in March 1948, becoming fully operational by the end of that year.

The Mark II was constructed with high-speed electromagnetic relays instead of the electro-mechanical counters used in the Mark I, making it much faster than its predecessor. It weighed and occupied over of floor space. Its addition time was 0.125 seconds (8 Hz) and the multiplication time was 0.750 seconds. This was a factor of 2.6 faster for addition and a factor of 8 faster for multiplication compared to the Mark I. It was the second machine (after the Bell Labs