The Computer Know-how (CT) program has been developed to provide coaching in the principles underlying the design of modern pc methods. The 1401 mainframe, the first in the sequence, replaces earlier vacuum tube know-how with smaller, more dependable transistors. Demand known as for more than 12,000 of the 1401 computer systems, and the machine´s success made a strong case for using general-function computers relatively than specialized programs. By the mid-Sixties, nearly half of all computer systems in the world were IBM 1401s.