Odhner
From Hackbox
Contents
Specification
- Original Odhner Arithmos pinwheel calculator
- Serial 41603 (estimated from the late 1920's)
- 9 decimals input
- 13 decimals accumulator
- 8 decimals counter
Origin
Donated in 2013.
Condition
Generally works, but:
- a lot of the digits have lost their paint.
- there seems to be a part missing to shift the carriage. there are some holes and pictures of similar models show buttons to advance the carriage by one position left or right.
Usage Hints
- Input is given by setting the 9 levers.
- The right hand counter is the accumulator. It stores the result of the addition or subtraction.
- The left hand counter is the register. It counts the number of turns.
- Input is transferred to the accumulator by turning the crank, clockwise turn for addition, counter-clockwise for subtraction.
- The carriage can be shifted to align the input with a certain decimal of the accumulator and the register.
- Both register and accumulator have a reset handle, give it a full turn to set all digits to zero.
- The input can be easily reset by pulling the reset handle left while turning the crank until it pushes all levers to zero.
- (other than the above) always turn the crank a full turn. You can always undo a turn by turning in the opposite direction.
- A bell signals an overflow condition.
Addition
- Reset accumulator
- Input the first operand.
- Turn clockwise.
- Input the second operand.
- Turn clockwise.
- Read result from accumulator.
Subtraction
- Reset accumulator
- Input the first operand.
- Turn clockwise.
- Input the second operand.
- Turn counter-clockwise.
- Read result from accumulator.
Multiplication
- Reset accumulator and register.
- Shift carriage all the way to the left.
- Input the first factor.
- Turn clockwise as many times until the last decimal in the register equals the last digit of the second factor.
- Shift the carriage 1 position to the right.
- Turn clockwise as many times until the fore-last decimal in the register equals the fore-last digit of the second factor.
- Repeat the last two steps for all digits of the second factor.
- Read the product from the accumulator.
Division
- Reset accumulator
- Shift carriage to the right, allowing space for decimals.
- Input the dividend.
- Turn clockwise to transfer it to the accumulator.
- Reset the register.
- Input the divisor.
- Shift carriage to align the leading digits of input and accumulator.
- Keep turning counter-clockwise until the bell rings.
- Turn clockwise to undo the last turn.
- If accumulator contains all zeros, read exact quotient from register, else shift carriage one position left and repeat last two steps.
- If not dividable, the process stops when the carriage is all the way to the left. Read approximate quotient from the register and remainder from the accumulator.
Square root
- Reset accumulator
- Shift carriage all the way to the right.
- Input number
- Turn clockwise to transfer it to the accumulator
- Reset register
- Shift carriage aligning left-most digit of input with left-most digit of the value in the accumulator
- Set a 1 in the input that is aligned with the right-most digit of the value in the accumulator and turn counter-clockwise
- Set the next odd number (3) and turn counter-clockwise
- Repeat with next odd numbers (5, 7, 9, 11, 13, ...) until the bell rings.
- Undo last turn by turning clockwise.
- Subtract 1 from input
- set a 1 in the next input digit (one decimal to the right)
- shift carriage left.
- repeat the process of subtracting odd numbers until the bell rings.
- If accumulator contains all zeros, read exact result from register
- If carriage reaches left-most position, read approximate result from register