Marconi Myriad

The Marconi Myriad was an early computer designed by the Marconi Company in the 1960s and assembled in the same factory as the English Electric System 4/30.

Myriad was a 24-bit machine largely built using integrated circuits from Ferranti. These were packaged in small "TO8" type cans. The architecture was "conventional", and was developed largely by the in-house Marconi team that designed similar, but physically larger computers based on SB345 discrete surface-barrier transistors. These machines were used successfully by the Royal Radar Establishment (RRE) in the UK, and by the Swedish Government in their "Fur Hat" defense system. They also provided flight data for UK military air traffic control for 15 years. In Australia, Myriads were used as part of the AF/TPS-802 "HUBCAP" air-defence system from 1967-97.

The Myriad 1 computer was mounted in a small desk format, and was far smaller than any comparable machine at the time. 8-bit paper tape was (somewhat) standard input (the software could handle data input in either the ASCII or the rather idiosyncratic KDF9 character codes) - but a high speed 1000-characters/second (electrostatic) reader (made by Facit) was capable of projecting paper tape across a room in spectacular fashion. A high-speed printer was provided. The major machine cycle time was around 800 nanoseconds, with inner cycles around 200 nanoseconds.

Most early programming was performed in very amenable and complete assembly code. Some use was also made of a subset of Coral 66 known as Mini-Coral. The 24-bit architecture provided a logical and flexible address/data environment but the 15-bit address limited the memory size to 32K 24-bit words. The operating system allowed multiple programs to run concurrently but most systems were coded "on the bare metal". Addressing allowed easy integration of external computing and display equipment.

In 1964, a Myriad was displayed at a major computer show in London. To catch the public's attention, it was decided to deploy a model HO railroad layout containing numbered (1 - 10) rolling stock. The public were invited to enter the order in which they wanted to see the train assembled. Immediately Myriad developed a strategy for shunting trucks around the tracks to assemble the train correctly.

Marconi's Myriad out-performed most if not all US machines at that time.