The IBM 1403 line printer was introduced as part of the IBM 1401 computer in 1959 and had an especially long life in the IBM product line. Description The original model can print 600 lines of text per minute and can skip blank lines at up to 75 inches per second (190 cm/s), while the model 3 can print at up to 1400 lines per minute. The standard model has 120 print positions. An additional 12 positions are available as an option. A print chain with up to 15 copies of the character set spins horizontally in front of the ribbon and paper. Hammers strike the paper from behind at exactly the right moment to print a character as it goes by. In later models, the print chain is replaced by a print train; print slugs instead of being mounted on a chain are placed in a track. 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 original standard "A" chain contains 48 different characters, repeated five times each. A "preferred character set" variant used in later models prints the same 48 characters, but varies the number of appearances: 10 digits appear eight times each, 26 upper-case letters appear four times each, and 12 special characters . , - * % $ / & # @ ⌑ ⧧ appear eight (first four), four (middle four) or two (last four characters) times each. Special chains or trains can be ordered for other character sets. Scientific users, for example, can use a chain that has the left parenthesis, the right parenthesis, and the plus sign in place of the per cent sign (%), the lozenge (⌑), and the ampersand (&). The numerics chain has 15 copies each of only 16 characters. The "T" chain for general text has two copies of 120 characters, including upper-and lower-case letters and numerous special symbols. The ink ribbon is a long roll the width of the print area positioned between the print chain and the paper. The roll comes in two parts: the feeder roll and take-up roll. The roll is constantly wound and rewound during printing. Like most IBM printers of the era, the 1403 uses fan-folded paper with perforated edges for tractor feeding. A carriage control tape or, later, a buffer, under program control,