A print chain with up to 15 copies of the character set spins horizontally in front of the ribbon and paper.

The 1403 chain or train contains 240 characters, however numerous duplications allow a line to be printed in less than the 0.4 s required for one full rotation.

The "T" chain for general text has two copies of 120 characters, including upper-and lower-case letters and numerous special symbols.

Like most IBM printers of the era, the 1403 uses fan-folded paper with perforated edges for tractor feeding.

The overstrike capability of the printer can be used to generate a wide range of grey-scale equivalents.

[4] Prior to the introduction of the model 1403, IBM printers utilized technology originally developed for their line of accounting machines.

This action is relatively slow, as it took time for each bar to be brought up into the correct position and then drop back down in preparation to print the next line.

This action is somewhat faster because the wheels are less massive than the bars and can be positioned more rapidly, allowing printing at up to 150 lines per minute.

With the cover open, the print unit is unlatched and swung open, the ribbon roll covering the front of the chain is removed, whereupon the print chain assembly can be unlatched and lifted out.

Each hammer is moved by a powerful electromagnet, with its coil connected to a high current drive circuit, such that the hammer can be forced out to hit the paper within only a few milliseconds, at exactly the right time to strike the correct character on the chain as it came by.

[9]: 26 [10]: 46 IBM provided software support for impact printers with interchangeable print elements, e.g., chains, trains.

The control unit has a UCS buffer[note 5] containing the code point for each position of the print element.

The cartridge allows the operator to change the font and/or character set arrangement being used by the printer.

Note that while the IBM 1403 Models 2 and 7 do offer a feature known as the Interchangeable Train Cartridge Adapter, which allows the operator to easily remove and insert a chain cartridge with a different font or character set arrangement, this feature does not have a separate machine type.