The 407 was the central component of many unit record equipment shops which were the mainstay of IBM's business at the time.

Cards were held in position during each read cycle and the per digit pulses needed were generated using commutators, one for each column.

the first step rotated each wheel to one of 12 groups of characters based on the digit impulse associated with that print position.

The timing of the zone impulse selection was controlled by a complex set of linkages and electromagnets called the Analyzer, one for each of the 120 print positions.

Mechanical systems including the card reader, printer, counters and storage units were all driven by a single motor, which also drove an oil pump and a generator that provided 46-volt power for the electrical logic.

The former had a relay which would inhibit every third card feed cycle (giving the machine a characteristic "shrink-shrink-thunk" sound).

It was possible to insert a folded card between that relay's contacts to "overclock" the slower model to the faster speed.