T E C H N I C A L D A T A of the Mechanical Calculator CURTA-1
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* CURTA-1 & CURTA-2 , the world's s m a l l e s t *
* full-functional m e c h a n i c a l calculators ... *
* *
* Be sure to look at ... *
* *
* ===>>> www.CURTA.de , Jan Meyer's exciting Site ... *
* and *
* ===>>> SCIENTIFIC AMERICAN, Jan.2004, p.92-99, Cliff Stoll's *
* "The Curious History of the First Pocket Calculator" *
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Serial Number: 49571
Dimensions: Diameter = 2_1/16" / 53 mm
Height = 4_1/8 " / 105 mm
Weight: 8 oz / 230 g
Mechanics: System Curt Herzstark
Stepped Drum / Staffelwalze
Functions: Add, Subtract, Multiply, Divide
Registers: Input = 8 Decimals
Counter = 6 Decimals
Arithmetic = 11 Decimals
Manufacturer:
CONTINA AG
Vaduz / Liechtenstein
1950
P A R T S of the C U R T A - 1
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Looks different, but works like a big Calculator!
<<<<<
<<<<< for Subtraction, Division
<<<<<---------- pulled up RED MARK shown
<<<<< C R A N K Z (Turns CLOCKWISE only!)
<<<<<---------- pushed down
for Addition, Multiplication
OOOOOOOOOOOOOOO
O O
O CLEARING LEVER can be folded over
OOOOOOOOOOOOOOO when stored into container
+- Decimal MARKERS are shiftable -----------+
| ARITHMETIC UNIT with 11 black dials |
| COUNTER UNIT with 6 white dials |
+->> C A R R I A G E turnable when lifted <<-+
with Position Numbers 11 ... 1
+->> B O D Y Front Side <<-+
| INPUT DIALS 8 ... 1 |
| |
| 0 = up |
| INPUT SLIDERS Z in 8 columns |
| 9 = down |
| |
| SLOT NUMBERS 8 ... 1 |
+--- Decimal MARKERS are shiftable -----------+
+-<< B O D Y Rear Side (not shown) >>-+
| up = normal |
| REVERSING LEVER Z for counting |
+---------------- down = reverse -----------+
H O W T O U S E the CURTA-1
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BEFORE STARTING A TASK:
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All INPUT SLIDERS and the REVERSING LEVER in upper position.
CARRIAGE in position 1. COUNTER and ARITHMETIC UNIT cleared.
CRANK in down position.
ADDITION & SUBTRACTION:
-----------------------
Example: 123 + 45 - 6 = 162
ADD: Enter the first number (123) in the far right columns with
the input sliders. Turn the crank to transfer the number into
arithmetic unit. The counting unit displays the figure 1. Enter
the second number (45). Make a 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). Pull up the crank (red mark
shown) and make a turn. 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:
---------------
Example: 123 x 45 = 5535
Enter the multiplicand (123) in the far right input columns. The
multiplicator (45) has two digits, so the arithmetic unit (in the
carriage) is moved to position 2. Repeat making turns with the
crank, until the first figure of the multiplicator (4) will appear
in the 2nd position of the counter unit. Move the arithmetic unit
to position 1. Repeat making turns with the crank, until the second
figure of the multiplicator (5) appears in the 1st position of the
counter unit. The multiplicand (123) stays in the input dials, the
multiplicator (45) in the counter unit and the result (5535) is in
the arithmetic unit.
DIVISION:
---------
Example: 22 : 7 = 3.14285 Remainder 5
Division requires 3 steps:
(A) To Set the Dividend into Arithmetic Unit:
-----------------------------------------
For the maximum number of decimals, set the arithmetic unit to
the far left position 6. Enter the dividend (22) in the far
right input columns. Make a turn with the crank to transfer
into arithmetic unit.
(B) To Set the Divisor into Input Unit:
-----------------------------------
Clear the counter unit. Shift the reversing lever down.
Enter the divisor (7) below the dividend (22). Pull up the
crank (red mark shown).
(C) To Divide:
----------
Make (subtract) turns with the crank until the arithmetic unit
shows an "underflow". Push down the crank, make one (add) turn
and pull up the crank again. Move the carriage to the next
right position. Repeat this procedure until the required
numbers of decimals are calculated...
The result (3.14285) is in the counter unit, and the
remainder (5) is in the arithmetic unit. The divisor (7) stays
in the input dials, therefore an additional decimal can be
estimated... ( 7, cause 7 x 7 = 49 ).
Have a look at "Calculating Trickies" ...
impressum:
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© C.HAMANN http://public.BHT-Berlin.de/hamann 09/11/09
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