Information about Ibm Selectric

The IBM Selectric typewriter (occasionally known as the IBM Golfball typewriter) is an influential electric typewriter design. It was introduced in 1961.

Instead of a "basket" of pivoting typebars the Selectric had a pivoting type element (frequently called a "typeball") that could be changed so as to display different fonts in the same document, resurrecting a capacity that had been pioneered by the unsuccessful Blickensderfer typewriter sixty years before. The Selectric also replaced the traditional typewriter's moving carriage with a paper roller ("platen") that stayed stationary while the the typeball and ribbon mechanism moved from side to side.

Selectrics and their descendants eventually captured 75 percent of the United States market for electric typewriters.^[1]

Features and uses

The ability to change fonts, combined with the neat regular appearance of the typed page, was revolutionary, and marked the beginning of desktop publishing. Later models with dual pitch (10/12) and built-in correcting tape carried the trend even further. Any typist could produce a polished manuscript. By 1966, a full typesetting version with justification and proportional spacing was released.

The possibility to intersperse text in Latin letters with Greek letters and mathematical symbols made the machine especially useful for scientists writing manuscripts that include mathematical formulae. The typical look of Selectric typed documents is hence still familiar to any scientist who occasionally reads conference proceedings, monographies, theses and the like from these times. (Proper mathematical typesetting was very laborious before the advent of TeX and done only for much-sold textbooks and very prestigious journals.)

The machine had a feature called "Stroke Storage" that prevented two keys from being depressed simultaneously. When a key was depressed, an interposer, beneath the keylever, was pushed down into a slotted tube full of small metal balls (called the "selector compensator") and spring latched. These balls were adjusted to have enough horizontal space for only one interposer to enter at a time. If a typist pressed two keys simultaneously both interposers were blocked from entering the tube. Pressing two keys several milliseconds apart allows the first interposer to enter the tube, tripping a clutch which rotated a fluted shaft driving the interposer horizontally and out of the tube, making way for the second interposer to enter the tube some milliseconds later. While a full print cycle was 65 milliseconds this filtering and storage feature allowed the typist to depress keys in a more random fashion and still print the characters in the sequence entered. The powered horizontal motion of the interposer selected the appropriate rotate and tilt of the printhead for character selection.

The spacebar, dash/underscore, index, backspace and line feed repeated when continually held down. This feature was referred to as "Typamatic."

Design

The Selectric typewriter was first introduced on 31 July 1961 and is generally considered to be a design classic. Its industrial design is credited to Eliot Noyes, an influential American designer. Noyes had worked on a number of design projects for IBM; prior to his work on the Selectric, he had been commissioned in 1956 by Thomas J. Watson, Jr to create IBM's first house style—indeed, these influential efforts, in which Noyes collaborated with Paul Rand, Marcel Breuer, and Charles Eames, have been referred to as the first "house style" program in American business.^[1]

Both Selectric and the later Selectric II were available in standard, medium, and wide-carriage models and in various colors, including red and blue as well as traditional neutral colors.

Mechanically, the Selectric borrowed some design elements from a toy typewriter produced earlier by Marx Toys. IBM bought the rights to the design.^[2]

Selectric II

After the Selectric II was introduced a few years later, the original design was designated the Selectric I. These machines used the same 88-character typing elements. However they differed from each other in many respects:

• The Selectric II was squarer at the corners, whereas the Selectric I was rounder.
• The Selectric II had a Dual Pitch option to allow it to be switched (with a lever at the top left of the "carriage") between 10 and 12 characters per inch, whereas the Selectric I had one fixed "pitch."
• The Selectric II had a lever (at the top left of the "carriage") that allowed characters to be shifted up to a half space to the left (for centering text, or for inserting a word one character longer or shorter in place of a deleted mistake), whereas the Selectric I did not. This option was available only on dual pitch models.
• The Selectric II had an optional correction feature, whereas the Selectric I did not. This worked in conjunction with a correction ribbon: Either the transparent and slightly adhesive "Lift-Off" tape (for use with Correctable Film ribbons), or the white "Cover-Up" tape (for cloth or Tech-3 ribbons). The white or transparent correction tape was at the left of the typeball and its orange take-up spool at the right of the typeball, and was changed independently from the typing ribbon. The correction key (an extra key at the bottom right of the keyboard) backspaced the carriage by one space and also put the machine in a mode wherein the next character typed would use the correction tape instead of the normal ribbon, and furthermore would not advance the carriage. The typist would press the correction key and then re-type the erroneous character, either lifting it off of the page or covering it with white-out powder, then type the correct character. Any number of mistakes could be corrected this way, but the process was entirely manual, as the machine had no memory of the typed characters. Machines with this option were known as "Correcting Selectric II," as if a completely different model.

Ribbons

In addition to the "typeball" technology, Selectrics were also associated with a series of innovations in ribbon design. The original Selectric had to be ordered to use either cloth reusable ribbon or one-time carbon film ribbon; the same machine could not use both. The same was true of the original, non-correcting Selectric II. IBM had used a similar carbon film ribbon on their earlier "Executive" series of typewriters. As with these older machines, the carbon film ribbon presented a security issue in some environments: It was possible to read the text that had been typed from the ribbon, seen as light characters against the darker ribbon background.

The "Correctable" nature of the Correcting Selectric II's carbon film ribbons had an additional issue in that the carbon pigment could easily be removed from a typed document, thus faciliating unauthorized changes.

The Correcting Selectric II used a new ribbon cartridge mechanism. The ribbons were wider than had been used previously, giving more typed characters per inch of ribbon. Successive characters were staggered vertically on the ribbon, which incremented less than a full character position each time. Any Correcting Selectric II could use any of three types of ribbon, which all came in similar-looking cartridges: Reusable cloth ribbon with associated Cover-Up tape; Correctable (carbon) Film ribbon with associated Lift-Off tape; and the Tech-3 permanent ribbon, introduced later, which used the same Cover-Up tape as the earlier cloth ribbon. The Tech-3 ribbon essentially replaced the cloth ribbon, as they offered similar typing quality to the film ribbon but at a cost comparable to the reusable cloth.

Tech-3 ribbons provided much higher security and longer life than the Correctable Film ribbon. Like the cloth ribbon, Tech-3 ribbons incremented only a fraction of the character width after being struck. Unlike the cloth ribbon, the Tech-3 ribbon provided high quality impressions for several characters from each spot on the one-time-use ribbon. Because characters overstrike each other on a Tech-3 ribbon several times it could not be easily read to discover what had been typed.

In addition, where the Correctable Film ribbon was unsuitable for documents such as checks due to the ease of lifting the ink from the document, the Tech-3 ribbon's impressions were permanent as soon as they were struck. Some colored ribbons (e.g. brown) were also available.

Selectric-based machines with data storage

In 1964 IBM introduced the "Magnetic Tape Selectric Typewriter" and in 1969, a "Magnetic Card Selectric Typewriter." These were sometimes referred to as the "MT/ST" and "MC/ST", respectively. The MC/ST was also available in a "communicating" version that emulated an IBM 2741 terminal. These featured electronically-interfaced typing mechanisms and keyboards and a magnetic storage device (either tape in a cartridge, or a magnetic-coated card the same size as an 80-column punch card) for recording, editing, and replaying typed material. These machines were among the first to provide word processing capability in any form. They used the same elements as ordinary office Selectrics.

Selectric Composers

In 1966, IBM released the Selectric Composer. This highly modified Selectric produced camera-ready justified copy using proportional fonts in a number of font sizes and styles. Like the Varityper with which it competed, the machine required that material be typed twice. The first time was to measure the length of the line and count the spaces, recording special measurements on the right margin. The second time it was typed, the operator used the measurements to set justification for each line. The process was tedious and lengthy but provided a way to get camera-ready, proportionally spaced, justified copy from a desktop machine.

The elements for the Selectric Composer would fit on a Selectric, and vice versa, but they could not actually be used on each other's machines: the characters were arranged differently around the element and were also positioned differently within each character area. Selectric Composer elements can be identified by a colored index arrow (the color is used to set a median character width on the machine) and a cryptic series of letters and numbers identifying the font, size, and variation, for example "UN-11-B" for Univers 11 point bold.

In 1967, a "Magnetic Tape Selectric Composer" appeared, and in 1978, a "Magnetic Card Selectric Composer." These used the same elements and measurement mechanism as the previous Selectric Composer; due to the magnetic storage, they avoided the need to type everything twice or to set the mechanism for the justification needs of each line. Furthermore, tapes or cards originally recorded on the much less expensive and easier to operate "Selectric" versions, the MT/ST or MC/ST, could be read by the "Composer" equivalents.

Selectric III

In the 1980s IBM introduced a Selectric III and several other Selectric models, some of them word processors or typesetters instead of typewriters, but by then the rest of the industry had caught up with the trend, and IBM's new models did not dominate the market the way the first Selectric had.

The Selectric III features a 96 character element vs. the previous 88 character element. IBM's series of "Electronic Typewriters" used this same 96 character element. The 96 character elements can be identified by yellow printing on the top plastic surface and the legend "96," which always appears along with the font name and pitch. The 96 and 88 character elements are mechanically incompatible with each other (they won't fit on each others' machines) and 96 character elements were not available in as many fonts as the older 88 character types.

Most Selectric IIIs and Electronic Typewriters only had keys for 92 printable characters; the 96 character keyboard was an optional feature. Fitting the additional keys onto the keyboard required shrinking of the Return key and this was annoying to many typists, so it was not the default configuration. The keytops on the Selectric III and Electronic Typewriters were larger and more square than those on earlier Selectrics.

Elements and fonts

The Selectric I, Selectric II, and all of the "Magnetic Card" and "Magnetic Tape" variations except for the Composers, used the same typing elements. These were available in many fonts, including symbols for science and mathematics, OCR faces for scanning by computers, script, Old English, and more than a dozen ordinary alphabets. The Selectric III and "Electronic Typewriters" used a new 96-character element.

There were two visibly different styles of mechanical design for the elements. The original models had a metal spring clip with two wire wings that were squeezed together to release the element from the typewriter. Later models had a fragile flip-up black plastic lever that could break off. This was later redesigned to have a substantial plastic lever that did not break.

Some of the interchangeable font elements available for the Selectric models included:



Starred fonts were 96-character elements made for the Selectric III.

Many of the fonts listed here came in several sub-varieties. For example, in the early years of the Selectric, typists were used to using the lower-case L for the numeral 1. The Selectric had a dedicated key for 1/!, but this was also marked [/], and many of the early elements had square brackets in these positions, necessitating that the typist continue the old convention. Later elements tended to have the dedicated numeral 1 and exclamation point characters instead. Some moved the square brackets to the positions formerly occupied by the 1/4 and 1/2 fractions, while others lost them completely. Some put a degree symbol in place of the exclamation point. IBM would furthermore customize any element for a fee, so literally endless variations were possible. Such customized elements were identified by a gray plastic flip-up clip instead of a black one.

Many specialized elements were not listed in IBM's regular brochure, but were available from IBM provided the right part number was known. For example, the element for the APL programming language was available. This element was really intended for use with the IBM 2741 printing terminal.

The Selectric as computer terminal

Due to their speed (14.8 characters per second), immunity to clashing typebars, trouble-free paper path, high quality printed output, and reliability, Selectric-based mechanisms were also widely used as terminals for computers, replacing both Teletypes and older typebar-based output devices. One popular example was the IBM 2741 terminal, which figured prominently in the early years of the APL programming language. Similar machines such as the IBM 1050 series were used as the console printers for many computers, such as the IBM 1130 and the IBM System/360 series.

Despite appearances, these machines were not simply Selectric typewriters with an RS-232 connector added. A Selectric is a marvel of mechanical and production—but not electronic—engineering. As with other electric typewriters, and electric adding machines of the era, Selectrics are best thought of as electromechanical devices: The only electric components are the power cord, power switch, and electric motor. The electric motor runs continuously. The keys are not electrical pushbuttons, as they are on a computer keyboard. Pressing a key does not produce an electrical signal, but rather engages a series of clutches which couple the motor power to the mechanism to turn and tilt the element. A Selectric would work equally well if hand-cranked at sufficient speed.

Adapting this mechanism to the needs of computer input/output was therefore nontrivial. The keyboard and printing mechanism were mechanically separated (so that keystrokes do not necessarily result in immediate printing), microswitches were added to the keyboard, solenoids were added to allow the computer to trigger the typing mechanism, and interface electronics were needed. Several mechanical components, in particular the motor and the main clutch, had to be upgraded from the typewriter versions to reliably support continuous operation. Additional microswitches had to be added to sense the state of various parts of the mechanism, such as case (upper vs. lower).

Even after adding all those solenoids and switches, getting a Selectric to talk to a computer was a large project. The Selectric mechanism, as documented in its service manual, had many peculiar requirements. If commanded to shift to upper case when it was already in upper-case, the mechanism locked up and never signaled "done". Same thing for shifting the ribbon direction or initiating a carriage-return. These commands could only be issued at particular times, with the Selectric in a particular state, and then not again until the terminal signaled the operation was complete.

In addition the Selectric spoke neither ASCII nor EBCDIC, but a unique code based on the tilt/rotate commands to the golf ball. That and the bit-parallel interface and peculiar timing requirements meant the Selectric could not be directly hooked up to a modem. Indeed it needed a relatively large amount of logic to reconcile the two devices.

Particularly vexing was the Selectric's lack of a full ASCII character set. The late Bob Bemer wrote^[2] that while working for IBM he lobbied unsuccessfully to expand the typing element to 64 characters from 44. The Selectric actually provided 44 characters per case, but the point remains that with 88 printable characters it could not quite produce the full printable ASCII character set.

Nevertheless, between 1968 and about 1980, a Selectric-based printer was a relatively inexpensive and fairly popular way to get high-quality output from a computer.

The 96-character element introduced with the Selectric III and Electronic Typewriter series could (with some customizations) handle the full ASCII character set, but by that time the computer industry had moved on to the much faster and simpler daisy wheel mechanisms such as the Diablo 630. The typewriter industry followed this trend shortly afterward, even IBM replacing their Selectric lineup with the daisy wheel-based "Wheelwriter" series.

The Selectric in popular culture

• Capitalizing on the then-new Selectric typewriters, the IBM Pavilion at the 1964 New York World's Fair was a large theater shaped and styled like a very-much over-grown Selectric type element. The audience seating area was lifted up into the type element theater for the presentation.
• Hunter S. Thompson was a well known user of Selectric typewriters.
• David Sedaris is a well known user of the Selectric II.
• P. J. O'Rourke says he still uses a Selectric typewriter.
• The American television producer Stephen J. Cannell is a user of Selectric typewriters. His signature clip at the end of many shows depicts him typing on, then pulling a page from, a Selectric II; the scene crossfades to animation wherein the page becomes part of Cannell's company logo.
• A 1963 episode of the Perry Mason TV show, "The Case of the Elusive Element," turned on the fact that the pivoting textball ("element") in Selectric typewriters could easily be switched, making it impossible to know which machine had actually been used to type a message.
• In a 1975 episode of the television show Columbo, "Now You See Him...," Columbo finds evidence of an incriminating document in the carbon film ribbon of a Selectric typewriter.
• In the TV series Mad Men, which is set in the year 1960, Selectric II typewriters are featured prominently on the secretaries' desks, even though they weren't introduced until 1973.

References

External links

• History of IBM typewriters
• History of typewriter design, featuring the Selectric.
• Dead medium: the IBM Selectric Typewriter
• Selectric Typewriter Museum
• The IBM Selectric Composer desktop typesetting system
• The IBM Selectric as a computer I/O device PDF files at Bitsavers.org
• IBM Archives: Office Product Division Highlights