Etymology of the word computer

Origin of the word Computer:

Computer is derived directly from the Latin computus and computare.
Both Latin words mean the same as the English verb compute:
Computare = com + putare (Latin root words)
(An intensifying prefix heightens or stresses, but does not change the meaning of the word it modifies
Example: inflammable)

What is a computer
- Computer:
- How was the computer developed/invented:
- The computer is a combination of these 2 ideas.
  The Computer was invented by Alan Turing during World War II (to break the German Enigma code)

Some computing devices invented throughout history

"Ancient" computing device: the abacus

Toy abacus	Real abacus

# beads in row 1 = unit value # beads in row 2 = 10's value # beads in row 3 = 100's value And so on	# beads in column 1 = unit value # beads in column 2 = 10's value # beads in column 3 = 100's value And so on 1 bead in upper half = 5 beads in lower half Value represented by abacus = 63571

Toy abacus

Real abacus

Operation:

The difference engine consists of a number of columns, numbered from 1 to N.
The machine is able to store one decimal number in each column.
The machine can only add the value of a column k + 1 to column k to produce the new value of k.
Column N can only store a constant,
Column 1 displays (and possibly prints) the value of the calculation on the current iteration.

Yours truly have used one of these gadgets when I worked as cashier in my Dad's grocery store:
Not the same model that I used, but it's similar. The device can only add and subtract.
Initially, you press the clear button and pull the lever to reset the running sum to 0.
To add a number to the running sum, you press the black and white buttons to form the number you want to add and pull the lever on the right: the input number is added to the running total. After the addition, the buttons will pop up by themselves (so you can enter a new value to add).
BTW: there is no 0 digit - if you do not press any button in a column, the digit in that column is equal to 0.
If you press the red button, the machine will perform subtraction
You can sorta multiply too: one of the button in the right most column will lock the digits pressed. So after the addition, the same keys will remain "pressed". You can pull the level N times to multiply by N. (So it's only practical if you multiply by a small number, e.g., you will have to pull the level 12345 times if you multiply by 12345....)