<P> After the 1920s, the expression computing machine referred to any machine that performed the work of a human computer, especially those in accordance with effective methods of the Church - Turing thesis . The thesis states that a mathematical method is effective if it could be set out as a list of instructions able to be followed by a human clerk with paper and pencil, for as long as necessary, and without ingenuity or insight . </P> <P> Machines that computed with continuous values became known as the analog kind . They used machinery that represented continuous numeric quantities, like the angle of a shaft rotation or difference in electrical potential . </P> <P> Digital machinery, in contrast to analog, were able to render a state of a numeric value and store each individual digit . Digital machinery used difference engines or relays before the invention of faster memory devices . </P> <P> The phrase computing machine gradually gave way, after the late 1940s, to just computer as the onset of electronic digital machinery became common . These computers were able to perform the calculations that were performed by the previous human clerks . </P>

Who is credited with the invention of the modern perspective system