Atanasoff’s Computer — its impact to the present Information Technology Tokyo Metropolitan University Chikara Fukunaga Japan-Bulgaria Mathematics Meeting

Contents Overview of Atanasoff’s computer Algorithm used in the computer Logical circuits with vacuum tubes Performance Summary Historical position of the computer Japan-Bulgaria Mathematics Meeting 2

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 Japan-Bulgaria Mathematics Meeting 3 Джон Винсент Атанасов ( ) His father was an immigrant from Bulgaria

Principal structure of Atanasoff’s computer Japan-Bulgaria Mathematics Meeting 4

Synchronization and Control Scheme Synchronization has been achieved by a purely mechanical way : electric motor (900rpm) + worm gear (15:1) system Japan-Bulgaria Mathematics Meeting 5

Atanasoff’s Algorithm Forward part – elimination of coefficients of x 1 to x n 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 X n Backward substitution using the same algorithm used in forward part Japan-Bulgaria Mathematics Meeting 6 ….. x 1

a ij =a ik – ( a kk/ a kj) a ij is the principle calculation for both forward and backward Atanasoff tried to make ( a kk/ a kj) with only addition and subtraction Algorithm 2 update of a ij Japan-Bulgaria Mathematics Meeting 7 a kj, j=k..n+1 to Keyboard drum a ij, 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 Japan-Bulgaria Mathematics Meeting 8 Input Adder Output Subtractor Output ABCarryX X 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 Japan-Bulgaria Mathematics Meeting 9 High voltage ON ~0 V (ground) Low Voltage Low voltage OFF ~+V plate High Voltage

We can construct the Adder output with combination of NOT,NAND and NOR Atanasoff established in this way logic circuits of full adder/subtractor Adder output from NOT,NAND and NOR Japan-Bulgaria Mathematics Meeting 10 Input Adder Output Subtractor Output ABCarryX X

Computing time estimation from A.R.Burks and A.W.Burks “The First Electronic Computer: The Atanasoff Story”, 1988, Univ. Michigan Anatasoff estimated time=n 3 /64 hours if we used a table calculator of that time (1940), and it was 380 hours with n=29 Performance Japan-Bulgaria Mathematics Meeting 11

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 control Japan-Bulgaria Mathematics Meeting 12

Historical position of Atanasoff’s computer Japan-Bulgaria Mathematics Meeting 13

Computer programming Japan-Bulgaria Mathematics Meeting 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 Follow up 1

Basic hardware structure of a processor A typical (simplest) structure will be depicted as Japan-Bulgaria Mathematics Meeting 15 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 Japan-Bulgaria Mathematics Meeting 16 Follow up 3