28 July 2009
IBM Model 1401 Computer
The invention: A relatively small, simple, and inexpensive computer that is often credited with having launched the personal computer age. The people behind the invention: Howard H. Aiken (1900-1973), an American mathematician Charles Babbage (1792-1871), an English mathematician and inventor Herman Hollerith (1860-1929), an American inventor Computers: From the Beginning Computers evolved into their modern form over a period of thousands of years as a result of humanity’s efforts to simplify the process of counting. Two counting devices that are considered to be very simple, early computers are the abacus and the slide rule. These calculating devices are representative of digital and analog computers, respectively, because an abacus counts numbers of things, while the slide rule calculates length measurements. The first modern computer, which was planned by Charles Babbage in 1833, was never built. It was intended to perform complex calculations with a data processing/memory unit that was controlled by punched cards. In 1944, Harvard University’s Howard H. Aiken and the International Business Machines (IBM) Corporation built such a computer—the huge, punched-tape-controlled Automatic Sequence Controlled Calculator, or Mark I ASCC, which could perform complex mathematical operations in seconds. During the next fifteen years, computer advances produced digital computers that used binary arithmetic for calculation, incorporated simplified components that decreased the sizes of computers, had much faster calculating speeds, and were transistorized. Although practical computers had become much faster than they had been only a few years earlier, they were still huge and extremely expensive. In 1959, however, IBM introduced the Model 1401 computer. Smaller, simpler, and much cheaper than the multimillion-dollar computers that were available, the IBM Model 1401 computer was also relatively easy to program and use. Its low cost, simplicity of operation, and very wide use have led many experts to view the IBM Model 1401 computer as beginning the age of the personal computer. Computer Operation and IBM’s Model 1401 Modern computers are essentially very fast calculating machines that are capable of sorting, comparing, analyzing, and outputting information, as well as storing it for future use. Many sources credit Aiken’s Mark I ASCC as being the first modern computer to be built. This huge, five-ton machine used thousands of relays to perform complex mathematical calculations in seconds. Soon after its introduction, other companies produced computers that were faster and more versatile than the Mark I. The computer development race was on. All these early computers utilized the decimal system for calculations until it was found that binary arithmetic, whose numbers are combinations of the binary digits 1 and 0, was much more suitable for the purpose. The advantage of the binary system is that the electronic switches that make up a computer (tubes, transistors, or chips) can be either on or off; in the binary system, the on state can be represented by the digit 1, the off state by the digit 0. Strung together correctly, binary numbers, or digits, can be inputted rapidly and used for high-speed computations. In fact, the computer term bit is a contraction of the phrase “binary digit.” A computer consists of input and output devices, a storage device (memory), arithmetic and logic units, and a control unit. In most cases, a central processing unit (CPU) combines the logic, arithmetic, memory, and control aspects. Instructions are loaded into the memory via an input device, processed, and stored. Then, the CPU issues commands to the other parts of the system to carry out computations or other functions and output the data as needed. Most output is printed as hard copy or displayed on cathode-ray tube monitors, or screens. The early modern computers—such as the Mark I ASCC—were huge because their information circuits were large relays or tubes. Computers became smaller and smaller as the tubes were replaced first with transistors, then with simple integrated circuits, and then with silicon chips. Each technological changeover also produced more powerful, more cost-effective computers. In the 1950’s, with reliable transistors available, IBM began the development of two types of computers that were completed by about 1959. The larger version was the Stretch computer, which was advertised as the most powerful computer of its day. Customized for each individual purchaser (for example, the Atomic Energy Commission), a Stretch computer cost $10 million or more. Some innovations in Stretch computers included semiconductor circuits, new switching systems that quickly converted various kinds of data into one language that was understood by the CPU, rapid data readers, and devices that seemed to anticipate future operations. Consequences The IBM Model 1401 was the first computer sold in very large numbers. It led IBM and other companies to seek to develop less expensive, more versatile, smaller computers that would be sold to small businesses and to individuals. Six years after the development of the Model 1401, other IBM models—and those made by other companies—became available that were more compact and had larger memories. The search for compactness and versatility continued. A major development was the invention of integrated circuits by Jack S. Kilby of Texas Instruments; these integrated circuits became available by the mid-1960’s. They were followed by even smaller “microprocessors” (computer chips) that became available in the 1970’s. Computers continued to become smaller and more powerful. Input and storage devices also decreased rapidly in size. At first, the punched cards invented by Herman Hollerith, founder of the Tabulation Machine Company (which later became IBM), were read by bulky readers. In time, less bulky magnetic tapes and more compact readers were developed, after which magnetic disks and compact disc drives were introduced. Many other advances have been made. Modern computers can talk, create art and graphics, compose music, play games, and operate robots. Further advancement is expected as societal needs change. Many experts believe that it was the sale of large numbers of IBM Model 1401 computers that began the trend.