P/N 4942028 - Model B Keyboard Details & Specs

Provided by the ASK Keyboard Part Number Database

IBM 3278/3279 Display Console 75-key Operator Console Keyboard without Num. Lock

Known Assembly Part NumbersKnown Assembly Part Numbers
Possible numbers found inside this keyboard used to indicate its internal assembly and the keycaps on it.
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 3276/3278/3279 75-key Operator Console Keyboard
Known Host SystemsKnown Host Systems
A list of known host systems this keyboard could be bundled with or at least designed specifically to operate with. This could be terminals, desktop PCs or laptops.
IBM 3278 Model 2A Display Console (IBM 3270 family)
IBM 3279 Model 2C Color Display Console (IBM 3270 family)
Possible companies responsible for making this keyboard for the company marketing it.
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 (w/ possible pad-printed front-printed 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
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.
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.
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.
Image of Layout/LanguageThe 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.
Austria/Germany; OCP typewriter w/o channel-to-channel feature
Accessories & Other FeaturesAccessories & Other Features
Other notable features you may want to know about such as charging cables (if keyboard is wireless), fingerprint reader, card reader, solenoid, DIP switches, etc.
Clicker assembly (internal solenoid)
Compartment for host computer's/terminal's guide
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]
Related Directory EntriesRelated Directory Entries
Possible ASK Keyboard Directory entries that relate to this part number. The Directory serves as a convenient way to find and share a particular keyboard, containing links to where to find out more about the keyboard and sometimes common part numbers.
IBM 3278/3279 Display Console 75-key Operator Console Keyboard without Num. Lock (IBM 43X1 w/o channel-to-channel)
Data Last Updated 2023-12-27

More on this type of keyboard...

Variant of a Model B 3276/3278/3279 75-key Operator Console Keyboard

The IBM 3278 Model 2A Display Console and 3279 Model 2C Color Display Console were variants of the 3278 Display Station and 3279 Color Display Station respectively designed for operator console usage, replacing the plethora of various dedicated operator consoles for past IBM System/370 mainframes. They seemed to be primarily associated with IBM 43X1 series Processors, which were mid-range System/370 compatible processing units. 3278-A2 (sometimes misprinted as "3278-A02") was used with IBM 4331 and 4341 processors from January 1979, and 3279-2C was used with later 4361 and 4381 Processors from 1983. The 3278-2A at least was then used with IBM 308X series mainframes such as the IBM 3081 Processor Complex from November 1980, which were System/370-compatible processing units that introduced the IBM System/370 Extended Architecture. The operator consoles were used for controlling power and processor operation. According to IBM parts catalogues, the keyboard used for both 3278-2A and 3279-2C may also be available for the IBM 3276 Control Unit Display Station in some capacity. They were succeeded by IBM 3205 and 3206 Display Consoles that used 122-key Model F or Model M keyboards.

The 'late 3270 series' Operator Console Keyboard - also known as the IBM 3276/3278/3279 Keyboard with Operator Control Panel (OCP) - was a unique variant of the standard 327X-75 type Model B that combined a basic typewriter-style keyboard with OCP functionality that used to exist as a separate panel on the front of IBM System/370 Processing Units. Whilst this concept had been practised since the very beginning of Model B keyboards with 1972's S370-T1 type (and previous 3270 series terminals such as the 3275 and 3277 had a 78-key operator console keyboard), this brought a keyboard with an OCP mounted on it into the 3270 family. The 3270 OCP keyboard with its display console was used for entering data, answering program-generated requests, performing manual functions and entering control information into the host system directly. Like many previous non-3270 family operator console keyboards, 3270 OCP keyboards had green "START" and red "STOP" keys that were used for controlling instruction processing. The OCP above the keyboard was used as a quick control and monitor instrument that could allow an operator to control system power, load support processor microcode, observe system status, and the control channel-to-channel (an adapter to synchronise the data path between two processors) feature. The exact composition of controls and the black shroud surrounding them were subject to variants because, for example, not every processor had the Channel-to-Channel feature, thus didn't need a control for it. At least 4 variants are currently recognised:

1. IBM 43X1 with Channel-to-Channel control

2. IBM 43X1 without Channel-to-Channel control - OCP has a grey, blue and red button that are all surrounded by a raised shroud

3. IBM 43X1 without Channel-to-Channel and power-on controls - OCP has a grey, blue and red button with the latter separated by two raised pieces either side

4. IBM 308X with "SCCP" - OCP reads "PC Power" and has one grey and two blue buttons, with each surrounded by its own raised border

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. Internally, the OCP component is separate to the keyboard assembly and its electronics, so it had its own cable also terminating in a DB-25 plug. 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.