Please forward this error screen to 158. Please forward this modern operating systems pdf for bsc it screen to 81. The 3270 series was designed to connect with mainframe computers, often at a remote location, using the technology then available in the early 1970s. Two of the major design goals of 3270s are minimizing the amount of data transmitted, and minimizing the frequency of interrupts to the mainframe.
A field attribute occupies a physical location on the screen that also determines the beginning and end of a field. Using a technique known as “read modified”, a single transmission back to the mainframe can contain the changes from any number of formatted fields that have been modified, but without sending any unmodified fields or static data. Some users familiar with character interrupt-driven terminal interfaces find this technique unusual. This is mainly used for debugging purposes to preserve the application program screen contents while replacing it, temporarily, with debugging information. Early 3270s offered three types of keyboards. 78 key version with twelve. PF keys and two PA keys.
Later 3270s had twenty-four PF keys and three PA keys. Application program functions such as termination, page-up, page-down, or help can be invoked by a single key press, thereby reducing the load on very busy processors. But end-user responsiveness was arguably more predictable with 3270, something users appreciated. 3279 screens did not meet with success because its programmers were not able to properly adapt the spreadsheet’s user interface to a “screen at a time” rather than “character at a time” device.
The modified data tag is well suited to converting formatted, structured punched card input onto the 3270 display device. With the appropriate programming, any batch program that uses formatted, structured card input can be layered onto a 3270 terminal. 3270 interaction because of its design understanding. With the arrival of the web, application development has in many ways returned to the 3270 approach.
In the 3270 era, all application functionality was provided centrally. PC and connected to the controller through a coaxial cable. IRMA also allows file transfers between the PC and the mainframe. MTS was the default OS at Michigan for many years, and was still used at Michigan well into the 1990s. The IBM 3270 display terminal subsystem consisted of displays, printers and controllers. Ethernet in addition to co-ax. They also supported attachment of asynchronous ASCII terminals, printers, and plotters alongside 3270 devices.