e. **John Atanasoff's Binary Computer (1939). **A physics professor at Iowa

State College, Atanasoff built a rough model of a binary-based computer in 1939. He

decided that the ease of representing two symbols instead of 10 in a computer's

circuitry, outweighed the adjustment needed for users in transitioning to the unfamiliar

binary system. The machines, at any rate, could make the conversions without

difficulty.

f. **George Stibitz's Binary Adder (1939)**. A research mathematician at Bell

Telephone Laboratories, he realized that Boolean logic was a natural language for the

electromechanical circuit that could perform binary addition, using the logic of Boolean

gates to control current flow. This device is still a basic feature of digital computers

today.

g. **Stibitz and Williams' Complex Number Calculator. **In 1940, Stibitz and

Williams developed a device that could subtract, multiply, and divide as well as add

complex numbers. The calculator was hooked up to four teletype machines. A nearby

teletype machine transmitted signals to the calculator and received answers from it

within seconds. Two more teletypes in other parts of the building and a fourth 250 miles

away permitted shared access remote control electromechanical computation.

h. **Konrad Zuse's Binary Computer. **Zuse worked independently in Germany,

with no knowledge of Boolean algebra or Charles Babbage's attempts to build a general

purpose computer. He built a binary-based computer that operated on Boolean-like

principles.

i. **John Von Neuman (1945), World War II. **The race for new weapons

speeded up the development of computer theory and design and facilitated progress in

building binary-based computers. John Von Neuman's famous "First Draft of a Report

on evacuation (EDVAC)" (1945) played a key role in spreading the word in the scientific and

scholarly community about the advantages of circuitry designed to handle two digits

(bits) rather than 10.

a. **Simplified Design. **The design of a computer that handled two digits instead

of 10 was infinitely more simplified. Cost was reduced, and reliability improved. Use of

the binary system helped to alleviate modern computers of the "elephantiasis" that had

afflicted the earlier models. The heat, space, and reliability problems that had plagued

the decimal-based EDVAC, for example, were eliminated with the switch to the binary

system.

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