PERM (computer)

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The program-controlled electronic computing system Munich ( PERM ) is a tube computer that was developed at the Technical University of Munich in the early 1950s .

The computer was jokingly called by the students of the Technical University of Munich (today TU Munich), also referring to its abbreviation PERM: Piloty's First Computing Monster.

It was built from 1952 under the direction of Professors Hans Piloty (Institute for Electrical Communication and Measurement Technology) and Robert Sauer (Mathematics) and put into operation on May 7, 1956, initially in a restricted mode and still without magnetic tape storage. The development team under Piloty and Sauer mainly included Friedrich L. Bauer , Klaus Samelson , Heinz Schecher , Hans-Otto Leilich and Walter Proebster . Among other things, the first ALGOL compiler was developed at PERM .

The main memory of the PERM initially consisted of a drum memory of 8192  words , which was later supplemented by a core memory of 2048 words. The core memory had considerably shorter access times, but apart from that the entire main memory was homogeneous. The memory addresses 0 to 8191 (was always specified in decimal) belonged to the drum memory and from 8192 to 10239 to the core memory. The commands from programs and the processed data could be located in the entire address space, even beyond the boundary between drum and core memory.

The word length was 51 bits, which were structured as floating point numbers : 40 bit mantissa, 8 bit exponent and one bit each sign. The 51st bit, called the Q sign, had a special function, but had no effect on the value of numbers or on the effect of most commands. With a mantissa of 40 bits, the accuracy was roughly in the middle between that of floating point numbers with single and double accuracy according to the standards that later became common. The 10240 words of the main memory corresponded to 40 to 80  KiB on other machine architectures, depending on whether precise numbers are sufficient for the application. Since the memory was addressed word by word, fixed-point numbers occupied a whole word regardless of their value range. The memory requirements of executable programs or texts cannot be compared with other architectures because of the completely different word formats.

In 1974 the PERM was switched off (put to sleep ); it is exhibited today in the Deutsches Museum in Munich .

literature

H. Piloty, R. Piloty, HO Leilich, WE Proebster: The program-controlled electronic computer system Munich (PERM), Nachrichtenentechnische Zeitschrift, 1955, 1st part in issue 11, pages 603–609 and 2nd part in issue 12, page 650– 658

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