Binary automatic computer

Identification First general-purpose electronic digital computer

Also Known As BINAC

Date Introduced in August, 1949

The development of this early digital computer led directly to modern methods of computation. Although the binary automatic computer was primitive by later standards, even its limitations fueled future advances, as they made clear the initial steps necessary in order to realize the potential of digital computers.

The 1940’s saw the birth of one of the most transformative innovations for future society: the stored-program concept developed by Hungarian American mathematicianJohn von Neumann. Until the late 1940’s, the most advanced electronic computational device was the ENIAC (electronic numeric integrator and calculator), which had originally been built for military calculations. It was used primarily for routine computations, but it had the drawback of operating essentially like an old-fashioned telephone switchboard, with electronic wiring that needed to be reconfigured for each new task.

With the concept of stored programming, which von Neumann published in 1945, it became possible to store separate, simple instructions for one task in a computer’s memory and then combine these instructions with other simple instructions to allow a computer to solve complex problems. For example, one set of instructions could be put in a computer’s memory to tell it to complete long division, and then another set of instructions could be input to complete square-root calculations. These sets of instructions to the computer are called programs and are stored on a physical type of storage medium, such as magnetic tape or a hard disk. The overall type of computer architecture is often called von Neumann architecture. The binary automatic computer uses von Neumann architecture and contains five parts—an arithmetic-logic unit, a control unit, a memory, a tool for input and output, and a bus that provides the path for data to be transmitted among these parts.

The stored-program concept designed by John von Neumann allows instructions that control a computer to be stored in the same memory as the data being manipulated by the instructions. This architecture, sometimes also called the von Neumann machine, was designed to store programs electronically in binary format. Two of the engineers who contributed the most to this digital computer were John W. Mauchly and J. Presper Eckert.

Binary Logic

Due to its dependence on binary logic, the computer that first implemented this stored-program concept as it was envisioned by von Neumann was called the binary automatic computer, or BINAC. Lacking alpha characters, it was totally numeric. It was a bit serial binary computer with a 512-word acoustic mercury delay line memory divided into 16 channels, each of which held 32 words of 31 bits with an additional 11-bit space between words to allow for circuit delays in switching.

Each of these words could hold two instructions, and each of these instructions had a 5-bit operating code and a 3-octal digital address. Pairs of digits were used to match algebraic expressions. Subroutines were stored in memory, and the symbolic code was then used to reference these subroutines. The subroutines were stored in memory, and data was later entered for these subroutines to act upon—a characteristic of the serial access memory used in the BINAC. One difficulty was to make sure that data for the instructions were entered with a sufficient time delay to ensure that the instructions would already be in memory, ready to act on data being entered. Therefore, the engineers converted an IBM 010 keypunch, which had keys for the digits of 0 through 9 and a key for spaces, into an 8-key, octal digit keypad to enter new programs and data. Because there was not enough room in memory for a conversion subroutine to convert between octal and decimal, all of the data entered had to be converted from decimal to octal and then back to decimal, thus producing a time delay.

Developing the BINAC

Mauchly and Eckert began work on this BINAC in 1946 in response to specifications supplied by Northrop Aircraft, which was developing a long-range guided missile system for the U.S. Air Force. Although Mauchly and Eckert had already completed a government contract to build the first digital computer—the electronic numerical integrator and computer (ENIAC)—to complete mathematical computations, ENIAC had relied upon a series of approximately 18,000 vacuum tubes, which required 18,000 valves, measured 24 meters in length, and used punched cards to store data. The BINAC, which used circuits instead of vacuum tubes and magnetic tape instead of punched cards to store data, was a major improvement.

Impact

Upon its completion in 1949, the BINAC could complete several differential equations within fifteen minutes that had previously required two operators using electric calculators a total of six months to complete. The operational speeds for the BINAC were measured in millionths of a second, and this binary logic together with the stored-program concept, which was first implemented in the BINAC, became the foundations of all the computer hardware and software ubiquitous in modern gadgets ranging from cell phones to supercomputers.

Bibliography

Davis, Martin. The Universal Computer: The Road from Leibniz to Turing. New York: W. W. Norton, 2000.

Goldstein, Herman H. The Computer from Pascal to Von Neumann. Princeton, N.J.: Princeton University Press, 1972.

Hally, Mike. Electronic Brains: Stories from the Dawn of the Computer Age. Washington, D.C.: Joseph Henry Press, 2005.

Norberg, Arthur L. Computers and Commerce: A Study of Technology and Management at Eckert-Mauchly Computer Company, Engineering Research Associates, and Remington Rand, 1946-1957. Cambridge, Mass.: MIT Press, 2005.