
IBM 5250 is a family of
block-oriented terminal
A computer terminal is an electronic or electromechanical computer hardware, hardware device that can be used for entering data into, and transcribing data from, a computer or a computing system. Most early computers only had a front panel to ...
s originally introduced with the
IBM
International Business Machines Corporation (using the trademark IBM), nicknamed Big Blue, is an American Multinational corporation, multinational technology company headquartered in Armonk, New York, and present in over 175 countries. It is ...
System/34 midrange computer
Midrange computers, or midrange systems, were a class of computer systems that fell in between mainframe computers and microcomputers.
This class of machine emerged in the 1960s, with models from Digital Equipment Corporation ( PDP lines), Data ...
systems in 1977. It also connects to the later
System/36
The IBM System/36 (often abbreviated as S/36) was a midrange computer marketed by IBM from 1983 to 2000 - a multi-user, Computer multitasking, multi-tasking successor to the IBM System/34, System/34.
Like the System/34 and the older IBM Syst ...
,
System/38
The System/38 is a discontinued minicomputer and midrange computer manufactured and sold by
IBM. The system was announced in 1978. The System/38 has 48-bit computing, 48-bit addressing, which was unique for the time, and a novel database#Integrat ...
, and
IBM AS/400
The IBM AS/400 (Application System/400) is a family of midrange computers from IBM announced in June 1988 and released in August 1988. It was the successor to the System/36 and System/38 platforms, and ran the OS/400 operating system. Lower-cost b ...
systems, and to
IBM Power Systems
IBM Power Systems is a family of server computers from IBM that are based on its Power processors. It was created in 2008 as a merger of the System p and System i product lines.
History
IBM had two distinct POWER- and PowerPC-based hardwa ...
systems running
IBM i
IBM i (the ''i'' standing for ''integrated'') is an operating system developed by IBM for IBM Power Systems. It was originally released in 1988 as OS/400, as the sole operating system of the IBM AS/400 line of systems. It was renamed to i5/OS in 2 ...
, as well as the
Series/1 minicomputer
A minicomputer, or colloquially mini, is a type of general-purpose computer mostly developed from the mid-1960s, built significantly smaller and sold at a much lower price than mainframe computers . By 21st century-standards however, a mini is ...
.
Components
5250 devices can be directly attached to the
host
A host is a person responsible for guests at an event or for providing hospitality during it.
Host may also refer to:
Places
* Host, Pennsylvania, a village in Berks County
* Host Island, in the Wilhelm Archipelago, Antarctica
People
* ...
or communicate remotely using
Synchronous Data Link Control
Synchronous Data Link Control (SDLC) is a computer serial communication, serial communications protocol first introduced by IBM as part of its Systems Network Architecture (SNA). SDLC is used as layer 2, the data link layer, in the SNA protocol s ...
(SDLC) at up to 9600bit/s. Devices can also be clustered or
daisy-chained.

In 1980 the 5250 system consisted of the following components:
* 5251 Display Station. The monochrome text-only display can be either 960 characters, formatted as 12 lines of 80 characters, or 1920 characters as 24 lines of 80 characters. Upper and lower case is standard. Text attributes consist of blink, high intensity, reverse video, non-display, underscore, and a unique ''column separator'' that causes the field to be preceded and followed by a vertical bar. 5251 and 5252 input ''format control'' attributes are optimized for data entry applications and offer significant enhancements over previous 3270 terminals.
* 5252 Dual Display Station. The 5252 features a single
CRT
CRT or Crt most commonly refers to:
* Cathode-ray tube, a display
* Critical race theory, an academic framework of analysis
CRT may also refer to:
Law
* Charitable remainder trust, United States
* Civil Resolution Tribunal, Canada
* Columbia ...
displayed 12 lines each on two different sides back to back in a single case, with separate keyboards. The 5252 was not part of the initial announcement.
* 5256 printer. The 5256 is a tabletop serial
dot matrix printer
Dot matrix printing, sometimes called impact matrix printing, is a computer printing process in which ink is applied to a surface using a relatively low-resolution dot matrix for layout. Dot matrix printers are a type of impact printer that p ...
with three models providing speeds of 40, 60, or 120cps and a print line of 132 characters.
5251/5252 format control
Field attributes also define the type of data the operator can enter into a field, and specify other control information for the field.
* A field can be defined as alpha only, numeric only, or
alphanumeric
Alphanumericals or alphanumeric characters are any collection of number characters and letters in a certain language. Sometimes such characters may be mistaken one for the other.
Merriam-Webster suggests that the term "alphanumeric" may often ...
.
*''Auto enter'' simulates an ''ENTER'' key press at the conclusion of the field.
*''Bypass'' automatically skips over a field in the screen.
*''Duplicate enable'' allows the operator to press the ''DUP'' key in a field, entering a special code which is interpreted by the application program – typically duplicating data in this field from the previous record or line.
*''Field exit required'' forces the operator to manually exit this field, rather than automatically advancing to the next field after entering the last character.
*''Mandatory entry'' specifies that the operator
must enter data in this field and is not allowed to tab over it.
*''Monocase'' translates lower-case characters entered into this field to upper-case.
*''Mandatory fill'' specifies that this field must be entirely filled if any data is entered into it.
*''Right adjust'' will right adjust data entered in a field when the operator exits the field.
*''Signed numeric'' reserves the rightmost position of a field for a sign – blank for positive or '-' for negative.
Terminal status lights
On a 5251 type terminal featured five status lights on the front of the unit:
* ''System Available light'': If lit, this terminal is connected to the host system and is receiving information from it.
* ''Message Waiting light'': Other users, and the system itself, can send messages to
workstation
A workstation is a special computer designed for technical or computational science, scientific applications. Intended primarily to be used by a single user, they are commonly connected to a local area network and run multi-user operating syste ...
s. If lit, there is at least one message that has not been seen yet. When a program ends or when the user signs on, the message(s) will be shown.
* ''Insert light'': The
Insert key
The Insert key (often abbreviated Ins) is a key commonly found on computer keyboards.
It is primarily used to switch between the two text-entering modes on a personal computer (PC) or word processor:
* overtype mode, in which the cursor, whe ...
has been pressed. Characters after the cursor will shift right when text is keyed. Press Insert again to cease Insert Mode.
* ''Caps Lock light'': The
Caps Lock key has been pressed.
* ''Keyboard Shift light'': The
Shift key
The Shift key is a modifier key on a alphanumeric keyboard, keyboard, used to type majuscule, capital letters and other alternate "upper" characters. There are typically two Shift keys, on the left and right sides of the row below the home row. T ...
is being pressed.
Historical origins
The 5250 is a block-oriented terminal similar to, but not compatible with, the
IBM 3270
The IBM 3270 is a family of Block-oriented terminal, block oriented display and printer computer terminals introduced by IBM in 1971
and normally used to communicate with IBM mainframes. The 3270 was the successor to the IBM 2260 display ter ...
. Robustly constructed, 5251 terminals weigh roughly . The devices generate an audible clicking sound as the user types, similar to the
electronic typewriters of the era.
The 5250 data stream definition has been refined over time to include
GUI elements such as pop-up windowing, check and option boxes, mouse handling, and
pull-down menu
In user interface design, a menu is a list of options presented to the user.
Navigation
A user chooses an option from a menu by using an input device. Some input methods require linear navigation: the user must move a cursor or otherwise pas ...
s. The IBM 3180 added support for seven colors - pink, red, blue, yellow, green, white, and turquoise. A protocol called the IBM 5250 Data Stream interpreted field attributes such as blinking, non-display, high intensity, reverse image, underline, and column separators and was used in combination to create colors. Normal text was presented as green on a 3180 color terminal, but high intensity became white. Column separators became yellow. Blinking became red. Underlined text was presented as blue. High intensity blinking became pink. High intensity column separators became turquoise.
The term "5250" now refers to the data stream itself. No physical 5250 terminals with their bulky
twinax cables still exist, although they were occasionally still used to provide a "connection of last resort," hard-wired to the host computer. Today, it is more common to use PC or web-based terminal emulation packages that can interpret and display 5250 data streams.
Telnet 5250

Telnet 5250, or TN5250 describes either the process of sending and receiving 5250 data streams using the
telnet
Telnet (sometimes stylized TELNET) is a client-server application protocol that provides access to virtual terminals of remote systems on local area networks or the Internet. It is a protocol for bidirectional 8-bit communications. Its main ...
protocol or the software that emulates a 5250 class terminal communication via that process. TN5250 allows a 5250
terminal emulator
A terminal emulator, or terminal application, is a computer program that emulates a video terminal within some other display architecture. Though typically synonymous with a shell or text terminal, the term ''terminal'' covers all remote term ...
to communicate over a
TCP/IP
The Internet protocol suite, commonly known as TCP/IP, is a framework for organizing the communication protocols used in the Internet and similar computer networks according to functional criteria. The foundational protocols in the suite are ...
network instead of an
SNA network. Standard telnet clients cannot be used as a substitute for TN5250 clients, as they use a different data stream format.
Interfacing 5250 terminals with commodity hardware
An interface was created to connect to the Twinax port of a 5250 terminal and communicate with it like an AS/400 host.
It currently provides
VT52
The VT50 is a CRT-based computer terminal that was introduced by Digital Equipment Corporation (DEC) in July 1974. It provided a display with 12 rows and 80 columns of upper-case text, and used an expanded set of control characters and forwar ...
emulation and a shell on the system to which the adapter is connected.
List of IBM 5250 Twinax terminals
IBM 3179
The IBM 3179 exists as a
3270 and a 5250 terminal.
IBM 3180
The IBM 3180 exists as a
3270 and a 5250 terminal.
IBM 3196
80x24 characters.
Models:
* 3196 model A10: Green screen.
* 3196 model B10: Amber-Gold screen.
IBM 3197
Models:
* IBM 3197 model C10 (1920 characters)
* IBM 3197 model C20 (1920 characters)
* IBM 3197 model D10 (3564 characters)
* IBM 3197 model D20 (3564 characters)
* IBM 3197 model D40 (15 inch green phosphor)
IBM 3476
IBM 3477
Models:
* IBM 3477 model HAX (14-inch amber-gold monochrome monitor)
* IBM 3477 model HGX (14-inch green monochrome monitor)
* IBM 3477 model HCX (14-inch color monitor)
* IBM 3477 model HDX (15-inch green monitor)
IBM 3486
Models:
* IBM 3486 model BAX (14-inch amber-gold monitor)
* IBM 3486 model BGx (14-inch green monitor)
IBM 3487
Models:
* IBM 3487 model HAX (15-inch amber-gold monitor)
* IBM 3487 model HCX (14-inch color monitor)
* IBM 3487 model HGX (15-inch green monitor)
IBM 3488
Does not include an internal display. An external monitor is connected via
VGA
Video Graphics Array (VGA) is a video display controller and accompanying de facto graphics standard, first introduced with the IBM PS/2 line of computers in 1987, which became ubiquitous in the IBM PC compatible industry within three years. T ...
.
IBM 3489
Does not include an internal display. An external monitor is connected via VGA.
See also
*
Terminal emulator
A terminal emulator, or terminal application, is a computer program that emulates a video terminal within some other display architecture. Though typically synonymous with a shell or text terminal, the term ''terminal'' covers all remote term ...
*
IBM 3270
The IBM 3270 is a family of Block-oriented terminal, block oriented display and printer computer terminals introduced by IBM in 1971
and normally used to communicate with IBM mainframes. The 3270 was the successor to the IBM 2260 display ter ...
References
External links
Overview of the green screen (5250 Terminal)*
* – 5250 Telnet Interface
* – 5250 Telnet Enhancements
* {{IETF RFC, 4777 – IBM's iSeries Telnet Enhancements
5250
Block-oriented terminal
5250
Computer-related introductions in 1977