control System (IFCS) for tanks and AFVs
“The Ferranti Falcon Fire Control System is a digital system based on the F100-L Microprocessor providing a versatile and cost-effective means of enhancing the combat capability of gun-aimed fighting vehicles. Compact Dimensions, simplicity of operation and low cost enusre the Falcon application is not restricted to main battle tanks.”
– Janes Weapon Systems, 1985/86 
The Ferranti Falcon system may originally have been developed for the MBT-80 tank, intended as a British Chieftain replacement, but the MBT-80 project itself was abandoned in 1980[32a]. Whatever its origins, the Ferranti Falcon system itself continued into production and was offered as an option for Chieftain 900 tanks [32b], and was used on the Brazilian MB-3 Tamoyo tanks .
A gun control predictor for smaller calibre Naval cannon, possibly related to the Ferranti Falcon, was also offered and adopted at least by the Brazilian navy.
- The Naval CACS-1, Computer Assisted Command System, and later CAAIS 450, Computer Aided Action Information System.
Both of these systems used Ferranti F100-L powered terminals to support multi-processor Ferranti FM1600 and Argus M700 computer systems.
“CAAIS 450 is a distributed processing system using the FM1600E computer and Coral 66 software language. It operates at 650 kips and has a memory of 1.2 million words. It is designed to fit a wide range of warships down to fast attack craft size and to interface with a fire-control system. The system also uses new consoles each with its own computer, core, Dragon display drive (using Ferranti F100L microprocessors) and input/output devices. There are two types of display system; two-operator and single-operator, and a typical configuration would be three two-man consoles. These may be supplemented by one two-man or two one-man consoles, the latter being either joined or autonomous.”
– Janes Naval Systems, No. 25, 
The CACS-1 system was widely adopted in Royal Navy vessels, including in Type 22 frigates. The CAAIS was also used by the Navy in Hunt Class minesweepers, but also offered for export and used in Brazilian Navy Inhaúma class ships. 
The highest profile application was the F100-L’s inclusion in the University of Surrey’s UoSAT program, where the F100-L was the heart of the secondary computer unit launched into space. [9,11]
Other applications and research projects include
- Engine management control
- Ultra Electronic Controls Ltd. announced an engine management system in 1979, and later published technical papers [22,23]
- Dowty Group displayed an F100-L digital speed and temperature limiter at the Farnborough Airshow in 1978 
- Proceedings of the ASME include another research paper on Helicopter Engine Management control 
- A standard spacecraft compute module was offered by the British Aerospace Space and Communications Division 
- several papers have been published on control of nuclear test equipment using the CAMAC protocol
- medical instrumentation and monitoring 
- application of micro processors in Air Traffic Control 
- an RAE study into airframe stress monitoring using F100-L micro processor for data acquisition and management in flight prior to download for later analysis