P/N 4941831 - Model B Keyboard Details & Specs
| Known Assembly Part NumbersKnown Assembly Part Numbers Possible numbers found inside this keyboard used to indicate its internal assembly and the keycaps on it. |
1650737 |
| TypeType A designation from my own type naming scheme used to categorise this keyboard with or from others by their common features and market intent but may/may not be derived from official names. |
Model B 3251/3276/3278/3279/8775 75-key Base Keyboard |
| OEMOEM Possible companies responsible for making this keyboard for the company marketing it. |
IBM |
| Key-switchesKey-switches The name of the known switching mechanism that lies under this keyboard's keys. |
IBM beam springs |
| Earliest AppearanceEarliest Appearance The year (and possibly the quarter) that this keyboard part number was introduced, first observed, first recorded or the first example found. |
1979 Q3 |
| Original KeycapsOriginal Keycaps The keyboard's original keycaps' material and text/symbol printing technique. |
SAN with double-shot legends |
| Casing ColourCasing Colour The original colour of this keyboard's outer casing. For keyboards whose casing materials are known to yellow, this will refer to the original colour before such transformation occurs. |
Pearl White |
| BrandingBranding The possible branding and logo styles found on this keyboard part number. This could be multiple styles at once or possible styles found over time. |
None |
| FeetFeet The style of this keyboard's flip-out or extendable feet. If applicable, this may also state how many levels of height adjustment are available and whether the feet could be rubberised. |
None |
| ConnectionConnection The keyboard-to-host connection. This is could be a description of a cable (its colour, whether its coiled, whether its detachable, and what connector is at its end) or the name of a wireless technology. |
Black straightened-style fixed DB-25 cable |
| Key CountKey Count The number of keys that this keyboard originally had. |
76 |
Layout/LanguageLayout/Language The original regional/language layout this keyboard was configured as. Both the language and the standardised key layout may be listed, and in the case of both being known or defined, it will be styled as language then standard. |
Japan/English; Typewriter |
| Source(s)Source(s) Documents ("Doc"), websites and/or webpages ("Web") that were used as a source of information for this keyboard part number. Examples of this keyboard part number I own ("ASK") will also be included as sources. |
Doc: IBM 3270 Information Display System 3276/3278 Keyboard Assembly Parts Catalog (#S126-0029-0) [source: bitsavers] |
| Data Last Updated | 2021-11-19 |
More on this type of keyboard...
The IBM 3276 Control Unit Display Station and 3278 Display Station were the second generation of IBM 3270 Information Display System coaxial cable display terminals that first appeared in May 1977, succeeding the IBM 3275 and 3277 Display Stations respectively as standard terminals for IBM System/370 and compatible mainframes. The 3276 was a dual-purpose terminal like the 3275 that had an integrated control unit that could control up to seven additional display stations and printers for remote communications. The 3278 like the 3277 was just a terminal. Both the 3276 and 3278 were available in models with 960, 1920, 2560 or 3440 character displays. Joining them on 17th November 1977 was the IBM 3250 Graphics Display System and its IBM 3251 Display Station, which provided interactive graphics capabilities for CAD/CAM, architectural, simulation and mapping applications to System/370 and compatible mainframes. The IBM 8775 Display Terminal was an "intelligent" terminal that attached to the IBM 8100 Information System and was introduced alongside it in October 1978. The 8775 was a serial terminal and was notable for introducing multiple partitioning, which was a feature that allowed the user to define up to 8 rectangular separations for displayed data. Finally, the IBM 3279 Color Display Station was introduced in 1979 and was IBM's first colour terminal. The 3279 resembled the 8775 from the outside but was in fact a 3270 coaxial terminal that depending on the model had a 1920 or 2560 character display supporting 4 "base" colours or 7 "extended" colours.
The 75-key keyboard was the smaller of the two "late 3270" keyboards. Due to its widespread adoption across many terminals, there were subsequently many possible versions of this keyboard including ones with ASCII Typewriter, EBCDIC Typewriter, EBCDIC Data Entry or EBCDIC IBM Card Punch-style Data Entry layouts. Typewriter and data entry keyboards could be distinguished from each other by the latter's characteristic use of an overlay numeric keypad and scattered black program function ("PFxx") keys. Typewriter keyboards were designed to facilitate both upper and lower-case character input and had a shift lock key, whereas data entry keyboards were designed for uppercase-only input but had numeric and alphabetic shift keys. Additionally, two sub-types of 76-key keyboards were available for specific layouts and functions. The standard 76-key keyboard was intended for (IBM World Trade Americas/Far East Corporation) Japanese English Typewriter, Japanese Katakana Typewriter or Japanese Katakana Data Entry layouts. This 76-key keyboard gained the extra key in the top-left corner relative to the return key; to accommodate this, compared to the 75-key keyboard, the 76-key physical layout extended the width of the keys on the right side of the main alphanumeric key sections at the expense of the left side keys. An RPQ 76-key version of the data entry keyboard was available with an "adding machine" layout which differed from the Japanese 76-key keyboard since it gained an extra key from a split spacebar instead, allowing for its characteristic large "0" key on the bottom row. The adding machine layout was similar to "proof arrangement" keyboards for other terminal families in that it had a reversed order overlay numeric keypad (U, I, and O were 7, 8 and 9 respectively instead of 1, 2 and 3).
Late 3270 series keyboards characteristically had black cables with a right-angle male DB-25 plug and grounded screw bracket on its end, as well as an access panel in its palm rest that stored the host terminals' Problem Determination Guide for convenience. Late 3270 keyboards also had a solenoid inside that was used as a "keyboard clicker". In normal operation with their original host terminals, the clicker would engage as an audible confirmation for a registered key. The clicker could be toggled on or off with the bottom-right-most key of the left 4x2 key bank. If the clicker feature was turned off by the user, the solenoid could still be used for notifying the user when they try to press a key whilst the keyboard had been disabled by the terminal. Contrary to the common belief that this keyboard was the "3276 keyboard", cross-referencing with IBM parts catalogues reveals that IBMs 3276, 3278 and 3279 for the most part shared the same pool of keyboards and keyboard part numbers for this type.
