A basic system included a model 1402 card reader-punch and a 1403 printer. Bigger systems included model 729 or 7330 tape drives or model 1301, 1311 or 1405 disk drives. Peripherals for data communication, optical character recognition, check sorting, paper tape, ... were available.
Cards can have rectangular holes punched in 80 columns and twelve rows. The top two rows are called 12 and 11, or Y and X. The bottom ten rows are called 0-9. Rows 12 and 11 are called zone rows and rows 0-9 are called numeric rows.
Data are always read into positions 1-80 of memory, and always punched from positions 101-180 of memory.
The printing mechanism consists of a bank of 132 hammers, a ribbon, and a chain of characters. Horizontal spacing of characters is ten per inch. The chain is contained within a removable cartridge. The chain is spun in front of the paper at high speed. When a character on the chain is at a print position at which that character is to be printed, the hammer strikes the paper from the back. The ribbon is positioned between the paper and the chain, resulting in an ink impression of the character when the hammer strikes.
Three standard chains were available. The A chain is for business applications, and the H chain is for scientific applications. These chains had six copies of a 48-character set. With these chains, the printer could print up to 600 lines per minute.
A numeric chain, having eighteen copies of only the digits plus six special characters allowed printing at up to 1200 lines per minute.
Characters having 5-8, 6-8 or 7-8 representations (with or without zones) cannot be printed without special chains. The representations of the A and H chains, in Paul Pierce's ASCII encoding of BCD tapes, are
8421 in hex, A chain 8421 in hex, H chain
Zone BA | 0 1 2 3 4 5 6 7 8 9 A B C D E F | 0 1 2 3 4 5 6 7 8 9 A B C D E F
none 00 | 1 2 3 4 5 6 7 8 9 0 # @ : > { | 1 2 3 4 5 6 7 8 9 0 = ' : > {
zero 01 | ^ / S T U V W X Y Z | , % ~ \ " | ^ / S T U V W X Y Z | , ( ~ \ "
11 10 | - J K L M N O P Q R ! $ * ] ; _ | - J K L M N O P Q R ! $ * ] ; _
12 11 | & A B C D E F G H I ? . ) [ < } | + A B C D E F G H I ? . ) [ < }
The only differences here are B-A (12) [&,+], 3-8 [#,=], 4-8 [@,'] and
A-4-8 (0-4-8) [%,(]. On a real A chain, B-A-4-8 (12-4-8) printed as a
character named "lozenge," a little box with pointed corners.
Data are always printed from memory positions 201-332.
The paper advance mechanism can be set to advance paper at six or eight lines per inch. It can also skip to a position indicated by a punch on a paper control tape at 75 inches per second.