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Canon Canola L163 Calculator

Updated 2/21/2000

This calculator is a very good example of the way that the stunning speed of advances in Large Scale integrated circuits shrunk down the size and weight of electronic calculators. The Canon Canola L163 is essentially a redesign of the earlier Canon 163 (and its Monroe companion, the Monroe 990) using updated technology. To elucidate the differences the technology made in the short time between the 163 and the L163, compare the two machines in the table below.

MachineCanon 163Canon L163
Introductionmid-1968early-1971
Weight17 Pounds8.6 Pounds
Volume575 Cu. In.330 Cu. In.
IC's170 SSI6 LSI, 1 SSI
Circuit Boards82
Power Consumption17 Watts16 Watts

The two machines function virtually the same, with only minor changes between them. The L163 gets the benefit of a few additional features as a result of its newer technology, among them, leading zero suppression, a simple-minded percent function, an electro-mechanical item counter, floating decimal point operation, and more fixed decimal point position selections. From a technology point of view, the earlier Canon 163 used small-scale integrated circuits, with 170 IC's scattered across eight rather large plug-in circuit boards. The L163, in contrast, puts all of the circuitry of the machine on two circuit boards, the largest of which is about the same size as one of the circuit boards in the earlier 163. The L163 has a total of seven integrated circuits, with the majority of the function of the machine contained on a four-chip calculator chipset. Essentially, each LSI chip in the L163 chipset replaces over 30 of the earlier small-scale intergrated circuits. This comparison doesn't account for the fact that the earlier Canon 163/Monroe 990 had to use an acoustic delay line for storing their working registers, while the L163 has circuits within the LSI chipset for storing all of the registers of the calculator. It is clear to see that literally within the period of perhaps 24 months between the design of the Canon 163 and the Canon L163, integrated circuit technology had come a very long way.

Interior of Canon L163

The Canon L163 was clearly designed as a 'high-end' office calculator. The machine has a 16-digit Nixie tube display, with 'comma' indicators situated above the display digits to help make it easier to read large numbers. The L163 can operate in fixed or full-floating decimal modes, with fixed decimal point locations at 0 through 8, 10, 11, or 12 digits behind the decimal. The decimal point mode is selected via a rotary switch on the keyboard panel. The machine, like its less-feature-laden, but similar vintage design Canon L121, has a built-in carrying handle that extends out the back of the machine for easy transport of the calculator.

Canon also produced a model L162, identical to the L163, but omitting the square root function. The two machines are identical, the only difference is that the square root key is omitted from the keyboard assembly on the L162. The cost difference? $100! Amazing how much it cost the end user for the square root function when the real difference between the machines was an additional keyswitch, a slightly different keyboard panel, and a different model tag.

Some of the LSI's in the Canon Canola L163

The Canon L163 is an early LSI IC-based calculator. This particular machine was built in the mid-1971 timeframe, based on date codes on parts in the machine. This example of the L163 seems to be a very early production unit, with a serial number of 200179. The serial numbering appears to begin at 200001, so this is only the 179'th of this model machine made. As mentioned before, the L163's calculating brains come from a four-chip LSI chipset, made by Texas Instruments. The chipset has TI part numbers TMC1761, TMC1763, TMC1764, and TMC1765. The chipset is supported by two ROM (Read-Only Memory) IC's (TI part numbers TMC1767 and TMC1768), leading me to believe that the chipset is actually a microcoded calculator engine, with ROM firmware determining the functionality of the machine. All of the main logic of the machine is packed onto one circuit board that occupies the bottom of the case of the machine. This circuit board plugs into an edge connector, which, though hand-wired interconnects, hooks the 'brains' into the power supply and the display subsystem. The Nixie tube display is driven with discrete transistor driver circuitry, and is multiplexed. The display (as opposed to the earlier 163) provides leading zero suppression. The L163's keyboard is of conventional magnetic reed switch design. The keyboard plugs into the main board with an edge connector. The power supply is a linear, transistor-regulated affair, occupying the back section of the calculator, behind the display tubes.

Canon L163 Keyboard Detail

The Canola L163 performs the standard four functions along with square root. A push-on/push-off keyboard switch labeled "K" enables or disables the constant function, which operates in multiplication and division only. The "%" key simply shifts the decimal point two positions to the left, effectively dividing the current number in the display by 100. The "RV" key swaps the two operands in multiplication and division operations, useful in cases where the divisor and dividend in a math operation need to be swapped. The 'back arrow' key deletes the last digit on the display, shifting the display to the right. This 'digit at a time' form of input correction is a thoughtful feature included on most Canon calculators. The 'back arrow' key on the L163 properly handles backspacing over an entered decimal point, as opposed to the decimal point 'wrapping around' if backspaced over on the Canon Canola L121. If the user catches an entry error late in the entry of the number, where backspacing would be too tedious, the "CI" (Clear Indicator) key clears the display to "0". The "C" key clears everything except for the memory registers, which each have their own individual clearing function keys. The L163 has two memory registers. Each register has a neon indicator in the keyboard panel which lights to indicate that the register has non-zero content. One register, with control keys on the right hand side of the keyboard, is memory register 2. This register can be used as an manual accumulator, or as an automatic accumulator that adds the first number in multiply or divide operations to the memory register. A slide switch situated above the memory control keys selects the operational mode of memory register 2. The other memory register, obviously called memory register 1, can operate only as an accumuator, which, when the push-on/push-off "AM1" key is depressed, automatically accumulates the results of addition, subtraction, multiplication, or division. Each memory register has its own independent clear key ("CM1" and "CM2"), and a key to recall the content of the memory register to the display "RM1" and "RM2"). A slide switch selects whether or not the calculator performs truncation, round-off, or round-up. A neon tube indicator at the left end of the display, with a cut-out window showing an arrow shape pointing to the left indicates any overflow condition, and a similar indicator, at the right end of the display, with a window in the shape of a minus sign, indicates if the number in the display is negative. Dividing by zero results an immediate overflow condition, with the display cleared to "0" and keyboard entry (other then the "C") key locked out. Pressing the "C" key clears the overflow condition.

The electro-mechanical Item Counter

An interesting and rather unique feature of the Canola L163 is the item counter. Situated on the left upper part of the keyboard panel is a small window that shows the content of a two-digit electro-mechanical counter. Slightly above and to the left of the counter window is a pushbutton that clears the counter to "00". This counter is connected to the "+=" and "-=" keys such that it increments on each depression of either key. This effectively 'counts' the number of addition or subtraction (accumulation) operations performed by the machine, useful for operations such as calculating averages. The counter is activated by a small solenoid.

Canon/Monroe Jumpers

An interesting discovery was made while poking around the insides of the L163. Two jumper wires apparently change the 'personality' of the electronics. The jumper wires can be installed in the circuit board in either of two positions. One position, the way they are installed in this machine, is labeled "L 163/162", and the other position is labeled "M 650" (For Monroe 650). It is well known that Canon produced calculators for Monroe. Monroe was (and still is, surprisingly enough!) a US-based calculator company that excelled in mechanical calculators, but was caught off-guard by the advent of electronic calculators. Rather than try to 'grow their own' electronic calculator expertise, Monroe partnered with high-end calculator design company Computer Design Corporation for high-end (scientific, special-function, and programmable) machines, and Canon for more general function office calculators. The "M 650" position for the jumpers causes subtle differences in the function of the machine, making it possible to use the same circuit boards in the Monroe version of the machine.

Canon L163 Display Subsystem

The L163 is relatively fast, and definitely faster than its earlier- technology equivalent. The square root operation takes the longest to perform, with difficult square roots returning an answer in just under two seconds. During the time the calculator is busy calculating, the display is blanked, however, the 'comma' indicators flicker around, and the "-" indicator comes on, apparently acting as a 'busy' indicator. Once the calculation completes, the "-" indicator goes out (unless, of course, the result is negative), and the comma indicators settle to their proper locations. The "all nines" divided by one benchmark takes about 1/2 second to perform. Most all other operations consume only small fractions of a second to complete. Taking the square root of a negative number does not cause an error condition, the negative sign of the operand is simple ignored.

A Profile View of the L163

This particular machine was purchased brand new in the Portland, OR area. A tag on the back indicates that it was purchased at "Oregon Typewriter and Recorder", a well-known office machine supplier located in the downtown section of Portland, Oregon. Given the date of the parts inside the machine, my guess is that it was purchased new sometime in late 1971. The machine is in nice condition, requiring only a minor cleaning of the cabinet and keyboard, and blowing out of some dust on the inside. It operates flawlessly, and I'm sure it served its original owner very well for many years. Sadly, many old calculators, even though they still work fine, are replaced with newer, smaller, lighter, and easier to use technology over time. This machine was apparently taken out of service and given to a local thrift store. Fortunately, it was found there by a fellow collector and rescued from an uncertain fate, and later made its way into the Old Calculator Museum.


Text and images Copyright ©1997-2011, Rick Bensene.