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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.