characters per inch, 0.1″ per column. The characters on the chain are spaced 0.1505″ apart, so that for each 0.001″ movement of the chain, a new character aligns with a print column. Moving at 7.5 feet per second, one hammer might fire each , but they were never exactly simultaneous. Character set Models The IBM 1403 has the following models: Model 1: 100 print positions, maximum of 600 lines per minute, or 1285 with the Numerical Print Special Feature. Model 2: 132 print positions, maximum of 600 lines per minute, or 1285 with the Numerical Print Special Feature, or 750 with Universal Character Set. Model 3: 132 print positions, maximum of 1100 lines per minute, or 1400 with the Preferred or Universal Character Sets. Model 4: 100 print positions, maximum of 465 lines per minute. Model 5: 132 print positions, maximum of 465 lines per minute. Model 6: 120 print positions, maximum of 340 lines per minute, single-carriage. Model 7: 120 print positions, maximum of 600 lines per minute, single-carriage. Model N1: 132 print positions, maximum of 1100 lines per minute, or 1400 with Universal Character Set. The model N1 has a power-driven cover that reaches the floor to decrease noise. Only models 2, 3, 7 and N1 can be attached to the IBM System/360 and its successors. Attachment is generally by means of the IBM 2821 Control Unit, but some 360 models include an integrated control unit for direct 1403 connection. Only the Model 6 (340 LPM) or the Model 7 (600 LPM) can be attached to an IBM 1130. IBM 1404 The 1404 printer is an IBM impact printer with "all the basic features of the IBM 1403 Printer," with the added ability to print on card documents, such as punched cards. The 1404 can print on continuous forms at 600 lines per minute, and on cards at 800 cards per minute. The mechanism can handle cards ranging from 51 columns to a full 80 columns, and can print cards two at a time. Up to 25 lines can be printed on a card. The printer can also interpret cards, that is, read the card and print what was punched. The 1404 was originally introduced in 1960 as a peripheral for the IBM 1401 computing system. It was later able to attach to a System/360 through an IBM 2821 control unit. IBM 1416 The IBM 1416 is an