T E C H N I C A L   D A T A   of the Mechanical Calculator  CURTA-2
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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:   524010

Dimensions:      Diameter  =   2_1/2 " /   65 mm
                 Height    =   4_1/4 " /  110 mm

Weight:             12 oz  /  350 g  =  CURTA-2
                 4_1/2 oz  /  125 g  =  Metal Container

Mechanics:       System Curt Herzstark
                 Stepped Drum / Staffelwalze

Functions:       Add, Subtract, Multiply, Divide

Registers:       Input       =  11 Decimals
                 Counter     =   8 Decimals
                 Arithmetic  =  15 Decimals
Manufacturer:
                 CONTINA AG
                 Vaduz / Liechtenstein
                 1960


       P A R T S          of the         C U R T A  -  2
       *************************************************
       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 15 black dials         |
       |   COUNTER UNIT with 8 white dials             |
       +->>  C A R R I A G E  turnable when lifted  <<-+
                with Position Numbers 15 ... 1

       +->>          B O D Y  Front Side            <<-+
       |     INPUT DIALS    11 ... 1                   |
       |                                               |
       |                      0 = up                   |
       |     INPUT SLIDERS      Z      in 11 columns   |
       |                      9 = down                 |
       |                                               |
       |     SLOT NUMBERS   11 ... 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-2
*********************************

BEFORE STARTING A TASK:
-----------------------
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  =  3.1428571  Remainder 3

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 8. 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 (3.1428571) is in the counter unit, and the
    remainder (3) is in the arithmetic unit. The divisor (7) stays
    in the input dials, 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        06/07/06