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Jan van de Veen, Nijkerk, The Netherlands




Some mechanical calculaters that are in the museum too

MonroeMatic.JPG (39500 bytes) MonroeMatic

This is an electric driven mechanical calculator made by Monroe. It still works. It was mainly used to carry out simple statistical analyses. You could quite easily make sum of squares and total sum of squares that are needed when doing Analyses of Variance. For more complex analyses the Institute used time-sharing of Honeywell-Bull on a 300 baud tele-type !.
This machine was made in Amsterdam, as Monroe had an office and factory there for the European market. I did never work with this type of calculators, but I know how to make it move and have it  make a lot of noise.

Friden.JPG (44101 bytes)  

Friden SBT

This is a calculator from another famous company, called Friden. To know about the history of Friden click here.
You could perform correlation and regression analyses on this machine.
In order to do so you need sum of square X, sum of square Y and sum X * Y. To get this result, you would enter X and Y as one number, with sufficient zero's in between. If   X = 35 and Y = 48,  you would enter 3500048 and have this number squared. The result will be 12250336002304. The left four digits are 35*35, the last four digits 48*48 and in between is 3360, which is 2*(35*48). Add this result to the total sum, and progress with the next entry. Extreme care had to be taken to avoid overflow, and that is why the carriage has so many digits. By 1977 these machines  where replaced by electronic calculators.

Friden1151.JPG (12898 bytes) Friden 1151

This electronic calculator was bought by the Institute in 1969. It had a paper writer and 4 numbers could be stored in memory. It was even possible to make a small program of 15 steps at a maximum. Today we would call it a macro as the machine ' learned' what to do, because you performed the calculation with the 1151 set to learn mode. You would than enter the starting values and had the program running.
I cannot recall what we did with this wonderful machine, but I will never forget how to find the square root of a number by using the Newton algorithm.


Fridenkeyboard.JPG (38489 bytes) This image shows the simple keyboard of the Friden 1151. The learn button is at the right, just next to the wheel where you could set the number of decimals to be printed.
How do you find the square root of a number ?
Suppose you want to know the square root of 285.
You know that it is more than 10, but less than 20, so make a guess in between, say 15. Now, you divide 285 by 15 with 19 as result. Take the mean of (15+19) = 17 and start again, dividing 285 by 17 with 16.75 as result. Take the mean of (17+16.75) = 16.87. Again divide 285 by 16.87 with 16.89 as a result.
It is now clear to see that 16.88 is the square of 285 and that we found this result in an iterative way, using only 3 cycles. When the Friden had learned this trick, you would enter the number you want the square root off, than enter your guess, and hit the auto button. The result would be printed and the program had to be stopped manually as soon as there was no more change in decimals in the printout.
friden130.JPG (18108 bytes) This is a Friden 130 from 1963.
It was the first all electronic calculator with a 4 line CRT display. Although never used on the Institute, I did add this calculator because it has delay lines as memory.
Please visit the site Vintage Calculator Web to learn more about this calculator.

(Courtesy Mr Horsman)

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@2019   Nijkerk,  The Netherlands