atanasoff’s computer — its impact to the present information technology tokyo metropolitan...
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Atanasoff’s Computer— its impact to the present Information Technology
Tokyo Metropolitan UniversityChikara Fukunaga
04.09.2009 1
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Contents
• Overview of Atanasoff’s computer• Algorithm used in the computer• Logical circuits with vacuum tubes• Performance• Summary• Historical position of the computer
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Atanasoff’s computer• John Vincent Atanasoff and Cliff Berry developed a computing
machine (Atanasoff & Berry Computer; ABC) to solve linear simultaneous algebraic equations with max. 29 unknowns at Iowa State University in 1940
• Although the machine was for the specific purpose, was neither stored-program architecture nor universal, it is regarded now as the origin of the digital (electric) computer. He was regarded as an inventor of it
• We try to clarify the above reasons through this talk
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Джон Винсент Атанасов (1903-1995)
His father was an immigrant from Bulgaria
Principal structure of Atanasoff’s computer
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Synchronization and Control Scheme• Synchronization has been achieved by a purely mechanical way :
electric motor (900rpm) + worm gear (15:1) system
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Atanasoff’s Algorithm• Forward part – elimination of coefficients of x1 to xn one by one
• With max. 28 pairs (for j=2…29), number of unknowns reduced to 28, and 27,26, … finally we get value of Xn
• Backward substitution using the same algorithm used in forward part
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6….. x1
• aij=aik –
(akk/akj)aij is the principle calculation for both forward and backward
• Atanasoff tried to make (akk/akj) with only addition and subtraction
Algorithm 2 update of aij
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akj,j=k..n+1 to Keyboard drumaij,j=k..n+1 to Counter drum
Logical circuit for arithmetic calculation
Atanasoff newly – Introduced logical operation for Arithmetic calculation – devised the following logical table for full adder and subtractor
before the switching theory was born– And realized this logic
in a circuit with vacuum tubes (tri-poles) and resistors network
– Eventually established the base of present digital computer system
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InputAdder Output
Subtractor Output
A B Carry X Carry X Carry
0 0 0 0 0 0 0
0 0 1 1 0 1 1
0 1 0 1 0 1 1
0 1 1 0 1 0 1
1 0 0 1 0 1 0
1 0 1 0 1 0 0
1 1 0 0 1 0 0
1 1 1 1 1 1 1
Truth Table for 1bit full adder/subtractor
Logical circuits with vacuum tubes
• A combination circuit can be constructed with three logical components NOT, NAND and NOR.
• NOT, NAND and NOR can be realized with a resisters network and one tri-pole tube.
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High voltage
ON
~0 V (ground)Low VoltageLow voltage
OFF
~+Vplate
High Voltage
• We can construct the Adder output with combination of NOT,NAND and NOR
• Atanasoff established in this waylogic circuits of full adder/subtractor
Adder output from NOT,NAND and NOR
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InputAdder Output
Subtractor Output
A B Carry X Carry X Carry
0 0 0 0 0 0 0
0 0 1 1 0 1 1
0 1 0 1 0 1 1
0 1 1 0 1 0 1
1 0 0 1 0 1 0
1 0 1 0 1 0 0
1 1 0 0 1 0 0
1 1 1 1 1 1 1
• Computing time estimation fromA.R.Burks and A.W.Burks “The First Electronic Computer: The Atanasoff Story”, 1988, Univ. Michigan
• Anatasoff estimated time=n3/64 hours if we used a table calculator of that time (1940), and it was 380 hours with n=29
Performance
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Summary: What did Atanasoff established
• Digital electric computation– abandoned to use (old fashioned) analogue computers– brought “digital computation” into the calculation machine system
• Electric switching– used a vacuum tube as a simple on/off switch– implemented Boolean logic (truth table) calculation with vacuum tube
circuits• Memory
– Separated memory from arithmetic operation unit (new architecture)– Chose capacitor as the memory element, and refresh system ( DRAM)– developed Rotary drum memory
( magnetic drum, hard disk)• Sequential control system
– Introduced sequential and synchronization concept for machine control04.09.2009
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Historical position of Atanasoff’s computer
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Computer programming
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Programming sequence of a computer program will be expressed as follows ;– It usually consists of
• Sequential operation• Condition Jump (Branch)• Loop (repetition)
For carrying out such a complicated script, we need various hardware components for a computer– Memory (to store program,
variables and constants )– Arithmetic and Logical Operation Unit– Registers for Arith./Logic Unit and status– Control system
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Follow up 1
Basic hardware structure of a processor
• A typical (simplest) structure will be depicted as
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Follow up 2
von Neumann architecture (1945)
The following conditions are required to be fulfilled in if a machine is regarded as a modern (universal) computer : – Memory access through the address (linear address)– Stored program architecture
• program and data are stored in mix in memory– Program logic dependency
• No distinction between program instructions and data in memory
• Distinction can be made only by the concerned program• If the logic in program is intentionally setup so, the
program can also modify instructions like data– Sequential instruction execution
• A register holds the address of the next instruction to be executed. Instructions are done one by one sequentially
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Follow up 3