OPERATING CONTROLS
1 Keyboard 5 Subtraction 9 Tabulator
2 Clear 6 Position Marker 10 Addition
3 Multiplication & Correction 11 Control Display
4 Division 7 Decimal Marker 12 Result Display
8 Return Key
START:
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Press [C] key (2) to clear arithmetic & counter units. Shift the red
slider (6) to the right to clear the input unit.
ENTER A NUMBER:
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The actual number of digits entered are shown with the red slider (6).
If wrong digits are entered, push the slider right to clear the input.
ADDITION:
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Everytime a number is entered and the [+] key (10) is pressed, the
motor starts and the number will be added to the content of the
arithmetic unit (12). THE INPUT IS "BLIND" !!!
REPEAT:
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To enter the same number more than once, press & push to the left
[X] key (3) before pressing the [+] key (10). The keyboard will not
be cleared. To release the [X] key (3): Press & push it right.
SUBTRACTION:
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Enter the number and press [-] key (5) to start the motorized procedure.
NEGATIVE RESULTS are displayed in the arithmetic unit
as the COMPLEMENT of the next higher 10, 100, 1000, ...
Example: -12 = 99...9988
MULTIPLICATION & DIVISION:
--------------------------
Because the counter unit has only O N E decimal, multiplication &
division is tricky, and needs to k e e p t r a c k of numbers
either "IN MIND or ON PAPER" ...
MULTIPLICATION: 123 x 45 = 5535
Press [C] key to clear arithmetic & counter units. Shift the red
slider to the right. Lock the [X] key ...
Enter the multiplicand (=123). The multiplicator (=45) has two digits.
Press & hold the [+] key until the counter will show (with its
BLACK FIGURE) the figure of the multiplicator's "1"-position (=5).
Press the tabulator [ <- ] key. Press & hold the [+] key
until the counter will show (with its BLACK FIGURE) the figure of the
multiplicator's "10"-position (=4). The result (=5535) is in the
arithmetic unit.
DIVISION: 22 : 7 = 3.14285714 Remainder 2
Press [C] key to clear arithmetic & counter units. Shift the red
slider to the right ...
Enter the dividend (=22). Press the tabulator [ <- ] key until the
decimal marker is on its left position. Press the [+] key to transfer
the input into arithmetic unit. Enter the divisor (=07). Press the
tabulator [ <- ] key until the decimal marker is on its left position.
Lock the [X] & [DIV] keys. Press the [ -> ] key to start the motorized
subtraction of the divisor. When the motor stops, the RED FIGURE
shows the 1st digit (=3) of the result. Pressing the [ -> ] key again,
the NEXT DIGIT will be calculated and shown as the RED FIGURE. Continue
until the maximal number of digits are calculated. The remainder (=2)
is shown in the right window of the arithmetic unit.
REMARK: RELEASE THE [DIV] KEY, IF THE DIVISION PROCEDURE DOESN'T STOP
Have a look at "Calculating Trickies" ...
R E M A R K S :
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Two lines of interesting and innovative mechanical calculators came on
the market under the name » CONTEX « in the '50s and '60s :
The first was a key-driven adding machine in style of a Comptometer,
with a "half" keyboard and simplified mechanism: CONTEX-A & CONTEX-B.
The second was a series of 10-Block-Keyboard machines. The CONTEX-10 is
a manual one. This CONTEX-20 is motor-driven. The CONTEX-30 has
improved motor-driven multiplication and division. The CONTEX-55 has
its own DIVISION REGISTER to complete the division full automatically.
impressum:
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© C.HAMANN http://public.BHT-Berlin.de/hamann 03/26/08
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