TECHNICAL DATA of the Mechanical Calculator O D H N E R » Model 27 «
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Serial Number: 27-174940
Dimensions: (ca.) Width = 12 " / 30 cm
Depth = 6 " / 15 cm
Height = 4_1/2 " / 12 cm
Weight: (ca.) 11_2/3 lbs / 5.3 kg
Mechanics: Pin-Wheel / Sprossenrad
10s Carry Mechanism
Counter Stepping Mechanism + Animation
Functions: Add, Subtract, Multiply, Divide
Back-Transfer / Rueckuebertragung
Registers: Input = 10 Decimals
Counter = 8 Decimals
(NO Carry; Neg.Figures RED)
Arithmetic = 13 Decimals
Manufacturer:
ORIGINAL-ODHNER
Goeteborg / Sweden
1935
H O W T O U S E the ODHNER Model 27
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BASIC SETTINGS:
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(a) Crank:
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For addition (+) the crank is turned clockwise; for subtraction (-) the
crank is turned counter-clockwise. In idle position the crank is down &
locked. To make one or more turns with the crank, pull out the handle
to unlock. When finished the turn(s), let the handle snap into the lock
again. The locked down position only makes other functions accessible.
REMARK: Every started turn has to be finished completely!
Accidentally started turns are correctible somehow.
(b) Clearing Registers:
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Procedure to clear the input:
Pressing the BUTTON on the right side (with the thumb) will close
the lower ends of the "input-slots". Turn the crank clockwise until
all input-levers are reset because of this new barrier in the "input-
slots". Than turn the crank COUNTER-CLOCKWISE (!) until the BUTTON
POPS BACK and re-opens the barrier of the "input-slots".
The counter unit
will be cleared with the CRANK on the LEFT SIDE of the carriage
The arithmetic register
will be cleared with the CRANK on the RIGHT SIDE of the carriage
(c) Shifting the Carriage:
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Pressing down the LEFT or RIGHT BUTTON IN FRONT will move the carriage
one step left or one step right. When the SILVER KEY is pressed, the
carriage can be moved continuously right or left by hand.
The left position "1" is the "Start Position" of the carriage.
(d) Back Transfer:
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For continuous multiplication the contents of the arithmetic unit
can be back transfered into the input register with this procedure:
o Clear input register as described above.
o Pull the BLACK KEY right on the arithmetic unit.
o Make a "CLEAR" (clockwise) turn for the arithmetic unit.
This clears the arithmetic unit ...
and set the input levers to the transfer-value.
The BACK-TRANSFER-Procedure works in position 1 of the carriage only..
If the BACK-TRANSFER-Lever is set accidentally, push the little
button under it to release the BACK-TRANSFER-Lever.
ADDITION & SUBTRACTION:
=======================
Example: 123 + 45 - 6 = 162
Clear input, counter and arithmetic units.
ADD: Enter the first number (123) in the far right of the input unit.
Make a positive (clockwise) turn with the crank to transfer the number
into arithmetic unit. The counting unit displays the figure 1. Enter the
second number (45). Make a positive (clockwise) turn with the crank to
add the number. The arithmetic unit displays the intermediate sum (168)
and the counting unit displays the figure 2.
SUBTRACT: Enter the third number (6). Make a negative (counter-clockwise)
turn with the crank. The arithmetic unit displays the result (162) and
the counting unit is decreased by 1.
REMARK: NEGATIVE RESULTS are displayed in the arithmetic unit
as the COMPLEMENT of the next higher 10, 100, 1000, ...
Example: -12 = 99...9988
MULTIPLICATION:
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Example: 123 x 45 = 5535
Clear input, counter and arithmetic units.
Enter the multiplicand (123) in the far right of the input unit. The
multiplicator (45) has two digits, so the carriage is shifted to
position 2. Make positive (clockwise) turns with the crank, until the
first figure of the multiplicator (4) will appear in the 2nd position of
the counter unit. Shift the carriage to position 1. Repeat making positive
turns with the crank, until the second figure of the multiplicator (5)
appears in the 1st position of the counter unit. The multiplication is
done: The multiplicand (123) stays in the input unit, the multiplicator
(45) in the counter and the result (5535) is in the arithmetic unit.
DIVISION:
=========
Example: 22 : 7 = 3.1428571 Remainder 3
Division requires 3 steps:
(1st) To Set the Dividend into Arithmetic Unit:
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For the maximum number of decimals, pull out the carriage to the far
right position. Enter the dividend (22) in the far right of the input
unit. Make a positive (clockwise) turn with the crank to transfer
into arithmetic unit.
(2nd) To Set the Divisor into Input Unit:
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Clear the counter.
Enter the divisor (7) above the dividend (22).
(3rd) To Divide:
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Make negative (counter-clockwise) turns with the crank until the
arithmetic unit shows an "underflow". Make one positive (clockwise)
turn with the crank. Move the carriage to the next left position.
Repeat this procedure until the required number of decimals ...
The result (3.1428571) is in the counter unit ( in RED ), and the
remainder (3) is in the arithmetic unit. The divisor (7) stays in the
input unit, therefore an additional decimal can be estimated ...
( 4, cause 4 x 7 = 28).
Have a look at "Calculating Trickies" ...
impressum:
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© C.HAMANN http://public.BHT-Berlin.de/hamann 08/08/09
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