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Atanasoff’s Computer Japan-Bulgaria Mathematics Meeting — its impact to the present Information Technology Tokyo Metropolitan University Chikara Fukunaga 04.09.2009 1 Contents Japan-Bulgaria Mathematics Meeting • • • • • • 04.09.2009 Overview of Atanasoff’s computer Algorithm used in the computer Logical circuits with vacuum tubes Performance Summary Historical position of the computer 2 Atanasoff’s computer Japan-Bulgaria Mathematics Meeting • 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 Джон Винсент Атанасов (1903-1995) His father was an immigrant from Bulgaria • 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 04.09.2009 3 Japan-Bulgaria Mathematics Meeting Principal structure of Atanasoff’s computer 04.09.2009 4 Synchronization and Control Scheme Japan-Bulgaria Mathematics Meeting • Synchronization has been achieved by a purely mechanical way : electric motor (900rpm) + worm gear (15:1) system 04.09.2009 5 Atanasoff’s Algorithm Japan-Bulgaria Mathematics Meeting • 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 ….. 04.09.2009 x1 6 Japan-Bulgaria Mathematics Meeting Algorithm 2 update of aij • aij=aik – (akk/akj)aij is the principle calculation for both forward and backward akj,j=k..n+1 to Keyboard drum aij,j=k..n+1 to Counter drum • Atanasoff tried to make (akk/akj) with only addition and subtraction 04.09.2009 7 Logical circuit for arithmetic calculation Japan-Bulgaria Mathematics Meeting Atanasoff newly – Introduced logical operation for Arithmetic calculation – devised the following logical table for full adder and subtractor before the switching theory was born Truth Table for 1bit full adder/subtractor – And realized this logic Adder Subtractor in a circuit with vacuum Input Output Output A B Carry X Carry X Carry tubes (tri-poles) and 0 0 0 0 0 0 0 resistors network 0 0 1 1 0 1 1 0 1 0 1 0 1 1 – Eventually established 0 1 1 0 1 0 1 1 0 0 1 0 1 0 the base of present 1 0 1 0 1 0 0 digital computer system 1 1 0 0 1 0 0 04.09.2009 1 1 1 1 1 1 1 8 Logical circuits with vacuum tubes Japan-Bulgaria Mathematics Meeting • 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. High voltage voltage Low ~+V ~0 Vplate (ground) HighLow Voltage Voltage ON OFF 04.09.2009 9 Adder output from NOT,NAND and NOR Japan-Bulgaria Mathematics Meeting • We can construct the Adder output with combination of NOT,NAND and NOR Input • Atanasoff established in this way logic circuits of full adder/subtractor 04.09.2009 Adder Output X Carry Subtractor Output X Carry A B Carry 0 0 0 0 0 1 0 1 0 0 0 1 0 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 1 1 0 1 0 1 1 1 0 1 0 1 10 Performance • Computing time estimation from Japan-Bulgaria Mathematics Meeting A.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 04.09.2009 11 Summary: What did Atanasoff established • Digital electric computation – abandoned to use (old fashioned) analogue computers – brought “digital computation” into the calculation machine system Japan-Bulgaria Mathematics Meeting • 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 control 04.09.2009 12 Japan-Bulgaria Mathematics Meeting Historical position of Atanasoff’s computer 04.09.2009 13 Follow up 1 Japan-Bulgaria Mathematics Meeting Computer programming 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 04.09.2009 14 Follow up 2 Basic hardware structure of a processor Japan-Bulgaria Mathematics Meeting • A typical (simplest) structure will be depicted as 04.09.2009 15 Follow up 3 von Neumann architecture (1945) The following conditions are required to be fulfilled in if a machine is regarded as a modern (universal) computer : Japan-Bulgaria Mathematics Meeting – 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 04.09.2009 16