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Singer/Friden 1162 Desktop Calculator

Updated 4/22/2019

The Singer/Friden 1162 was developed as an integrated circuit-based remake of Friden's first-generation all-transistor electronic calculator, the Friden EC-132. Introduced in May of 1969, less than a month after the introduction of the Friden 1160. The 1162 benefitted from the use of integrated circuits to rather drastically reduce the size, weight, power consumption, and most importantly, cost. The 1162 was over $750 less expensive than the Friden 132 when it was introduced, and at an introductory price of $1,195, the 1162 was quite competitively priced versus competing calculators from other makers.

Model Identification Tag on Exhibited Singer/Friden 1162

The museum has three examples of the 1162, one fairly early production machine made in the summer of 1969, and the other two machines built in the latter part of 1969, with these dates based on date codes on various parts of the machines. The exhibited calculator has serial number 2265 There seems to be few, if any detectable differences between the early machine and the later machines, other than the obvious variations in component vendors. The component differences are due to the fact that inventories of components at the manufacturing plants were kept to a practical minimum due to the cost of maintaining inventory. Components were ordered from vendors as-needed from manufacturer's reps, with Friden getting the best deals on the components that their reps could get. The component mix could vary from one machine to another, even those one serial number apart, simply due to the mix of parts available to the people on the circuit board line who stuffed the components into the circuit boards.

Inside View of Singer/Friden 1162

The 1162 shares the Cathode Ray Tube (CRT) display technology used in the earlier 130/132 calculators, but uses a smaller CRT (Westinghouse Type 3WP1), and dispenses with the display of the upper two levels of the four-level RPN(Reverse-Polish Notation) stack due to the limited size of the display. The bottom two registers of the stack are displayed on the tube, leaving the top two registers of the stack invisible. The smaller CRT further helped to reduce the physical size (and weight) of the calculator.

Close-up of 1162 CRT Display

The digits are drawn on the CRT in a slightly different fashion than the earlier 130/132 calculators, but the display is pleasing to the eye, and is easy to read, even in bright office lighting. A major difference between the 1162 and 1160 calculators and the first-generation machines is that the digits on the display are grouped in threes (except while entering a number) to make reading and recording results easier for the operator. Oddly, though, the bottom register of the stack, where numbers are entered, does not group the digits in threes, nor is the decimal point displayed as numbers are being entered. For example, entering 65.536 shows up on the bottom line of the display as "00000000065536" (note no decimal point) until the [FIRST NUMBR/CHG SIGN] key is pressed, then the digits become grouped in threes and the decimal point is displayed in the selected position. This blind input of numbers without the decimal point being displayed takes some faith, as the user must trust that when the decimal point key is pressed, it is indeed being recognized.

The intricate mechanical keyboard encoding mechanism

The 1162 provides the standard four functions and square root (with the [√] key replacing the [X+] key of the 1160), along with a store/recall memory register. The machine has a capacity of 14 digits plus sign, one more digit than the Friden 132 it was patterned after. Decimal point location is fixed, and is set by a rotary thumbwheel that allows selection of decimal point location from 0 to 11 digits behind the decimal point. The keyboard is a miniaturized and somewhat less robust version of the very smooth, yet complex, mechanically encoded keyboard used on the first-generation Friden electronic calculators. Like the earlier machines, when a key is pressed, it is mechanically locked in the depressed position until the operation is completed by virtue of a solenoid-activated mechanism. For very fast operations, such as digit entry, the period the key is locked is so short that it isn't really noticible. However, for longer operations such as square root, the delay is definitely apparent. During the time the operating key is locked down, the remainder of the keys with the exception of the [CLEAR] and [CLEAR STACK] keys are physically locked from being depressed, to keep the operator from operating keys while the machine is still busy. For a fast operator, this may require some time to get used to. The 1162 gives up the combination [OVERFLOW/LOCK] key of the first-generation Friden electronic calculators, opting instead for an indicator labeled "OVERFLOW" on the keyboard panel that lights to indicate an overflow condition, and use of the [CLEAR STACK] key to unlock the keyboard and clear the machine when an overflow occurs.

The Circuit Boards Used in the Exhibited Friden 1162 (Click on image for larger view and more details about the board)

The 1162 uses off-the-shelf bipolar small-scale integration IC's for most of its logic. The majority of the chips found in the 116x-series calculators are made by Texas Instruments(TI), and are from the company's Diode-Transistor Logic (DTL) SN158XX family. While many of the TI chips are used, equivalent DTL devices from Fairchild(DTµL 99xxxx-Series) and Motorola(MC8xx-Series) are also used here and there. Along with the DTL devices, there are also a number of newer-technology TTL (Transistor-Transistor Logic) devices from what became the ubiquitous 7400 family, developed by TI and eventually made by just about every American chipmaker under license from TI. Most of the TTL chips are 7473, 7474 or 7476 dual-flip flops, with a few other 7400-series devices in the mix. Most of the TTL devices are made by Texas Instruments, with parts from Signetics also used.

The Custom Counter Chips (SN1286="A" Counter, SN1287="C" Counter, SN1288="D" Counter)

Along with the off-the-shelf ICs, the 1162 uses a number of custom bipolar TTL ICs manufactured by Texas Instruments for Singer/Friden. One set of these custom chips is located on the arithmetic-logic unit (ALU) circuit board (Board #3). The chips have part numbers SN1286, SN1287, and SN1288. Each chip provides the function of one of the three switch-tail ring counters used in the "three-counter" architecture of the Friden 130/132, whose basic mathematical architecture carried forward to the 116x-machines. Each of these chips replaces what amounts to a handful of discrete transistors, capacitors and resistors used in the first-generation Friden electronic calculators.

The Custom NAND-gate Chips Used on Board 1

Along with the three custom chips used on the ALU board, there is another custom chip used on board #1, which contains the circuitry related to the generation of the display. This chip was made by Texas Instruments for Singer/Friden, and has part number SN9095. This chip is used twice, and the two chips are the only integrated circuit devices on the board, with the remaining circuitry implemented with discrete components. Board #1 was the only board that was used across all of the models in the 116x-series calculators.

Mysterious Custom Counter IC's Found in a Friden 1162 Built in the latter-part of 1969

A mystery surrounds some unusual chips found on Board #3 in some 116x-Series calculators. One of the museum's Friden 1162's, as well as the museum's 1166, have different counter ICs. Instead of the Texas Instruments-made black-plastic packages with a notch in one end of the package for pin 1 indication, as well as silver-plated Kovar leads, Board #3 in one of the 1162s has two of the counter chips with light-blue plastic packages and a raised dot indicating pin 1, and gold-plated leads. One device, with a part number of 811786 (equivalent to the TI SN1286), has both "SINGER" and "Friden" text logos with a date code of 6915 (15th week of 1969) printed in black. The other device, used in place of the TI SN1288, has only the Friden text logo, with part number 811788 and a date code of 6905. The museum's Friden 1166 also contains one of the 811788 chips with a date code of 6906 (6th week of 1969). It is a mystery as to who manufactured these chips. Singer Company, with a long history of work in the aerospace industry, is not known to have its own integrated circuit fabrication facilities. Friden, before Singer purchased the company in 1963, had established a world-class R&D facility in Oakland, California that was known to have developed some IC fabrication capabilities, but the facilities were more for research and development rather than volume IC production. Perhaps Friden's R&D facility created small quantities of these chips used for early production 116x-series calculators until Texas Instruments was able to provide production quantities of the counter ICs. At this point, that is only supposition, and for now, these chips remain a mystery. Perhaps someone reading this exhibit will recognize these chips, and will write to the museum (click the EMail button at the navigation bar at the top of this exhibit page) and will shed some light on this mystery.

The 1162 utilizes a total of 93 IC's, along with a significant number of transistors, diodes, resistors and capacitors. The main logic of the machine is spread across six circuit boards (one more than the 1160 and 1166) which are situated vertically in a card cage, plugging into a backplane made from an etched circuit board, with gold-plated edge-connector sockets that the circuit boards plug into. The backplane board also contains some of the power supply circuitry, mainly the generation of the high voltage (3KV) used by the CRT. An additional circuit board mounted aside the CRT provides the analog circuitry that drives the CRT display, including deflection amplifiers and electron beam drive circuitry.

The Delay Line (in aluminum housing) and Delay Line Driver/Amplifier Board

Even though IC's replaced the discrete transistor electronics of the earlier 130/132 machines, the 116x-series machines, including the 1162, still use magnetostrictive delay line technology for storing the working registers of the calculators, including the four level stack and the memory register. The delay line of the 1162 is contained in a sealed aluminum housing in the base of the machine, as in the 130/132, but the whole assembly is significantly smaller that its counterpart in the 130/132. The delay line in the 116x-series machines is simplifed in design from that used in the 130/132 calculators, with less mechanically complex transducers and simplified driver circuitry. The delay line material is a Beryllium-Copper alloy wire approximately 40-feet in length, with a smaller wire diameter than that used in the 130/132 calculators, allowing the overall delay line package to be about two-thirds smaller in volume than the 130/132 delay line. The delay line in the 116x-series calculators has a delay period of approximately 4 milliseconds.

Inside a Friden 116x-Series Delay Line

The delay line was still needed, as the use of the four-level Reverse-Polish stack architecture, first used in the Friden 130, simply required too many bits of storage to be economically implemented with off-the-shelf bipolar IC technology of the late 1960's.

Friden 116x-series delay line transducer and magnetostrictive tapes connected to delay line wire

For more information on the way that the 116x-series calculators and the their first-generation predecessors machines keep track of the registers using magnetostrictive delay line technology, please have a look at the Friden 130 exhibit.

Singer/Friden 1162 Keyboard Detail

The 1162 operates much the same as the EC-132 that preceded it. The keyboard nomenclature differs, but the functionality is very similar. Numbers are always entered into the bottom register (the bottom number on the display) of the stack. The [ENTER] key of the 130/132 is replaced with a key labeled [FIRST NUMBR/CHG SIGN]. This key is a dual function key. The first press completes entry of the number in the bottom register of the stack. A successive press will negate the number. The 130/132 opted for a separate [CHANGE SIGN] key to change the sign of the entered number. The [DUP] key duplicates the number in the bottom register of the stack, and pushes the stack up. The [I] key swaps the content of the bottom two (the registers shown on the display) stack registers. The [TO MEMORY] key stores the content of the bottom of the stack into the memory register (popping the stack) downward (causing the number stored to be removed from the stack), and [FROM MEMORY] recalls the memory register into the bottom of the stack (pushing the stack up). The [CLEAR] key pops the stack, clearing the bottom register, and also serves to reset the "OVERFLOW" indicator. The [CLEAR STACK] key zeroes out all four registers of the stack, leaving the memory register alone.

Another Internal View

Though implemented with integrated circuits, the 1162 isn't dramatically faster than its all-transistor predecessor. The design of the machine was essentially a re-implementation of earlier Friden transistorized design using IC technology. In practice the 1162 is just marginally quicker than the 132. The basic clock frequency of the 116x-series calculators is 2.8MHz, but this fundamental frequency is divided down to 700KHz to make the master clock frequency, over double the clocking speed of the earlier calculators. In spite of this, the 1162 isn't all that much faster than its transistorized bigger brother.

All 9's divided by 1 takes a shade over 1 second, and square root operations can take from around 250 milliseconds to as much as 1.5 seconds, depending on the argument. During calculations, the display is blanked, and the function key is locked down until the operation is complete. Overflows physically lock the keyboard until the overflow condition is cleared with the [CLEAR] or [CLEAR STACK] keys. Division by zero results in the machine looping forever with the display blanked and the keyboard locked, with the only recovery possible (besides power-cycling the machines) being depressing the [CLEAR STACK] key. Extracting the square root of a negative number simply returns an answer as if the argument was positive.

Extremely Rare Item Counter Option on Friden 1162
Image Courtesy of Gerard Timmerman

Gerard Timmerman, a fellow collector who lives in the Netherlands, has come across an extremely unusual Friden 1162. It has a Friden-made item counter accessory built into the calculator. The item counter consistes of a circuit board mounted on the front of the chassis, to the right of the CRT. The board has four TTL IC's, and one DTL IC on it that implement a simple two digit decimal counter. Along with the ICs, there are two small seven-segment LED displays that shine through a red window in a cutout on the front panel of the 1162 to provide a count of the number of entries made into the calculator. When the [CLEAR STACK] key is pressed, the counter is cleared. The counter is incremented when the [FIRST NUMBR/CHG SIGN] key is pressed, or when a math operation key is pressed (excluding square root). The Item Counter is useful for statistical operations, such as performing averages, as well as for invoicing calculations. The item counter appears to be an add-on, not something that could be ordered on a 116x-Series calculator from the factory. I have not been able to find any documentation on the item counter for the 116x-Series calculator, but the fact that Gerard's machine has the option, and the circuit board for the item counter clearly identifies the board as SINGER Part Number 7016765 Rev 1, is a clear indication that this rare item was a real product. It is suspected, though not substantiated by example or documentation, that this add-on was also available on the Friden 1160 and Friden 1166 calculators. Sincere thanks to Gerard Timmerman for providing the photo of this extremely unusual addition to his Friden 1162.

The generation of calculators from Friden that followed the 116x-series (and the printing versions, the 115x-series) were designed and manufactured by Hitachi in Japan, with Singer/Friden logos placed on them. These machines were of a completely different design than the Friden-designed machines, and while the machines had a technically more advanced design (operating on more like a computer than a mechanical calculator, which the Friden designs emulated), the elegance and style of the Friden-designed electronic calculators, the legacy of Robert Ragen, was lost. Fortunately examples of the Ragen-architected calculators exist to this day, and are preserved for posterity.


Text and images Copyright ©1997-2019, Rick Bensene, The Old Calculator Museum.