Transcript Document

Atanasoff’s Computer
Background
• In 1932 Vannevar Bush of the Massachusetts Institute of Technology
completed a mechanical computer called the differential analyzer
which did caculus by rotating gears and shafts
• Electronic computers operate primarily by means of such electron
devices as vacuum tubes, transistors or, now microchips; electrons,
rather than computers parts do most of the moving
• The first electronic computer was generally agreed to be the Colossus,
build by Alan Turing and M.H. Newman at the Bletchey Research
Establishment in England. 1943.
• The late recognition of Atanasoff’s computer was discovered due to a
lawsuite initiated in1967 between Sperry Rand Corp and Honneywell
Inc. Sperry had bought the patent to the ENIAC and was charging
royalties. Honeywell v. Sperry Rand
• Judge Earl R Larson, sated “ Mauchly and Eckert did not themselves
first invent the automatic electronic digital computer, but instead
derived that subject from Dr Jhon Vincent Atanasoff” (This made
Atanasoff’s creation be classified as the earliest know electronic comp)
Background Cont’t
• Winter of 1937 Atanasoff had decided on a few principles for the
computer:
– The storage of data should be separated from the computational function
– the method of computation should be digital rather than analog
– The machine would express numbers as digits rath than by analogy to
some physical quantity (such as the distance along the axis of a slide rule)
– Calculations in terms of bases other than base 10
• He resolved to rely on electronic switches (electric decses that direct
the flow of electical signals) rather than mechanics to carry out the
comps control and arithmetic functions
• Binary numbers would act on those numbers by following rules of
logic instead of direct counting
• A positive charge on one end of a capacitor could represent the number
1, and no charge could stand for 0
Prototype
“Abacus”
Driving Force
• Iowa State College
1930s
• JVA on Physics faculty; looking for ways to
simplify his calculating burden
– did a study of existing computing equipment in 1935
and 1936; experimented with using 30 Monroe
calculators on a common shaft; knew of the Bush
Differential Analyzer at MIT
• modified leased IBM punched card equipment,
much to the consternation of IBM salesman
Solve for N
• He wanted to solve n equations with n unknowns
(specifically 29)
29 x 28 x 27 x 26 x25 x 24 x 23 x 22 x 21 x 20
x 19 x 18 x 17 x 16 x 15 x 14 x 13 x 12 x 11
x 10 x 9 x 8 x 7 x 6 x 5 x 4 x 3 x 2 x 1
( n * n-1) / 2 or (29 * 28)/2 = 406 iterations
Problems/Solutions
• Initially working on the project his thoughts did not “Jell” and he
became distressed because of this.
– Took a drive (at high speeds) focusing on driving. After 200 or so miles
stopped at a road house to get a drink.
– Atanasoff appreciated that the mind needs variety and relaxation in order
to perform creatively. Having conceived of some fundamental principles,
he then allowed “a kind of cognition” to come into play.
– Such a reliance on intuition may not be in accord with the common
perception of scientific investigation as a strictly rational activity
• Capacitors have a tendency to lose their charge.
– Regenerating the memory, a process called “jogging” would restore the
charge in a capacitor so that if the capacitor was in say the plus state, 1, it
would remain that way. This would stop the change/decay to 0 over time.
• The punch-card input-output systems generated an error about once
ever 10000 punching and reading operations in the ABC
• Only raised $6,000 to fund and work on this system
– Compared to ½ million for the ENIAC, which was given military funding
Contributions
• Comparing the ABC with Bush’s differential analyzer
– ABC attained an accuracy that was 1000 times greater than was possible
with the differential analyzer
– The precession could easily increased more if needed by adding more
digits. Compared to analog where it is difficult and expensive.
• Store his binary digits in capacitors due to cost and could send signals
to the computational unit with out their having to be amplified
– He considered vacuum tubes and ferromagnetic materials
• Developed a logic circuit (Black Box)
– Build out of vacuum tubes and would receive signals from the capacitors
in the memories.
• The capacitors were called keyboard abacus and counter abacus
– Logic circuits today are stored in chips that are much faster than vacuum
tubes but perform basically the same functions
Contributions Con’t
• He could have claimed to have come up with the concepts of:
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Electronic digital computation
Electronic switching in computers
Circuits for logical addition and subtraction
Separation of processing from memory
Capacitor-drum memories
Memory regeneration
Use of the binary number system in electronic computing
Modular units
Vector processing
Clocked control of electronic operations
ABC Parallel Machine?
• His system had one logic circuit, consisting of seven tubes, added or
subtracted the coefficient, in the keyboard to or from the coefficient in
the counter, leaving the sum or difference in the counter
• At the same time the other circuits processed the other pairs of
coefficients in the same way. (this process which a number of
operations are performed in parallel, is called vector operations, and
computer carrying out such operations is a vector processor
– A vector processor, or array processor, is a CPU design that is able to
run mathematical operations on multiple data elements simultaneously
– Parallel computing is a form of computing in which many instructions
are carried out simultaneously. Parallel computing operates on the
principle that large problems can almost always be divided into smaller
ones
Architecture of ABC
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1. Separate memory and computation
2. Digital (rather than analog)
3. Electronic switches
4. Binary number system
5. Calculate by logic nor counting
6. Memory required “jogging”
7. Capacitor for memory (ICs today)
8. Modular units
9. Vector processing
10. Control by a clock
ABC vs ENIAC
• ENIAC was the first general purpose electronic computer
• ENIAC could be programmed for different problems by altering the
configuration of wires plugged into a control panel
• ENIAC calculated by direct counting and it did so in base 10
• ENIAC had thousands of vacuum tubes and it memory was electronic
• ABC Was designed to be a special purpose machine
• ABC calculated by logic and it did so in base 2
• ABC had hundred of vacuum tubes and its memory was on rotating
drums
• Both used electronic switching to control the operations of the
computer
• Both had the idea that digital electronic machines could do calculus
with greater precision and speed than Bush’s differential analyzer
Resources
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file:///C:/Documents%20and%20Settings/dmoshier/Local%20Settings/Temporary%20I
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