Sony SOBAX ICC-400W Electronic Calculator

The Sony ICC-400W was the entry-level machine in Sony's first generation of electronic calculators. There were two models in the initial line of machines, the ICC-400W, and the ICC-500W. In reality, the 400W and 500W calculators were identical in terms of their construction and electronics. The only difference was the addition of a key to the keyboard of the 500W that provides access to a register that accumulates sum of products/quotients. The circuitry for this function is included in the ICC-400W, but it simply lacks the key on the keyboard. It has been verified that the accumulation function is implemented in the ICC-400W by temporarily wiring in a switch in the correct location, and low and behold, the function works. The simple addition of this one key added $200 to the suggested retail price of the ICC-500W -- a prime example of the fairly common practice in the world of consumer electronics, where added features are usually just an addition of an extra switch or display. Such practice is great for manufacturers -- the additional price charged for the feature is nearly all pure profit. In this case, the additional retail charge for the ICC-500W's extra key was $200 in early 1970 -- quite a chunk of 1970 dollars for an additional key switch.

Given that the ICC-400W is so similar to the ICC-500W, I'm not going to bother going into great detail about this particular machine. For detailed information about the construction, features, and operation of the machine, please see the exhibit on the ICC-500W. There is one notable difference worth mentioning between the museum's ICC-400W and the ICC-500W. The 400W has a different connector on the back panel where the external power connector on the ICC-500W is. Sony's first-generation electronic calculators were especially designed to be portable (as made clear by the built-in carrying handle on top of the cabinet), and can operate from a special battery pack, or via an automobile adapter. Sony's calculators were amongst the smallest and most portable calculators of their time, a benefit that made the machines especially suitable for field work. The connector on the ICC-400W, while allowing for connection to external battery power, also provides quite a few additional connector pins that appear to allow an external printer to be connected to the machine. This notion of an external printer interface hasn't yet been substantiated as fact, and is undergoing on-going research.

Closer view of Keyboard & Display

The ICC-400W is a 14-digit, four-function electronic calculator with single accumulating memory register. The machine operates with fixed decimal point location, with the position set by a unique sliding lever situated under the display panel. Simply sliding the lever to the desired location positions to the decimal point at that location. The slide switch has detent positions for each setting, but it is possible to set the switch in "middle" positions that are result in the calculator behaving rather strangely, delivering incorrect answers. The display utilizes Nixie tubes with 5/8-inch tall digits making for easy readability in all conditions. Each tube contains the digits zero through nine, and a right-hand decimal point. The first-generation Sony calculators had a ground-breaking feature for display-type calculators -- leading zero suppression. Unnecessary leading zeroes are inhibited from being displayed, making it easier to read and record the results of calculations. Sony patented this technology, requiring many other calculator manufacturers to pay royalties in order to offer this function on their calculators. An indicator situated to the left of the display lights up to indicate that the number in the display is negative. Another indicator located to the left and above the display lights to indicate an overflow condition.

Profile View of Sony Sobax ICC-400W

The electronics of the first-generation Sony calculators are completely unique, utilizing Sony-made hybrid circuit modules. These modules contain transistors, resistors, diodes, and capacitors placed on an alimina substrate, and then dipped into a compound that dries into a durable and moisture-proof coating for the circuitry. A variety of different modules (each providing different functions) are placed together on circuit boards to create the logic of the machine. The storage element in the calculator is a magnetostrictive delay line. The registers of the calculator are continuously circulated through the delay line, into the calculator logic, and back into the delay line. When the calculator is idle, the calculator logic simply passes the data from the output of the delay line back to the input, while generating the multiplexed display. When operations occur, the logic performs the operations on the bits as they stream out of the delay line, feeding the results back into the delay line.

Given that the ICC-400W is electronically identical to the ICC-500W, performance is the same. The longest calculation, the 'all-nines' divided by one takes just under one second.