IM 2007 - international meeting historical calculating instruments

On September 14 an 15, 2007 The international meeting of Collector of Historical Instruments took place in Lelystad / Enkhuizen in the Netherlands. See for more information the website of the dutch circle here .

You can see the text of my presentation here:

Collecting Early Electronic Calculators

A brief history and classification

Early Electronic Calculators – History

• Mechanical calculators
• Electromechanical calculators
• Electronic calculators
• Computers

General

After the era of the mechanical calculators, which lasted till about 1960, the development of electronic calculators started. The mechanical calculators had the limitation that they could only add, subtract, multiply, divide and perhaps one could even calculate the square root. Was it in the beginning just so, that the electronic only was used for the calculating process, in a later stage the electronics was used for the display.

The early electronic calculators are roughly classified in electromechanical calculators, electronic calculators and computers.

The electromechanical calculators are calculators, whereby for the calculation process electronics was used and the results were printed on a printing device.

Through the introduction of the electronics is became possible to calculate soundless.

The electronic calculators characterize themselves by a combination of electronic calculation and electronic display, with or without a printing mechanism.

When the era of the electronic calculators is ending and when the era of computers is beginning is harder to indicate. If it is considered that the limitation the use of text, use of internal memory, than we can see that these machines were already there in the 70s.

The development was aimed to make the calculators still faster, smaller and give them a lower energy consumption. As an example of the development in time you find a picture of a one digit display board for the Anita calculator from 1963 next to a pocket calculator from 1973.

Probably only 50 different cathode ray display calculators were made, a few hundred nixie tube machines and about 4000 different types of LED / VFD pocket calculators.

As first electronic calculators are considered the ANITA and the Friden 130, which came on the market in 1963. The Anita had a nixie tube display and the Friden had a cathode ray display ( a kind of TV display ).

In 1997 there was made an attempt by Guy Ball and Bruce Flamm to classify the LED and VFD pocket calculators in a catalogue. This book contains 1500 different calculators. Meanwhile there are several collectors who have already twice this number. The catalogue is still fairly available on internet, and is regularly offered on Ebay.

Collecting early electronic calculators is a hobby that in general is very affordable and when it is restricted to pocket calculators it also takes little space. In comparison with collecting stamps or coins, where everything is already known, is collecting calculators an undeveloped field, where always you can discover new things.

An important reason to collect this kind of early electronics is that you can see an enormous development in technique during a very short period ( 1963 – 1980 ). Also there are a huge number of different designs.

Early electronic calculators – classification

• Brand & type number
• Size
• Application possibilities
• Calculation logic
• Display type
• Keyboard type
• Power Source

Collecting of calculators can be made on above classifications. Besides this collecting can also be made on country of origin, with or without printing mechanism, etc.

Early Electronic Calculators – Brand & Typenumber

• major brands
• Factories
• Countries

The development of calculators looks a lot like the development of the car-industry. In the beginning a lot of coachbuilders made cars, and there was an enormous diversity of brands and models; after that caused by price reductions it became necessary to improve the efficiency and remained only a few producers.
This evolution can also be seen with the calculators. At first all producers on the field of electronics, office machines, photography etc made calculators. The prices were high and the performance was bad. At the end of the 70s the fall of the prices began and a lot of brands disappeared like snow before the sun. In the end only a handful of brands remained.

During the period 1963 – 1980 there were around 600 different brands of calculators, of which a lot of brands only produced one type. These brands came from around 150 different factories.

Among the calculator brands are also brands that were issued by chain stores. In Germany for example the calculators of the chain Quelle were sold under the name of Privileg, In the Netherlands the Texas Instruments calculators were sold under the brand name Reactor, internationally the brand Prinztronic was sold at Dixons.

In the beginning the calculators were mainly produced in the USA and Japan – in Holland the name of the pocket calculators was “zakjapanner” pocket Japanese - , shortly the production was transferred to Hong Kong and Taiwan. Besides that calculators were also produced in many other countries, like Mexico, Indonesia Argentina.

Early electronic calculators – Size

• Desktop calculators
• Pocket calculators

An important classification for collectors is the classification in desktop calculators and pocket calculators. Collecting desktop calculators is less collected because the use a lot of space. These desktop calculators therefore are easier to get, however is the number of brands and types restricted as they were mainly produced for office use. Pocket calculators were intended for consumers en formed a bigger market and therefore have a wide variety.

Early electronic calculators – application possibilities

• Adding calculators
• Basic calculators
• Scientific calculators
• Programmable calculators
• Financial calculators
• Graphic calculators
• Special calculators

Adding calculators
Although I don’t know any electronic adding machines, there should have been some in any form. Counting mechanisms shall be found in measuring equipment, clocks or similar.

Basic calculators
Of all calculators the basic calculators are produced the most. The functions of these calculators are: add, subtract, multiply and division. Besides that some calculators had the possibility of a memory, and sometimes the square root.

Scientific calculators
Scientific calculators characterize themselves because besides the basic functions also the geometrical and algebraic functions were added.

Programmable calculators
To the programmable calculators is added the extra functionality to make it possible to execute several steps one after another.

Graphic calculators
The graphic calculators are scientific calculators which also include graphical applications. They were made since the 90s. At internet they are sometimes offered as geographic calculators – perhaps by students who did not pass the exams.

Special calculators
It is impracticable to mention all special calculators. Slide rules were made for very special purposes, like for example the aviation; electronic calculators were made as standard.
The calculator factories have tried to put all kind of calculations in the machine ( sometimes with the application of reading programs by means of magnetic cards ).
For sure there came an enormous diversity in design and combination with other products.

Below you find a brief survey :

Watch calculators
Navigation calculators
Pen calculators
Lighter calculators
Feminine calculators
Eurocalculators
Calculators with a radio
Calculators with a voice recorder
Projection calculators
Banknote – shaped calculators
Calculators for chemical calculation
Astro calculators

Early Electronic Calculators – Calculation logic

• RPN and normal calculation
• 80 different logic possibilities

RPN
The abbreviation RPN stands for Reverse Polish Notation, and is an in 1920 developed method to note a mathematical expression without round or square brackets.
Because the operation command has to be given first and at a later stadium the number, keystrokes are limited and sub calculations can be viewed, which results in correcting errors in a better way. RPN is especially used by Hewlett Packard in their calculators.

80 different logic possibilities
Besides the RPN method there are several other possibilities for calculation logic. Gerhard Wenzel has made a classification tree for the basic calculators, in which he discovered 80 different possibilities of calculation logic. Starting point are the calculations: 2 + 3 + =, 2 + 3 / =, 2 * 3 + =, 2 + 3 = 2 etc. It is very peculiar to see that the calculators made give so much different results.

Early Electronic Calculators – display type

• Cathode ray tube
• Vacuum tube
• LED
• VFD
• LCD
• Other displays

Cathode ray tube calculators
Of this kind of calculators with a display like a small TV screen there are just a few different models. The best known are the Friden 130 and the 132. Remarkable detail of these calculators is that the overflow is mechanically protected. For example, if a division by zero is initiated, the complete keyboard is blocked. By pressing a special key, the mechanical blockade is removed.

Vacuum tube
In this category belong the nixie tube and other kind of tubes. The difference between the display of these two kind of display is that the nixie machines light up every digit fully ( the numbers are one after another in the tube ), where the other vacuum tubes light up the numbers by lighting segments of the display.

LED
The abbreviation LED means light emitting diode. This kind of display was used mainly by the pocket calculators of the starting period. In general it gives a red display.

VFD
This kind of display ( Vacuum Fluorescent Display ) in general is coloured green. These kinds of displays were introduced after the LED, and had lower power consumption.

LCD
This Liquid Crystal Display came in the late 70s en is still produced. IN the beginning they were coloured yellow to protect them against the UV-radiation. By improving the display this was not necessary afterwards.

Early Electronic Calculators – keyboard types

• Telephone keyboard vs calculator keyboard
• Relation with computer logic

Telephone keyboard versus calculator keyboard
The telephone keyboard has the keys 1 2 3 at the upper row and the calculator has them on the lower row. A lot has been written on the difference, but is a fact that the keyboards of the calculators started first ( the telephone in former times used a round dial ). The keys of a calculator 1 2 3 are at the lower position, because these numbers are used more frequently.
The logic of the keyboard grouping is hereby proved. For the telephone keyboard this is more difficult. There is a story that this is initiated because the 1 on the dial is at the top. Another story says that it is originated to make the difference between the office machines ( a telephone is not a calculator )

Relation with computer logic
Besides the number grouping you can classify the keyboards also in another way. For the RPN-originated input there is a big ENTER-key, with which the data are put in the memory. The minimum of keys of the calculator ( if they are not supplied with a decimal pointer key) is 15, 10 for the numbers, 4 for the calculations and 1 for the correction. The maximum number of keys found on a scientific pocket calculator is 49, on a Commodore SR9190R.
In general the scientific and algebraic functions are placed above the number part, and the basic functions on the right of the number part.

It is utmost worth mentioning that the ANITA, one of the first electronic calculators, still had a keyboard of 10 rows of 9 digits, fully based on the old counting machines.

Early Electronic calculators – Power Source

• Electricity
• Batteries
• Solar Powered

The categorisation of calculators by power source will not be a collecting method, but is an additional data. Other data which may be of interest to characterize calculators are for example length, width ad thickness, and weight.
In the beginning calculators were real energy consumers. There where always a 9 Volt battery was needed, it is now so that the LCD calculators now function with a consumption of 0.0001 Watt. Nowadays there are even calculators the function on water.

Besides this general description of collecting I would like to put forward some electronic calculators, which are remarkable in a special way.

ANITA MK series
The Anita MK series were the first calculators. This Anita was the first calculator to work noiseless, and was available for a reasonable amount.
They had 10 rows of 9 keys ( for the numbers 1 to 9), and at the side of it 9 keys for multiplication. Below each row it had also a key for the decimal pointer. For each of the basic operations ( add, subtract, multiply and division) it also had a key.

Monroe 10
This calculator stands in between of a pocket calculator and a printing calculator. The data were printed on a strip. These calculators from the early 70s were sold in limited numbers because of the high prices of the cartridges.

Sinclair
The British electronic manufacturer Sinclair was famous because of his unique and innovative designs. A very good example is the Sinclair Sovereign from 1976, which regarding its design, could match in this century.

Faber Castell TR series
During the fast development of the pocket calculators Faber Castell also tried to attend the market with a combination of a pocket calculator and a slide rule. Although the calculator has a remarkable design, these calculators were sold in a limited number. The TR1 and the TR3 were in a red LED version, the TR2 and the TRX ( already without a slide rule) had a green VFD display.

Hewlett Packard HP01
The combination of a calculator and a watch is united in this specimen. Produced in 1978, and was for sale in the Netherlands for Hfl. 2.250.-- with the slogan “he also knows what time it is”.

Olympia CD 80
A very beautiful example of design from the 70s is this Olympia CD80, which by the shape of the keyboard, display and keys really shows that it comes from the space age.

It only remains for me to say that for my collection I have a website, where you can read the things mentioned. I hereby refer to www.calculatormuseum.nl