IBM 3270
3270 is the name for a series of terminals from IBM. The first screen terminal type 3270 were presented for the first time to the public in 1971, and made available from 1972. They replaced the formerly standard typewriter terminals with the output medium continuous paper. In addition to the hardware, the numeral 3270 and the protocol used to transmit the data at this point.
The model 3270 made it possible for large-scale online applications introduce. The screen could programmatically formatted input and output fields are defined. After the user actions, only the changed data to be forwarded. The inputs of the user were buffered in the device or in a control unit and transmits only after pressing the Enter key or a function key to the host.
The first 3270 models were monochrome and texts supported with single or double brightness. In addition, could be defined fields without visible text ( for example, for entering passwords ). Later, color screens (8 colors ), inverse display, underlined text and blinking text were supported. The number of function keys has been increased from 12 to 24 and in addition to the standard models with a resolution of 24 × 80 characters originated those with 32 × 80, 43 × 80 and 27 × 132 characters. Special models also supported vector graphics and the APL character set. Some manufacturers, such as HOB or Attachmate, built on IBM 3270 compatible terminals.
The programming of 3270 applications in assembly language was very complex. As a convenience served at the IMS Message Format Service, in the CICS Basic Mapping Support ( BMS ) and TSO / ISPF, the panel definitions. For creating graphics software Graphical Data Display Manager provides a corresponding programming interface.
Today, few are still in use terminals. However, there are still isolated areas of application in which the terminal is preferred to a PC. Most of today's remaining 3270 applications often use a terminal emulator on a PC. IBM itself there was to the IBM 3270 PC - an ordinary IBM PC XT with hardware to emulate a 3270, which included a special graphics card and a PC/3270-Tastatur. For example, on Windows Hummingbird Host Explorer, IBM Personal Communications exist, Attachmate Extra! or Reflection, INTRA -SYS All in One 3270 or 3270 or HOBLink Terminal Edition.
A Java-based solution offered by IBM itself: Host On -Demand ( HOD ). It consists of a Java applet that builds a 3270 meeting in a web browser. In addition, the printer emulation screen is possible.
For the home user who wants to, for example, to access a tn3270 service ( still common especially in American libraries ) emulates a mainframe or by Hercules, exists with Vista TN3270 an affordable solution. For X11 (on Unix -like operating systems ) there is x3270, which also still contains programs for scripts. zLinux supports 3270 terminals.
The transmission protocol was originally BTAM, VTAM later. Today TCP / IP is used. Further uses a special Telnet variant, tn3270, used.