Atanasoff’s Computer — its impact to the present Information Technology

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

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

3. Atanasoff’s computer Джон Винсент Атанасов (1903-1995) His father was an immigrant from Bulgaria 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 • 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

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

5. 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

6. Atanasoff’s Algorithm Japan-Bulgaria Mathematics Meeting …..x1 • 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

7. Algorithm 2 update of aij akj,j=k..n+1to Keyboard drum aij,j=k..n+1to Counter drum Japan-Bulgaria Mathematics Meeting aij=aik – (akk/akj)aijis the principle calculation for both forward and backward Atanasoff tried to make (akk/akj) with only addition and subtraction

8. Logical circuit for arithmetic calculation Truth Table for 1bit full adder/subtractor 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 • And realized this logicin a circuit with vacuum tubes (tri-poles) and resistors network • Eventually established the base of present digital computer system

9. Logical circuits with vacuum tubes ~+Vplate High Voltage ~0 V (ground) Low Voltage High voltage Low voltage Japan-Bulgaria Mathematics Meeting ON OFF 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.

10. Adder output from NOT,NAND and NOR Japan-Bulgaria Mathematics Meeting We can construct the Adder output with combination of NOT,NAND and NOR Atanasoff established in this waylogic circuits of full adder/subtractor

11. Performance Japan-Bulgaria Mathematics Meeting • 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

12. Summary: What did Atanasoff established Japan-Bulgaria Mathematics Meeting • 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

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

14. Follow up 1 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

15. Follow up 2 Basic hardware structure of a processor Japan-Bulgaria Mathematics Meeting A typical (simplest) structure will be depicted as

16. Follow up 3 von Neumann architecture (1945) Japan-Bulgaria Mathematics Meeting 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