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Singer/Friden EC1117 Desktop Calculator

Updated 5/24/2021

The 1117 is one of the long-lived and successful line of Singer/Friden 111x-series of desktop electronic calculators. The span of the 111x-series covers four generations of calculator design. The first generation calculator in the line, the Friden 1112 utilized discrete transistor circuitry -- Integrated Circuits simply weren't practical for use in a calculator at the time this machine was designed. The next generation utilized early small and medium-scale Metal Oxide Semiconductor (MOS) Integrated Circuit technology. These machines were the 1113, 1114, 1115, and 1116 models. The third generation machines (the 1117 and 1118) utilized early Large-Scale Integration (LSI) sets of chips. The last generation of the 111x-series were the "A" version calculators (the only currently-known example being the 1117A), which utilized further advances in LSI technology to shrink the chip count from nine chips to only three.

Hitachi's ELCA-42

Like all of the calculators in the 111x-series, the 1117 was designed and manufactured for Singer/Friden by the calculator division of the Japanese electronics giant Hitachi. Hitachi marketed their version of this machine, the ELCA-42, in Asia and Europe. The Hitachi machine was functionally identical to the Friden 1117, but had subtle cabinet and color-scheme differences.

One of the Hitachi LSI IC's used in the Friden/Singer 1117 (Note 1B date code, Feb, 1971)

The 1117 was the "little brother" to the 1118. The 1117 provides twelve digits of capacity (versus fourteen on the 1118), and a single accumulator-style memory register (versus two such memory registers in the 1118). The reduced capability of the 1117 allowed it to sell for $150 less than the 1117, with a retail price of $445.

The Built-In Carrying Handle (stowed and extended)

Both the 1117, 1117A, and 1118 share an identical cabinet base, upper cabinet assembly, mechanical layout, and power supply. Only the keyboard bezel, main circuit board and keyboard assembly make up the differences between the 1117 and 1118. Both the 1117 and 1118 weigh in at 7.7 pounds, and share the same physical dimensions. The 1117, 1117A, and 1118 all have a built-in carrying handle that latches into the bottom of the case and can be folded out for easy portability.

Though the 1117 and 1118 differ in functionality, both calculators are built using the same Hitachi MOS/LSI chip set. Hitachi was among the earliest IC manufacturers in the world to develop successful Large Scale Integration (LSI) Metal-Oxide Semiconductor (MOS) chips, with the initial intention being being to supply Hitachi's own electronic calculator division with cutting-edge chips to shrink the size, improve the capabilities, and most-importantly, to reduce the cost of their electronic calculating machines. The chips that Hitachi's semiconductor division produced were initially used for the calculator division's calculators, but with the calculator market going absolutely berserk, the chips were soon sold to just about every Japanese calculator manufacturer, including Casio, Sharp, Denon(Nippon Columbia), among others. The HD3200-series chip sets represented Hitachi's third generation of MOS integrated circuits targeted at electronic calculating devices, with the first generation being the HD7xx-series of small scale MOS devices; the second generation HD31xx-series, which included some medium-scale integration devices, including the HD3112 serial binary/BCD full adder chip; and the LSI HD32xx-series chips. Both the Friden 1117 and 1118 share a common core of HD32xx-series chips, with two additional chips used in the 1118 that provide the extra capabilities of that model.

Model/Serial Number Tag on the exhibited Friden EC-1117

The common core LSI devices present in both the 1117 and 1118 are the HD3201, HD3202, HN3202, HD3203, HD3205, HD3206, and HD3207. The HD3200-series chips were purposefully designed and built by Hitachi specifically for use in electronic calculating devices. The chips, when combined together in various ways, implement a microcoded engine specialized for performing binary coded decimal (BCD) mathematical operations, ranging from twelve to sixteen digits of capacity, as well as managing the data flow between the various chips. he only chip of these that I have been able to track down any information on at all is the HD3206, which is a general-purpose register chip used for holding the bits that make up the work registers of a calculating machine. The Friden 1117 contains two of these chips, while the upscale Friden 1118 has three of them. The extra chip in the Friden 1118 stores the bits for the 1118's second memory register.

A magnified image of the HD3206 shift register chip

The HD3206 chip appears to contain eight 17-bit shift registers, although it isn't entirely clear how these shift registers are organized. Along with the shift registers, there is some additional logic that appears to provide some data flow control, to allow the bits being shifted through the shift registers to be routed in different ways. The total number of bits of storage in the HD3206 is 136 bits, or enough storage to hold two 16-digit numbers with an extra 17th digit for storing the sign of the number. Each digit is represented by four bits in BCD form. The additional logic inside the HD3206 chip may be used for "skipping over" a set number of bits in the shift registers to allow the chip to store anywhere from twelve to fifteen digits for calculator applications that wouldn't use the full 16 digits worth of capacity in the chip. It can be surmised that the other chips in the HD3200-series likely consist of mask-programmed Read Only Memory (ROM) chip(s) that contain the microcode for a given model of calculator; some form of arithmetic logic unit chip that performs binary coded decimal (and perhaps pure binary) addition and logical operations; a complementer IC that performs BCD (and maybe pure binary) tens and twos complementing for use in subtraction; some form of data routing chip that receives microcode information from the ROM(s) and uses it to control the routing of data from the HD3206 register chips through the calculating logic; and a microcode interpretation and control chip that contains a microcode program counter, microcode latches, and logic that interprets the microcode and sends out control signals to the other chips to orchestrate the execution of microcode instructions. It isn't known at this time which of the chips perform which function, nor even if the guesses as to the partitioning of the logic across the chips is correct. I have not been able to find any kind of specification sheets, functional descriptions, pin-outs, or any other type of documentation for the HD32xx-series chips other than the information presented here. If anyone out there has any documentation on Hitachi's early MOS Integrated Circuits, including the HD7xx, HD31xx-series (though there is some scant documentation posted in the Old Calculator Museum's Technical Informations section, see Hitachi HD3100 PMOS Calculator IC Data sheets), as well as any information on the HD3200-series of chips, please get in touch with the Old Calculator Museum by clinking the EMail button at the top of this page.

Detail showing un-populated Nixie Tube Positions, and Hybrid Display Driver Modules (Black objects below the Nixie tubes)

It is interesting to note that the main circuit board for both the 1117 and 1118 have areas on the circuit boards for a full sixteen Nixie tubes -- clearly indicating that the design was capable of sixteen digits of capacity, but for cost or other marketing reasons, the largest capacity calculator in the Friden 111x-series of calculators was the 1118, with fourteen digits.

Friden 1117 Internal View

Along with the nine LSI chips in the 1117, the machine uses five HD3113 small-scale integrated circuits in Dual-Inline packages as glue logic. The cathodes of the Nixie tubes are driven by a team of three hybrid devices (packaged in black epoxy), while the anodes are driven by discrete transistor driver circuitry. The display uses Hitachi CD-90 Nixie tubes with 1/2-inch digits, and right-hand decimal point.

The 1117 is a fixed-decimal machine, with the decimal point location set by the lower rotary knob on the keyboard panel. The decimal point may be set at 0 through 9 digits behind the decimal point. Overflow occurs if more than the selected number if digits is entered behind the decimal point. A three-position slide switch on the keyboard panel selects the rounding mode of the calculator. The upper-most setting of this switch forces all results to be rounded up at the least significant digit behind the decimal point. In such case, 1 ÷ 3 would result in 0.333334 (with decimal point set at 6 digits), and 2 ÷ 3 would give 0.666667. The middle selection of the rounding switch rounds up or down, depending on the (not displayed) digit behind the least significant digit on the display. If this digit is four or below, the result is left alone. If it is five or above, the result is rounded up. In this case, 1 ÷ 3 would give 0.333333, and 2 ÷ 3 would give 0.666667. Lastly, if the rounding control is set to the lower-most position, rounding is ignored, with 1 ÷ 3 giving 0.333333 and 2 ÷ 3 resulting in 0.666666.

Another rotary knob on the keyboard panel selects various operating modes of the calculator. The switch has four positions. The first position selects no special functions. When the switch is in this position, the calculator operates normally. The second position of the knob selects automatic summing of all results generated by the [+=] key into the memory register. This is useful for calculating averages, sums of products, and other statistical functions. The third position of this switch enables the use of a constant for multiplication and division. The constant is automatically entered when the second number of a multiplication or division problem is entered. Subsequent to the entry of the constant, further calculations with the constant can be performed by entering a first number for the calculation, and pressing the [+=] key to calculate the result. The last position on the mode control knob provides a combination of both the second and third settings...automatic constant on multiplication and division, and automatic accumulation of results into the memory register.

The 1117 uses the same arrangement for display of the sign of the number in the display, overflow, and memory status indication as the 1118 and 1117A. Three small neon indicators are situated at the right end of the display, with labels on the panel that indicate "NEG" (for negative number indication), "UDF" (for "UnDeFined"), which lights up in the event of an error or overflow condition, and "M1", which lights to indicate that the memory register has non-zero content. In the case of an overflow or error condition (for example, division by zero), the UDF indicator lights, and the input from the keyboard is ignored until the [C] key is pressed to clear the calculator.

A Closer View of the Singer/Friden 1117 Keyboard

The keyboard of the machine is quite straight-forward. The keys are made from high-quality black plastic, with molded-in colored nomenclature. The keyboard hardware uses the tried-and-true magnetically-activated reed switches for simplicity and reliability.

The business-end of the 1117's keyboard

The keys are grouped into three areas, with the left-most area controlling overhead functions, such as recalling the memory register to the display [T1] and clearing the memory register [CM], clearing the current entry [CE], and clearing the calculator [C]. The [C] key clears any error condition, and zeroes out the working registers, but leaves the memory register intact. The second group of keys is for numeric entry. The number keypad is organized in conventional fashion, with a double-wide zero key. The [4], [5], and [6] keys have molded-in depressions in them for touch location. The last grouping of keys control the math operations and memory functions of the 1117. The [+=] and [-=] keys are used for adding and subtracting. The [+=] key is also used for finishing multiplication and division operations. The [M1+] key adds the content of the display to the memory register, leaving the display untouched. The [M1-] key subtracts the content of the display from the memory register. The [S1] key stores recalls the content of the memory register to the display, leaving the memory register intact. The [R] key swaps the position of the operands of multiplication and division operations. Lastly, the [X] and [÷] keys are used to inform the calculator that a multiplication or division operation is to be performed.

The 1117 is just slightly faster than the 1118, probably because it has two less digits of capacity to deal with. All 9's divided by one takes about 1/4 second to complete. During calculations the Nixie tubes are left active, but the machine calculates quickly enough that all that is noted is a slight flickering of the digits while the machine is generating the result.

Text and images Copyright ©1997-2023, Rick Bensene.

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