Electric Dreams: Computers in American Culture

2: Ideologies of Information Processing: From Analog to Digital

Ideologies of Information Processing From Analog to Digital So far, I haven’t discussed how a computer processes information in much detail. In this chapter, I want to turn to this more technical subject, to look at the ideological conflicts underlying a critical transformation in information processing: the shift from analog to digital, which began in the 1940s and 1950s, and which continues to this day. Instead of the proliferation of Babbage’s digital computing devices, the nineteenth century saw the slow development of more limited calculating machines. The cash register was invented in 1879; by the turn of the century , it was used by most store owners in the United States.1 In 1890 the U.S. Census Bureau hired Herman Hollerith to design a machine capable of collating demographic information about millions of people. Hollerith designed a system in which each person’s demographic information was stored on an individual punch card. His successful company would ultimately change its name to International Business Machines, or IBM for short. By the 1920s and 1930s, scientists were designing more sophisticated machines to handle more complex mathematical questions. The most famous of these was the differential analyzer, built by Vannevar Bush and his students at MIT in the 1930s. While many machines of this era were developed to calculate only specific equations, the differential analyzer was designed to be a more flexible machine. As Campbell-Kelly and Aspray write, it could address “not just a specific engineering problem but a whole class of engineering problems that could be specified in terms of ordinary differential equations.”2 Machines such as the differential analyzer were in many ways what we would now call “computers.” But most histories of computing pass 2 35 quickly over these devices, treating them as a wrong turn in the development of computing technology.3 That’s because, unlike Babbage’s devices, these were analog machines. Not until the era of World War II were the first digital computing devices successfully built. The transition from analog to digital after World War II (or, to put it another way, the return to Babbage’s digital conception of computing) was a critical point in the history of computing, and the distinction between analog and digital continues to be a crucial—and ideologically loaded—concept in contemporary computing culture. Analog and Digital Let’s start by clarifying the two terms. This useful distinction comes from Stan Augarten’s Bit by Bit: [D]igital and analog . . . describe different methods of counting or measuring various phenomena, and the distinction between them is best illustrated by two gadgets that are found in almost every car: a speedometer and an odometer. As a recorder of miles traveled, an odometer is a digital device, which means that it counts discrete entities; as a measurer of miles per hour, a speedometer is an analog device, because it keeps track of velocity. When we count things, regardless of what those things may be, we are performing a digital operation—in other words, using numbers that bear a one-to-one correspondence to whatever it is we’re enumerating. Any device that counts discrete items is a digital one. By contrast, when we measure things, whether to find their weight, speed, height, or temperature, we are making an analogy between two quantities . Any gadget that does this is an analog one. Scales, rules, speedometers , thermometers, slide rules, and conventional timepieces (the kind with hands) are all analog instruments, whereas odometers, . . . mechanical calculators, and the overwhelming majority of electronic computers are digital devices.4 Digital computers process information through mathematical calculations , following set, clearly defined rules (called “algorithms”), just as humans do when calculating with pencil and paper. The way in which analog computers process information is more difficult to explain. Here’s Herman H. Goldstine’s The Computer from Pascal to von Neumann: 36 | Ideologies of Information Processing [A]nalog machines depend upon the representation of numbers as physical quantities such as length of rods, direct current voltages, etc. . . . The designer of an analog device decides which operations he wishes to perform and then seeks a physical apparatus whose laws of operation are analogous to those he wishes to carry out. He next builds the apparatus and solves his problem by measuring the physical, and hence continuous , qualities involved in the apparatus. A good example of an analog device is the slide...