DEUCE

The DEUCE had 1450 thermionic valves, and used mercury delay lines for its main memory; each of the 12 delay lines could store 32 instructions or data words of 32 bits each. It adopted the then high 1 megahertz clock rate of the Pilot ACE. Input/output was via Hollerith 80-column punch-card equipment. The reader read cards at the rate of 200 per minute, while the card punch rate was 100 cards per minute. The DEUCE also had an 8192-word magnetic drum for main storage. To access any of the 256 tracks of 32 words, the drum had one group of 16 read and one group of 16 write heads, each group on independent moveable arms, each capable of moving to one of 16 positions. Access time was 15 milliseconds if the heads were already in position; an additional 35 milliseconds was required if the heads had to be moved. There was no rotational delay incurred when reading from and writing to drum. Data was transferred between the drum and one of the 32-word delay lines.