It used only 150 watts of power, an astonishingly low figure in an era when machines typically used tens of kilowatts to warm their valves.
The expanded 1955 machine had a total of 200 point-contact transistors and 1300 point diodes,[1] which resulted in a power consumption of 150 watts.
There were considerable reliability problems with the early batches of transistors and the average error free run in 1955 was only 1.5 hours.
Metropolitan-Vickers became interested in the design after the success the university had selling computing time on the Mark I to commercial customers.
The only relevant experience in Metropolitan-Vickers was that in the early 1930s they had manufactured a mechanical calculating machine in the form of the differential analyser in conjunction with Douglas Hartree of Manchester University.