SAPO A five-address computer and the ease of programming

DURNOVÁ, Helena. SAPO A five-address computer and the ease of programming. In Turing in Context II. 2012.

Basic information

• Original name: SAPO A five-address computer and the ease of programming
• Authors: DURNOVÁ, Helena.
• Edition: Turing in Context II, 2012.

Other information

• Original language: English
• Type of outcome: Presentations at conferences
• Field of Study: 60101 History
• Country of publisher: Belgium
• Confidentiality degree: is not subject to a state or trade secret
• Organization unit: Faculty of Education
• Keywords in English: SAPO computer; Antonín Svoboda (1907-1980); history of computing in Czechoslovakia

Abstract

The first Czechoslovak general purpose computer SAPO (acronym from SAmočinný POčítač, i.e. automatic computer) was put into operation in 1957 after almost a decade of refinements of the basic idea. It was a relatively slow computer, but its chief designer, Antonín Svoboda (1907-1980), defended the speed claiming that the spead of the individual operations is not as important a factor as the number of tasks that can be computed on the computer in a given period of time SAPO had three arithmetic units to avoid mistakes in calculations by performing the tasks in parallel on the three units and checking after each individual step, repeating the faulty calculations and stopping only when the same mistake occurred twice in a row. Finally, SAPO was a five-address computer: in each instruction, the first two addresses were for the operand, the third for storing the results, and the last two determined where the next instructions are to be found in case of positive and non-positive results of that particular operation. Although Svoboda only met Turing once (in 1947), his design of a computer concentrated on leaving all tasks possible to the computer. As a result, programming SAPO was so comfortable that it did not require the use of automatic programming methods: most of the mechanizable tasks were already left to the computer. In my talk, I will concentrate on Svoboda's justification of the special features and on the reasons behind their use.