Olivetti Programma 101

In 1967, the Programma 101, made by Olivetti, was one of the first successful programmable electronic calculators. Today it can be seen in the Stedelijk Museum of Amsterdam, where it is kept for its outstanding exterior design.

The Programma 101 uses an arithmetic-logic unit built from separate transistors, and a core memory module (using an acoustic delay line memory). There are 10 registers each holding a 22-digit decimal number (in binary-coded-decimal representation!) or a string of 24 instructions. Besides electronics, the P101 has an appreciable amount of sturdy mechanics for its keyboard, built-in printer and magnetic-card reader/recorder. The output was printed on a fast, 30 column drum printer.

The machine's arithmetic operations are -, +, *, /, sqrt, abs. Other operators include data transfer between registers, conditional and unconditional jump. Programs containing up to 120 instructions can be recorded on a magnetic program card. There are extensive program collections for general mathematics, electrical and civil engineering, surveying, statistics, finance, and other disciplines. The size of the machine is 7 × 19 × 24 inches, its weight is 78 lb. The price in 1967 was $3500.

Below a program (adapted from [2]) for calculating and printing n! is shown. In the left hand column the commands are shown as they are entered from the keyboard. The commands are explained by the pseudo-code at the right. Three registers are used: A, M and D.

References:
[1] Adapted from the Computer Museum of the University of Amsterdam

[2] The Olivetti Programma 101 desk calculator. In: C. Gordon Bell (ed): Computer Structures: Readings and Examples. McGrawHill 1971.

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