IBM 1403
| Industry | Computer hardware |
|---|---|
| Founded | June 16, 1911 |
| Headquarters | Armonk, New York , United States |
| Products | IBM 1403 line printer, IBM 1401 computer, IBM 1404 printer, IBM 1416 train cartridge |
The IBM 1403 line printer was launched in 1959 as a component of the IBM 1401 computer and remained a durable fixture within the IBM product range for many years.
Description
The initial version of this printer delivers a printing speed of 600 lines per minute and is capable of skipping blank lines at speeds reaching 75 inches per second (190 cm/s). The model 3 variant pushes this performance further, achieving up to 1400 lines per minute. Its standard configuration supports 120 print positions, with an option to add 12 more. The printing mechanism features a horizontally rotating print chain containing multiple copies of the character set, positioned ahead of the ribbon and paper. Printing occurs as hammers strike the paper from behind at precisely timed intervals. Subsequent models replaced the print chain with a print train, where individual print slugs are arranged along a track rather than attached to a chain.
Each chain or train holds 240 characters, with repeated characters allowing the printer to complete a line in less than the full rotation cycle of 0.4 seconds. The original "A" chain included 48 unique characters, each repeated five times. Later "preferred character set" versions adjusted these repetitions: digits appear eight times each, uppercase letters four times each, and special characters vary between two and eight occurrences.
Customized chains were available for specialized applications—for example, scientific symbols could substitute certain special characters. Numeric chains concentrated on fewer characters repeated extensively. The "T" chain supported both uppercase and lowercase letters along with an extensive array of symbols.
The ink ribbon is supplied as a lengthy roll positioned between the print chain and paper. It is continuously advanced during operation by feeder and take-up reels.
Consistent with many IBM printers of its era, the 1403 utilizes fan-folded paper with perforated edges designed for tractor feeding. A carriage control tape or later buffer under program control determines form length and starting line for new pages, allowing compatibility with various paper dimensions.
This printer’s overstrike functionality enables the creation of grey-scale effects by printing multiple layers, which facilitated reproductions of images converted into text—most notably the Mona Lisa.
Operating these machines produces significant noise, especially when open. Interestingly, the timing of hammer strikes can be programmed to generate recognizable melodies during printing.
History
Prior to the introduction of the model 1403, IBM’s printers were based on technology derived from their accounting machines. Models such as the 402 and 405 employed type bars—vertical bars aligned with each print position bearing characters molded on their fronts. Printing involved elevating the correct bar and pressing it against the ribbon to mark the paper, a process limited in speed due to mechanical movement constraints.
The IBM 407 advanced this design by replacing type bars with type wheels that rotated to select the appropriate character before striking the paper. This innovation improved printing speeds up to 150 lines per minute, adequate for electromechanical accounting machines that processed card reading and arithmetic operations. The IBM 1132 was IBM’s final printer utilizing this technology.
As computer technology evolved—with developments such as card readers, magnetic tape storage, and early disk drives—processing speeds increased dramatically, creating a need for faster printing solutions. Early IBM computers like the IBM 701 prioritized rapid calculations but produced minimal printed output. By the time the 1403 was introduced, IBM had segmented its computers into "scientific" and "business" categories; however, emerging applications demanded printing diverse character sets including both upper- and lower-case alphabets. Traditional type bars and wheels were unsuitable for such flexible character requirements.
The chain printer design in the 1403 allowed for swift replacement of its type chain assembly. Opening the cover enabled unlocking and swinging open the print unit; removing the ribbon roll then exposed the print chain assembly for easy removal and replacement within minutes.
At launch, the IBM 1401 system bundled with this printer was leased at $6,500 per month (equivalent to approximately $54,000 in 2017), garnering around 3,000 orders during its initial month on the market.
Technology
Chain printing operates by utilizing a character chain that moves horizontally, with a full-width ribbon positioned vertically between the chain and the paper. Unlike conventional impact printers that strike characters onto the paper, this mechanism employs individual type hammers located behind the paper to push it forward into the ribbon and the character, effectively reversing the traditional impact process. Each hammer is precisely activated by a strong electromagnet coupled with a high-current driving circuit, firing exactly when the corresponding character on the chain is aligned.
Column spacing adheres to the standard 10 characters per inch (0.1″), while characters on the chain are spaced 0.1505″ apart. This arrangement enables new characters to line up with print columns every 0.001″ of chain movement. The chain travels at a speed of 7.5 feet per second, allowing hammers to fire approximately every 11.1 milliseconds, though not all at once.
Models
The IBM 1403 series consists of several models:
- Model 1: Supports 100 print positions, capable of printing up to 600 lines per minute (LPM), or reaching 1285 LPM when equipped with the Numerical Print Special Feature.
- Model 2: Offers 132 print positions with a maximum speed of 600 LPM; this increases to 1285 LPM using the Numerical Print Special Feature and up to 750 LPM with the Universal Character Set.
- Model 3: Features 132 positions and can print up to 1100 LPM; speeds can reach as high as 1400 LPM when using either Preferred or Universal Character Sets.
- Model 4: Provides 100 print positions and prints up to 465 LPM.
- Model 5: Equipped with 132 positions, printing at a maximum of 465 LPM.
- Model 6: Contains 120 positions on a single carriage, with a top speed of 340 LPM.
- Model 7: Also has 120 positions single-carriage, capable of printing up to 600 LPM.
- Model N1: Includes 132 positions and prints at up to 1100 LPM; this can be increased to approximately 1400 LPM with the Universal Character Set. It also features a power-driven cover designed to reduce noise levels.
Attachment compatibility varies among models; only Models 2, 3, 7, and N1 connect to IBM System/360 and subsequent systems—typically through the IBM 2821 Control Unit or integrated control units in certain System/360 machines.
Models 6 and 7 are designed for use with the IBM 1130 system.
IBM 1404
The IBM 1404 is an impact printer that incorporates fundamental features from the IBM 1403 while adding functionality for printing on card documents such as punched cards. It handles continuous forms at a rate of up to 600 lines per minute and processes punched cards at speeds reaching 800 cards per minute. The printer accommodates cards ranging from 51 to 80 columns and can print two cards simultaneously, each supporting up to 25 lines. Additionally, it can read punched cards and reproduce their data in printed form.
Released in 1960 as an accessory for the IBM 1401 system, the IBM 1404 was subsequently adapted for connection with System/360 via an IBM 2821 control unit.
IBM 1416
The IBM 1416 is an interchangeable train cartridge designed for use with the IBM 1403-N1 and IBM 3203 printers. Unlike linked character chains, it consists of a series of unlinked characters arranged in a train format, enabling operators to switch fonts or character sets easily. Customized trains containing unique characters can also be fabricated. While some models of the IBM 1403 include an Interchangeable Train Cartridge Adapter that facilitates quick font changes, this adapter does not possess a distinct machine type classification.