Canon Palmtronic 10M (LD-10M3)

Palmtronic 10M (LD-10M3)
Palmtronic 10M (LD-10M3)

In the 1070ies, Canon offered many pocket calculators with the name "Palmtronic" for office usage. At first, they had LED displays, then green VFDs and finally LC displays.

From the bloom of that era originates the Palmtronic 10M, whose exact name is LD-10M3, which was made in 1976. It was got a green VFD with 10 + 1 digits and is capable of the standard calculations plus a handful of special functions for business and finance usage.

This calculator belongs to the top class because of the design and the quality and even 30 years later, it is a pleasure to work with.

back side with battery compartment
back side with battery compartment

Case and Keyboard

Not many calculators of the seventies were made in such a perfect way, as the Canon Palmtronic 10M. There is nothing, that slantes, nothing that squeezes, nothing that sounds hollow, nothing, that feels cheap, including the battery cover. And on top, it even has got a very nice aluminium cover plate.

The darkened glass in front of the display fits perfect and is surrounded by a silver-tone border.

The keyboard with its perfect pressure point and always perfect contact belongs to the best one ever made and I would say, it even tops the keyboards from HP and Casio calculators. Of course, the switches all give perfect contact, too.

The keyboard is divided into two portions: The lower, larger keys are used for the standard calculations (including the double-zero and digit-wise delete keys), while the smaller keys on the top can be used for the less common functions, such as percentage and power calculations.

switch on the front side
switch on the front side

With the four-stage switch on the front, you can set the treatment of the decimal places.


Inside view
Inside view

The inner space of the Paltronic 10M is used by a large PCB, which covers almost 3/4 of the space. The lagest space consumer is the CPU with 40 pins. Except this part, there is not much discrete electronics inside, only two transistors, four electrolyte condensers, a high voltage transformer and a handfull of diodes, condensers and resistors. Here you see the technical advancec, because only a few months before, it would have been twice the amount or more.

details of the mainboard, including CPU
details of the mainboard, including CPU

The keyboard is connected with 24 wires on the side. Since 28 keys plus one switch is used, there can be neither a 1:1 connection, nor a matrix. How the keys are really organized, I don't know.

Additionally, on the writings on the PCB, you can very well see the multiplexing connection of the VFD.


The Canon Palmtronic 10M uses a very modern flat VFD, a NEC LD 8152. This display lights brightly cyan, has got rather small digits with a height of 4.5mm and contains 11 digits. Ten of them are used for displaying the numbers; the eleventh and leftmost digit indicates memory usage (with a "'" sign), negative numbers and errors ("E").

During the power calculations, the exponent modulo 10 is counted down here.

The VFD of the 10M has got an additional feature, which is hardly seen anywhere else: The thousand, million and billion numbers are separated with delimiter sign (here: "'"). This presenation is quite normal in the USA. On the 10M, for example a million is shown as "1'000'000.".



The CPU is a Texas Instruments TMC 1277NL with fourty pins, which was made in week 40, 1976.

Calculating Capabilities

The LD-10M3 uses, as many other calculators, a simple entry logic, where the terms are executed just the way, they were keyed in. Besided the four standard calculations, it also offers two variants of percentage calculation, the stardard percentage calculation and percentual deviation.

On the standard percentage calculation (e.g. 1.99 + 10%), you key in "1.99 x 10% +" to get the correct result (here: 2.189). This is the standard way on almost all calculators.
If you want to substract, you have to use the minus key instead.

On the percentual deviation, you have to multiply both values and then press the percent-delta key. Example: "3 * 1 Δ%" results in "-66.66666666". Here the last digit is wrong, because if you round correctly, it must be a seven instead of a six.

The memory functions offer the standard accumulation handling with the familiar "M+=" and "M-=" keys. The key "RM/CM" first displays the value stored in memory, and when pressed the second time, clears the memory.
The function of the "MU&MD" key is unknown to me.

memory indication
memory indication

A little curiosity can be found with the "a^n" key, which calculates integer positive powers up tu 99: Interally, this is the same, as repeating the multiplication of a n times, which can take very long (1.001 ^ 99 takes 16 seconds!). During that time, the display is cleared, except the indicator digit on the leftmost place, which counts down the powers modulo 10 and gives the user a visual feedback, that the calculator is busy.

The key "RV" gives back the last value before an operation.

Interally, it calculates with max. 9 digits after the decimal point. If there are fewer digits available on the display, then it calculates internally with fewer digits, too.

A division by zero is correctly handled with an error; an overflow also leads to an error indication, but the calculations can be continued by pressing the "CI" key. The value, which is shown in the display then, has to be corrected by a factor of 10^10 manually.

Error or overflow
Error or overflow

The Palmtronic 10M has got two switches, a constants switch on the keyboard and a switch on the front, which sets the treatment of the digits after the decimal point.

The constants switch works only on multiplications and divisions. On every keypress of "=", the first value is multiplied or divided with the former result.

The decimal place switch has got the familiar positions "2" (two fixed decimal places), "0" (no decimal places) and "F" (float number) and a fourth position denoted "+", which is unknown to me.


The Canon Palmtronic 10M in its third version (also known as LD-10M3) is certainly a very collectible pocket calculator, not only because of its excellent manufacturing, but also because of its unusual display and quite scary power calculations.

calculator with original leather case
calculator with original leather case

Technical data

ModelPalmtronic 10M (LD-10M3)
Display10+1 digit VFD
Number of keys 28
Functions+ - * / % M a^n Mu&MD
Entry logic (classificationALG (BDA (BBAAA))
1 + 0.000 = 1.
0 / 0 = Error
Power supply 2xAA
Power consumption 0.4 W
Size14,3 x 7,4 x 2,2
Serial Number555229

Datamath Calculator Museum: Canon Palmtronic LD-10M 3 a.k.a. Palmtronic 10M (en)