hese machines had punched card or punched tape input/output devices and RAM's of one thousand word capacity. Access times were one-half Greek MU seconds. Some could perform multiplications in two to four MU seconds. Physically, they were much smaller than ENIAC. Some were about the size of a grand piano and used only two thousand-five hundred electron tubes, a lot less than required by the earlier ENIAC. The first generation stored program computers needed a lot of maintenance, reached probably about seventy to eighty percent reliability of operation, and were used for eight to twelve years. They were usually programmed in ML, although by the mid 1950's progress had been made in several aspects of advanced programming. This group of computers included EDVAC and UNIVAC, the first commercially available computers. Early in the 1950's, two important engineering discoveries changed the image of the electronic/computer field from one of fast but unreliable hardware to an image of relatively high reliability and even more capability. These discoveries were the magnetic core memory and the transistor circuit element. These technical discoveries quickly found their way into new models of digital computers. RAM capacities increased from eight thousand to sixty-four thousand words in commercially available machines by the 1960's, with access times of two to three MS (Milliseconds). These machines were very expensive to purchase or rent and were particularly expensive to operate because of the cost of expanding the programming. Such computers were mostly found in large computer centers operated by industry, government, and private laboratories that could staff themselves with many programmers and support personnel. This situation led to modes of operation that enabled sharing of these marvel machines. One such mode was batch processing, in which problems are prepared and then held ready for computation on a relatively cheap st...
