CANON CANOLA L100A – Planar display calculator

In the early 1970s, the Japanese company CANON mainly produced professional office calculators. Their quality was really high, after all, at that time the Japanese specialized primarily in industrial equipment, whose workmanship is by definition better compared to consumer devices. 

However, the company had to respond to the ever-growing market for home appliances and introduce something for the ordinary user as well. The plan was quite ambitious – to design equipment that would be characterized by industrial quality and low price at the same time. The result of the Japanese engineers’ work was the launch of two home calculators, designated L100 and L100A, in 1971. In this material we will take a closer look at the L100A, the L100’s successor, which was released very soon.

CANON L100A, in its full glory

In designing the L100A calculator, CANON opted for a classic, already proven body. The device is composed of two parts – the upper one in yellow/cream color and the lower one dark falling slightly into brown. Interestingly, the entire housing is finished with a texture intended to resemble a bit of leather. The keys are made of smooth plastic, of which the markings are an integral part, so there is no possibility of abrasion. Above the keyboard, behind the dark translucent plastic, the display is placed. The rest of the calculator contains only the marking and vents. 

From the outside the calculator indeed seems very solid, it is worth noting that it is also quite heavy, weighing more than 1.2kg. The element that betrays the consumer purpose of this equipment is the keyboard, and it’s not about the keyboard itself, because you can’t complain about that, the stroke of the keys is quite large, but they are precise. Looking at the keyboard, you can immediately tell that the L100A is a very simple design. Only four basic actions are supported here, which would be unthinkable in office equipment. In addition, the CANON uses algebraic instead of arithmetic mathematics for calculations, has no memory and does not support rounding.

Logo and model designation

On the front of the device, under the hole intended to dissipate heat, there is a logo and model designation, the Canon Canola L100A. It might seem that this component is made of metal, but it is a plastic that imitates brushed aluminum in texture.

Nameplate

On the underside of the calculator we find nothing of interest except the nameplate and a puzzling circular sticker with the number 05. On the nameplate we found the manufacturer’s logo, model designation, power supply information, serial number and a small pictogram informing us that the device complies with protection class I, that is, it has a grounding.

Mysterious orange display

One of the things that sets CANON’s calculator apart from other 1970s designs is the display. When you turn the device on, you may notice that the digits on the display are quite strange. They are orange in color, which is quite unheard of, usually in calculators of those years VFDs were mounted glowing in green/non-blue color here, however, we have something that looks a bit like a Nixie lamp. In reality, however, it is a so-called planar display, but I will say more about it later in the article. 

Let's take a look inside

Calculator after opening the case

It’s time to look inside the device, for this we need to remove the four screws located in the front of the lower case and on the back. After removing them, the calculator can be disassembled into two parts. 

At first glance, you can see that it is quite rich and professional here. In the upper part of the case there is an integrated keyboard and a display cover. Interestingly, around the semi-transparent plastic there was a metal grounded sheet with an additionally applied sponge to protect the structure of the display itself. The second part of the case housed the motherboard, abundant with components, the display and the power supply.

Keypad based on reed switches

Let’s take a closer look at the design of the keyboard, as it is very interesting. Its operation is based on glass tubes with metal plates inside, or in a word, reed switches. Each key has a magnet, which, when pressed, approaches the glass tube, and the magnetic field causes the metal plates to connect and close the circuit. 

Under the keyboard, you can notice one more element that confirms the higher quality of the calculator. These are the threads into which the screws were screwed. They are not plastic as in most calculators of those years, but metal, glued into the case. An identical solution can now be found in laptops. Very often the hinges connecting the matrix with the rest of the structure are mounted precisely on the glued-in threads.

Motherboard

Looking at the motherboard of the L100A, one can see the multitude of components. The calculator actually has two processors, these are physically the two largest chips – TMC1824 and TMC1825 made by Texas Instruments. The other chips, the dual KH6248 and KH6249 handle the display, while the smallest KH5305 generates all the clock signals needed for operation. In addition to this, the calculator board included several transistors and other passive components, such as resistors and capacitors. 

Planar display

By far the most interesting and mysterious part of the L100A is its display. It is not the usual LED, VFD tube, or Nixie bubble. It most closely resembles a Burroughs Panaplex display, except that some studies say that it is precisely this type of display, but this is not true. In fact, this display was developed earlier than the design from Burroughs and is referred to as a planar screen. To put it another way, this display is based on Nixie technology and is described in some sources as the world’s first plasma screen. In my opinion, such a thesis is a bit exaggerated, but one can indeed see some analogies in the planar and plasma display. 

Like the Nixie tubes, the display of the L100A calculator is filled with neon, which can glow when a sufficiently high voltage is applied. Here, however, the gas is not common to all characters, each digit is like a separate lamp. In each bulb are placed tin plates that together form a single seven-segment sign, when we apply voltage to specific segments we can make the neon gathered around them glow. But where did the comparison to a plasma display come from? It could be the fact that each segment somewhat resembles a single chamber filled with glowing gas typical of plasma screens.

Although we see only 11 digits, the display actually has 12, with one of them hidden under a black sponge on the left side. This is a treatment as planned, since the integrated circuits used in the calculator were adapted for multiplexing 11-digit screens. During operation of the device, the segments of the extra character can blink in a random manner. Another interesting feature is that the display is turned off when the calculator is performing calculations. 

Power section

The last element to be described is the power supply. Its design is simple, linear transistor regulated. By far the largest component here is the transformer that generates all the necessary voltages. On the left side you can also see the device’s on/off switch. 

Planar display in action

CANON Canola L100A is a very interesting and unique design, especially by the display used here. It also has to be said that the build quality stands at a really high level. The only element that the calculator does not cope with is the speed of operation. The device is quite slow and deviates here from the designs of other manufacturers, for example, filling the display with nines alone and dividing them by one, we get the result after about 1/4 second which is quite a poor result. 

Sources:

  • http://www.calcuseum.com/SCRAPBOOK/BRAND/BURROUGHS_parts%28E%29/1.htm
  • https://www.oldcalculatormuseum.com/canonl100a.html
  • http://www.datamath.org/Related/Canon/L100A.htm
  • http://www.datamath.org/Related/Canon/L100.htm
  • http://www.calcuseum.com/SCRAPBOOK/BONUS/10577/1.htm
  • https://www.industrialalchemy.org/storearticleview.php?item=111

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