The first UNIVAC computer was delivered to the Census Bureau in June 1951. Unlike the ENIAC, the UNIVAC processed each digit serially. But it’s much higher design speed permitted it to add two ten-digit numbers at a rate of almost 100,000 additions per second. Internally, the UNIVAC operated at a clock frequency of 2.25 MHz, which was no mean feat for vacuum tube circuits. The UNIVAC also employed mercury delay-line memories. Delay lines did not allow the computer to access immediately any item data held in its memory, but given the reliability problems of the alternative Cathode Ray Tube (CRT) technology, this was a good technical choice. Finally, the UNIVAC had placed strong emphasis on its input/output capabilities, being designed specifically for data processing applications such as that of the Census Bureau. In this connection, EMCC had developed a digital magnetic tape recording unit that could deliver data to the UNIVAC at a rate of 40,000 binary digits (bits) per second. For a brief period, Univac had captured a majority of the market for digital electronic computer systems.