Detail map of Philadelphia, Pennsylvania, United States,Hawthorne, California, United States

A: Philadelphia, Pennsylvania, United States, B: Hawthorne, California, United States

Innovative Aspects of the BINAC, the First Electronic Computer Ever Sold

10/1947 to 9/1950

In October 1947 Northrop Aircraft, Inc. of Hawthorne, California, ordered the BINAC (BINary Automatic Computer) from Pres Eckert and John Mauchly’s Electronic Control Company in Philadelphia. The BINAC consisted of two identical serial computers operating in parallel, with mercury delay-line memories, and magnetic tape as secondary memories and auxiliary input devices.

On September 9, 1948 the second module of the BINAC was completed in Philadelphia. Among its numerous innovations were germanium diodes in the logic processing hardware—probably the first application of semiconductors in computers. Until its delivery to Northrop Aircraft in September 1949, the BINAC remained in Philadelphia for use in numerous sales demonstrations.

In February 1949 Albert A. Auerbach, one of the designers of the BINAC CPU at Pres Eckert and John Mauchly's Electronic Control Company, ran a small test routine for filling memory from the A register. This was the first program run on the first stored-program electronic computer produced in the United States. 

On August 22, 1949 Eckert-Mauchly Computer Corporation of Philadelphia issued a press release describing the sale of the BINAC. This was the first press release ever issued for the sale of an electronic computer.

In 2014 it was my privilege and pleasure to handle the only known copy of the first manual ever written for a functioning electronic computer: the Operating and Maintenance Manual for the BINAC Binary Automatic Computer Built for Northrop Aircraft CorporationThis 37-page document, reproduced from typescript by Eckert-Mauchly Computer Corp. in Philadelphia in 1949, was the model for countless numbers of operating manuals for computers that were written in the following decades. As only one BINAC was ever built it is likely that only a handful of copies of the manual were ever produced.

Eckert and Mauchly’s BINAC was the first stored-program computer ever fully operational, since the Moore School’s EDVAC, which was designed to be the first stored-program computer, did not become operational until 1952. The BINAC was also the first stored-program computer that was ever sold.

The BINAC was extremely advanced from a design standpoint: It was a binary computer with two serial CPUs, each with its own 512-word acoustic delay line memory. The CPUs were designed to continuously compare results to check for errors caused by hardware failures. It used approximately 1500 vacuum tubes, making it virtually a mini-computer compared to its predecessor, the large-room-sized ENIAC, which used approximately 18,000 vacuum tubes. The two 512-word acoustic mercury delay line memories were divided into 16 channels each holding 32 words of 31bits, with an additional 11-bit space between words to allow for circuit delays in switching. The clock rate was 4.25 MHz (1 MHz according to one source) which yielded a word time of about 10 microseconds. The addition time was 800 microseconds and the multiplication time was 1200 microseconds. New programs or data had to be entered manually in octal using an eight-key keypad. BINAC was significant for being able to perform high-speed arithmetic on binary numbers, although it had no provisions for storing characters or decimal digits.

In 1946, after developing and building the ENIAC (the first general-purpose electronic computer) for the U. S. Army during World War II, J. Presper Eckert and John Mauchly founded their own company for the purpose of designing and manufacturing electronic stored-program computers on a commercial basis. In October 1947, needing money to keep their business afloat while working on their UNIVAC machine for the U.S. Census Bureau, Eckert and Mauchly entered into a contract with Northrop Aircraft to build the Binary Automatic Computer (BINAC). Northrop, based in Hawthorne, California, was then engaged in a project to build a long-range guided missile for the U.S. Air Force, and had the idea of using electronic computers for airborne navigation; the BINAC, while not designed to work in flight, would perhaps be an initial step toward that eventual goal. Airborne computers did not become feasible until the 1960s, when miniaturized solid-state transistorized components became available.

The BINAC was completed in August, 1949, $178,000 over budget; Eckert and Mauchly absorbed the loss themselves. Built with two serial processors, the BINAC functioned more like two computers than one, with the goal of providing a safety back-up for airplanes. Each part of the device was built as a pair of systems that would check each step. All instructions were carried out once by each unit, and then the result would be compared between the units. If they matched, the next instruction would be carried out; but if there was a discrepancy between the two parts of the machine, it stopped. The processors were only five feet tall, four feet long and a foot wide, tiny for those days. The machine could only do 3,500 additions per second compared to 5,000 on the ENIAC, but it could do 1,000 multiplications per second, compared to only 333 on the ENIAC.

Many histories of computing state that the BINAC never operated successfully; however, Northrop’s “Description of Northrop Computing Center,” an internal company document dated September 16, 1950, which I also handled in 2014, listed the BINAC as one of its three main pieces of computing equipment, and even though the machine was currently “being revised and improved for more reliable operation,” it was still functioning at least somewhat satisfactorily a year after its delivery.

"This machine has solved in seven minutes a problem on the effect of a certain wind pressure on a rubber diaphragm that would have occupied a mathematician for a year. It has solved Poisson’s Equation and obtained a network of 26 solutions in only two hours. For each of these solutions, the BINAC performed 500,000 additions, 200,000 multiplications, and 300,000 transfers of control, all in the space of five minutes. . . . This machine, which is a general purpose computer calculating in the binary system but receiving and emitting its instructions in the octal system, will be demonstrated today on a short test problem (“Description of Northrop Computing Center,” p. 2).

The task of writing the BINAC’s operating manual was assigned to Joseph D. Chapline, an EMCC employee who had helped Eckert and Mauchly on the ENIAC project at the Moore School. Realizing that the BINAC’s users at Northrop would not be electronic computer specialists, Chapline decided to model his BINAC guide on the owner’s manuals issued by automobile companies, rather than on the technical reports written for the Moore School’s ENIAC and EDVAC, which were intended for highly trained engineers and scientists already familiar with the respective machines. Chapline’s Operating and Maintenance Manual provided the BINAC user with a full overview of the machine’s construction, operations and maintenance in a step-by-step, readable manner, with clear diagrams illustrating the BINAC’s various components. Chapline’s instructional, user-oriented approach set the pattern for the millions of computer manuals that would follow it.

Chapline, who also wrote the documentation for the ENIAC, was a pioneer in the field of modern technical writing, which “translate[s] complex technical concepts and instructions into a series of comprehensible steps that enable users to perform a specific task in a specific way” (Wikipedia). Chapline taught over 200 classes in technical writing at the Moore School before leaving the computer profession in 1953 to become the organist and choirmaster at the Unitarian Church of Germantown in Philadelphia. Brockman, From Millwrights to Shipwrights to the Twenty-First Century, ch.7.

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