| +Home | Museum | Wanted | Specs | Previous | Next |
Sony SOBAX ICC-500W Electronic Calculator
Updated 4/14/2024
Sony. The name generally brings to mind all of the wonderful electronics technology that Sony created that we've come to take for granted, such as handheld transistor radios, the WalkMan, DiscMan, PLAYStation, and all manner of high-quality, high-technology, uniquely packaged consumer electronics. Sony's entry into the world of transistorized electronics came to be mostly because the company was the first Japanese company to license transistor technology from Bell Labs. This gave Sony the unique ability to produce their own transistors, which paved the way for Sony to produce many different types of innovative consumer products. One product that doesn't generally come to mind when the name Sony is mentioned is electronic calculators. Sony began participating in the rapidly growing electronic calculator marketplace in 1967, though they'd been developing electronic calculating machines in their research and development labs beginning as early as 1962, and started showing prototype versions of their calculator designs in early 1964. In fact, Sony showed a prototype calculator called the MD-5 at an exposition at the World's Fair (New York City) in March, 1964, the same exposition where Hayakawa Electric (Sharp) introduced their first electronic calculator, the Compet 10. The Sony prototype calculator was in every way technologically superior to Sharp's machine, with a 10-key design versus the full keyboard of the Compet 10, and was significantly more compact and lightweight than Sharp's calculator. However, Sony didn't seize the opportunity to immediately make the prototypes into commercially viable reality. It took Sony almost three years, and a number of successively more complex prototype calculators (MD-6, MM-7, and others, ending with the MX-11, which was the prototype machine behind the ICC-500W), before that company decided to enter the market with their designs, by which time other early entrants to the market, such as Friden, Monroe, Mathatronics, Wang Laboratories and a number of other companies had established a solid head-start. The ICC-500W, was the first of Sony's commercial electronic calculators, was finally introduced to the Japanese marketplace in June of 1967. It took until the early fall of '67 before the ICC-500W was available in North America.
Prototype Sony MD-6 Calculator
Image Courtesy of the National Museum of American History, Kenneth E. Behring Center
It's interesting to note that Sharp is still a major player in today's calculator market, while electronics giant Sony is no longer in the market. It just goes to show that leading-edge technology and beautiful design doesn't always win in the marketplace. Sony didn't really know how to market their technologically advanced calculators, while Sharp had very clearly defined market strategy and tactics. Sony high-level management was always rather skeptical of the consumer viability of electronic calculators, and while they begrudgingly agreed to support a calculator development project, the calculator division really never had all the support it needed to be successful. After remaining in the calculator market until 1973, Sony management realized that the margins on calculator products were diminishing, and the competition in the marketplace had become extremely aggressive. As a result of these pressures, the decision was made to leave the market, and focus the technical resources of the calculator team in other areas.
The SOBAX (which is a name coined from the phrase "Solid State Abacus") line of electronic calculators were Sony's idea of what an electronic calculator should be if done the "Sony Way". And, true to Sony form, the machine is built very well, and performs beautifully. The ICC_500W is constructed on a beefy all-aluminum and metal chassis. Sony was ahead of their time in terms of building a chassis that prevents the escape of radio frequency(RF) emanations from the machine. The chassis completely surrounds all of the electronics, providing an effective radio frequency shield. The high quality molded plastic case is secured by one fastener! Loosening this single captive fastener allows the lower half of the case to be removed. To remove the upper half of the case, a slide latch on each side of the chassis can be activated, freeing the upper half of the case. The power supply makes up the back section of the chassis, and while it is tethered to the rest of the electronics by a ribbon cable, it is on slides. Once two retaining pins are removed, and tension taken off of clips that retain the power supply module, the power supply can be slid out of the chassis. There's enough extra length in the power supply ribbon cable that the power supply can be moved far enough away to gain access to the five circuit cards that make up the brains of the machine. The circuit boards are very high quality double-sided boards with plated-through holes, surrounded with a heavy aluminum stiffener on three sides of the board. The boards plug into a hand-wired backplane that interconnects the boards to each other, and to a separate circuit board which handles the decimal point selection logic and display driving functions.
The SOBAX sans cabinet, with power supply module slid out
A unique feature of the first-generation Sony SOBAX calculators was the provision for the machines to be powered by sources of power other than the AC power line. The BP-11E battery pack provided an external rechargeable battery pack that would operate the calculator independent of AC power. The DCC-2AW auto power adapter would allow the SOBAX to be powered from the cigarette lighter outlet of an automobile. These external accessories were plugged into a special power connector located on the back panel of the machines. This aspect gave the calculators a feature that no other calculator on the market at the time had, the ability for the calculator to be used in the field rather than being tethered to a desktop by the AC power cord.
This particular example of the ICC-500W
hails from the late 1968 time frame, based on date codes on devices in the
machine. This SOBAX calculators come from a time before
Sony had production capabilities to make integrated circuits. Sony already
had large-scale production facilities for hybrid circuit modules that it
used in its other products, and it was less-expensive for Sony to use their
existing hybrid circuit technology rather than buy integrated circuits from domestic
or overseas IC manufacturers. The ICC-500W, and its stable mate, the
ICC-400W, are made using special versions of Sony's hybrid circuit modules.
Hybrid circuits were a bridge technology between individual
discrete components and later integrated circuit technology. In these
hybrid modules, an substrate material made from Aluminum Oxide is printed with circuit traces,
and film resistors. Attachment pads for miniaturized components such
as diodes and capacitors are also printed on the substrate, as well as tiny
bonding pads for transistors. The transistors are packaged in an epoxy case, with the three
leads connected to the pads on the substrate. Wire leads
extend from the bottom edge of the substrate to provide connections to the module.
The assembly is tested to assure it works properly, and is then dipped in a
durable insulating compound that hardens to protect the components and seal out
moisture. The hybrid circuit is tested again, and if it passes, it is ready for use.
A close-up View of some of the Hybrid Circuit Modules
The Circuit Board Cage (note delay line in metal enclosure at bottom of chassis) The SOBAX ICC-500W is a 14-digit, four function electronic calculator with
memory. It uses Nixie tube display technology, with each Nixie tube containing
the digits zero through nine, with a decimal point at lower right.
The calculator uses a magnetostrictive delay line, located in
the base of the chassis to store the five working registers of the calculator.
Two registers are used as the main working registers of
the calculator, one register serves as a temporary register used during
multiplication and division operations, one register contains the memory register,
and another register is used for the summation accumulator. The delay line contains a total of
360 bits of storage, which is equivalent to six registers of fifteen binary-coded decimal
digits (four bits per digit). The sixth register is not used by the calculator for
math operations, but contains a pattern of bits that are used by the calculator
to synchronize the delay line with the calculator's logic. Each register consists of
fifteen binary-coded decimal digits(four bits for each digit), with the extra digit
used to store the sign of the number. The delay line has a delay period of 1.5 milliseconds
(.0015 seconds), with the bits represented as a chain of torque pulses in a coiled wire that
is three meters in length, contained in a metal enclosure located in the base of the calculator.
The ICC-500W operates in fixed decimal point mode, with a long slide switch
that extends below the width of the display panel. The slide switch can be set to
any desired decimal point position, and the calculator will take care of
assuring that it will be located at that position. This allows
a setting from zero to thirteen digits behind the decimal point. The machine
has a memory register which is operated by the [M IN] key (somewhat of a misnomer,
as the key actually adds the content of display to the memory register). The [M OUT]
key recalls the content of the memory register to the display. The
[M C] key clears the memory register (without affecting the display). The
memory register is stored in the delay line along with the rest of the
operating registers of the machine, meaning that the content of the
memory register is lost when power is removed.
One of the five circuit boards that make up logic of the calculator The [R] key serves as an exchange key,
allowing easy swapping of dyadic operands, particularly useful for
swapping the dividend and divisor in division problems. The large [CLEAR]
key serves as a clear-all function, clearing the machine
(except for the memory register) and canceling any overflow
condition. The smaller [C] key serves to clear the display register to allow
for correction of input errors. The red [T] key is unusual.
This function allows for accumulation of products and quotients, and acts as
separate accumulator storage register. This is a push-on/push-off key, which
when depressed, activates the accumulation function, with the result of
any multiply or divide operations automatically added into a non-displayed accumulator
register, separate from the memory register. The accumulation of products/quotients
continues until the [T] key is pressed again to release the key, and turn the function off,
at which time the content of the accumulator is recalled to the display, and the accumulator
register is cleared.
A closer view of the Sony SOBAX keyboard and display The display panel has two annunciators at the left end of the display,
which are illuminated by neon tube indicators behind small jewels. An overflow
condition lights up an annunciator clearly stating "OVER FLOW", and logically locks out
the keyboard to all but a press of the [CLEAR] key. A negative sign indicator
lights to indicate when the number in the display is negative. The
calculator doesn't know how to deal with division by zero. Doing so will
cause the machine to go into a spin, which results in every digit in each
of the Nixie tubes being lit at once -- the machine is looping forever trying
to calculate the impossible. A press of the [CLEAR] key halts this behavior,
returning the machine to normal.
A Detailed view of the Nixie tube display (showing the "OVER FLOW" indicator) A slide switch on the keyboard
panel selects the rounding mode of the machine, with the rounding function
again showing Sony's independence of thought with regard to how rounding
should work. The rounding function occurs on the 3rd digit from the
right end of the display...no matter where the decimal point is positioned.
If this digit is 5 or greater, the next significant digit is incremented, and
the remaining two right-most digits cleared. If the digit is 4 or less,
the rightmost three digits of the display are cleared.
What occurs when division by zero is attempted The display is not blanked during calculation, and spin pretty
dramatically during longer calculations. The machine benefits from
leading zero suppression on
display, and leading/trailing zero suppression on input, which, for a machine
of the time, is a very advanced feature, and very uncommon on machines of
this era. It appears that Sony invented the notion of leading-zero suppression
on display-type calculators.
A view of the back side of the keyboard assembly The keyboard on the SOBAX uses the commonly used technology of magnetically
activated reed switches, but adds a Sony twist. Each key is an individual
module, with the key-stalk and magnet, reed switch, and key return spring
enclosed in a plastic housing. Two wires exit the housing providing connections
for the reed switch. The housings are retained in the keyboard panel with
small spring clips. This makes it quite a simple operation to replace a
defective key, though again, being as Sony did it their way, it makes it
more difficult for future preservationists to provide replacements should any
of these parts fail. Fortunately, though, these switch modules seem to be
very robust and reliable.
The ICC-500 performs reasonably well, with published performance
figures of 15 milliseconds for addition and subtraction, 250 milliseconds
(1/4 second) for multiplication, and 400 milliseconds for
division. Actual experience with the calculator bears out these figures, except
in the case of the museum's worst-case division benchmark, dividing a full
register of 9's by one (in this case, 99999999999999 divided by 1), which
takes just under one second to perform. Published performance figures
were typically averages, which explains the discrepancy, as typical divisions
certainly do complete in less than 1/2 second.
