One of the 1162 Circuit Boards

The 1162 uses small-scale integration IC's for most of its logic. Most of the chips are made by Texas Instruments, with a few Fairchild chips sprinkled in here and there. The machine is made up of a mix of very early 7400-series TTL IC's (mostly 7474 dual flip-flops), along with another line of early TI Small-Scale DTL (Diode-Transistor Logic) chips in the SN158XX series (For example: SN15862[Triple 3-Input NAND], SN15830[Expandable Dual 4-Input NAND], and SN15846[Quad 2-Input NAND]). Along with the compliment of small-scale logic, the 1162 (as well as other machines in the 116x line) use a three chip medium-scale integration device (of unknown logic family) made by Texas Instruments. The chipset consists of SN1286, SN1287, and SN1288 devices. It is my theory that these devices are some kind of arithmetic logic unit chipset that work together to provide the adder that the machine uses as the basis for all of its calculating. If anyone out there has any information on this old TI chipset, please drop me an EMail.

The Singer/Friden 1162 utilizes a total of 93 IC's, along with a significant compliment of transistors, diodes, resistors and capacitors. The main logic of the machine is spread across six circuit boards which are situated vertically in a card cage, plugging into a backplane made from an etched circuit board. The backplane board also contains some power supply circuitry. An additional circuit board mounted near the CRT provides high voltage (e.g.: deflection amplifier) CRT drive functions.

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

Even though IC's had replaced the all-transistor electronics of the earlier 130/132 machines, the 1162 still uses acoustic delay line technology for storing the working registers of the machine. The delay line of the 1162 is contained in an aluminum housing in the bottom of the machine, as in the 130/132, but the whole assembly is definitely smaller than its counterpart in the 130/132.

Inside a Friden 116x-Series Delay Line

Though the 1162 uses small-scale integration IC's for the logic of the machine, the cost of enough IC's to hold all of the bits required to represent all of the working registers of the machine was simply too high to be cost effective back in the late 1960's. For more information on the way that the 1162 and the 130/132 machines keep track of the registers using this acoustic delay line technology, please have a look at the Friden 130 page.

Singer/Friden 1162 Keyboard Detail

The 1162 operates much the same as the 130/132. 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 labelled "FIRST NUMBER CHG SIGN". This key is a dual function key. The first press enters 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" button stores the content of the bottom of the stack into the memory register (popping the stack), and the "FROM MEMORY" recalls the memory register into the bottom of the stack (pushing the stack). The "CLEAR" pops the stack, and also serves to clear the "OVERFLOW" indicator, and the "CLEAR STACK" key zeroes out all four registers of the stack.

Another Internal View

Even though the 1162 is IC-based, it doesn't appear to be much faster than its all-transistor predecessors. It seems that the design of the machine was essentially a re-implementation of earlier Friden transistorized designs using IC technology. The fact that the machine isn't much faster than earlier Friden machines makes sense, as there are aspects of the delay line technology that limit how fast the bits in the delay line can be circulated. Even with faster integrated circuits, the limit of the rate at which bits can be pushed through the delay line would place a limit as to the calculating speed of the machine, regardless of the circuitry used to implement the logic of the calculator.

All 9's divided by 1 takes a shade over 1 second, and square root operations can take from perhaps 1/4 second to 1 1/2 seconds, depending on the argument. During calculations, the display is blanked, and the function key is locked down until the operation is complete. Overflows lock the offending function key down until the overflow condition is cleared with the "CLEAR" or "CLEAR STACK" keys. Division by zero results in the machine locking up, with recovery possible with the "CLEAR" or "CLEAR STACK" keys. Extracting the square root of a negative number simply returns an answer as if the argument was positive.

The 116x-series of calculators included two other machines, the model 1160, which did not provide the square root function; and the 1164, which seems to be a lower-cost version that again skips the square root function, and reduces the capacity to 13 digits. The 116x-series calculators (along with the 115x printing machines based on the same basic design) appear to be the last truly Singer/Friden designs. After these machines were introduced, the following Singer/Friden machines were all designed and manufactured by Hitachi in Japan, with Singer/Friden logos placed on them for sale by the Friden division of Singer. The 1162 and the other machines in the 116x and 115x series calculators are the last of the legacy that started with Robert Ragen's brilliant design for the Friden EC-130.