Adding machine

In the United States, the earliest adding machines were usually built to read in dollars and cents.

Adding machines were ubiquitous office equipment until they were phased out in favor of electronic calculators in the 1970s and by personal computers beginning in about 1985.

[1] For Pascal, this was an adding machine that could perform additions and subtractions directly and multiplication and divisions by repetitions, while Schickard's machine, invented several decades earlier, was less functionally efficient but was supported by a mechanised form of multiplication tables.

These two were followed by a series of inventors and inventions leading to those of Thomas de Colmar, who launched the mechanical calculator industry in 1851 when he released his simplified arithmometer (it took him thirty years to refine his machine, patented in 1820, into a simpler and more reliable form).

The user would then pull the crank, which caused the numbers to be shown on the rotary wheels, and the keys to be released (i.e. to pop back up) in preparation for the next input.

The rotary wheels now show a running 'total' of 3521 which, when interpreted using the decimal currency colour-coding of the key columns, equates to 35.21.

Division was also possible by putting the dividend to the left end and performing repeated subtractions by using the complementary method.

The user now pressed the multiplication 0 key which caused tabulation of the adding mechanism one more column to the right, but did not cycle the machine.

To see the total the user was required to press a Total key and the machine would print the result on a paper tape, release the locked down keys, reset the adding mechanism to zero and tabulate it back to its home position.

He was a founder of American Arithmometer Company, which became Burroughs Corporation and evolved to produce electronic billing machines and mainframes, and eventually merged with Sperry to form Unisys.