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Sony ICC-2500W Programmable Desktop Calculator

Sony Sobax ICC-2500W

The Sony Sobax ICC-2500W was Sony's first programmable electronic calculator, introduced on October 22, 1969. It offered 111 steps of program storage, and seven accumulator-style memory registers, and one sum-of-products register, all of which were stored in a magnetostrictive delay line. Magnetostrictive delay lines had the characteristic that when the calculator was turned off or otherwise lost power, the content of the program step storage and memory registers was lost, meaning that the next time a program was needed, it had to be keyed back into the calculator a step at a time. Program steps could be verified using a "Check" mode that allowed stepping through the program memory one step at a time in order to review the steps to assure that the program had been entered correctly. The follow-on machine to the ICC-2500 was the Sony ICC-2550 remedied this problem by adding a magnetic card reader/writer device that allowed the storage and reload of program steps and memory registers on a magnetic card.

The ICC-2500W provides a capacity of fifteen digits, displayed on beautiful Hitachi-made Nixie tubes. The display panel a cover that serves both as ambient light shield when the calculator is being operated, and closes to cover over the display panel to protect the it and the Nixie tubes. The calculator provides the four basic math functions along with single-key automatic square root. The machine provides leading zero suppression, as well as dimly lighting the decimal point to group digits in front of the brightly-lit decimal point in groups of three for easier reading. The machine provides three different digit positions for round-off (0, 2, or 4), with a round-off mode switch that provides for drop, five-up/four-down(5/4), and force up. A [CHG SIGN] key toggles the sign of the number in the display. Decimal point location is controlled by two keyboard switches; [◄∙] and [∙►] that move the decimal point to the left or right respectively.

Programming features provide branching capability and the ability to enter constants as program steps through use of the [D] key before a digit to effectively simulate the depression of a digit key during execution of the program. The double-tall [S] key is used to start or continue execution of a program.

The calculator uses Sony's TTL-like bipolar small-scale integrated circuits for its logic, with 250 of the devices combining with 79 transistors and 117 diodes. The Sony-manufactured delay line provides the storage for the program steps, working registers, and memory registers. The delay line is unusual in that pulses representing the data to be stored into the delay wire are injected using a longitudinal method (push) rather than the usual torsional (twist) method used in most other calculator delay lines. The delay line has a capacity of 320 bits.

Sony states that the calculator performs addition and subtraction in 40 milliseconds, multiplication in 250mS, division in 400mS, and square root on 550mS.

This calculator is wanted in good physical condition, but need not be fully functional.