IBM 5280 Distributed Data System - Index of

Because the keyboard/display lOB in each partition contains pointers into thekeyboard/display storage, the validity table, storage area, diacritic table, scan codetranslate table, and the Katakana translate table (if required) can be located anywherein keyboard/display storage as long as the tables that require alignment on a256-byte boundary are properly aligned. However, the refresh buffer, status linerefresh area, and display translate table for a particular keyboard must all be locatedin the same section of keyboard/display storage (section F, B, 7, or 3). The displaytranslate table must always begin at address xFOO, and the display control area mustbegin at address xEAO of the appropriate section of keyboard/display storage.REFRESH BUFFER AREAThe keyboard/display storage contains refresh buffers for each keyboard/displayunit. These buffers act as refresh areas for display characters. The refresh area forthe status line(s) is separated from the refresh area for the remainder of the screen.This separate area is in addition to the refresh area appropriate for a particularscreen size.When a keystroke is processed by the keyboard/display microprocessor, it is translatedfrom the keystroke scan code to EBCDIC code. The EBCDIC code is placedinto the current record buffer in main storage within the partition associated withthe keyboard, and translated to display code. The display code is then placed intothe refresh buffer in order to be displayed on the screen. The hexadecimal representationsof screen attributes are also placed into the refresh area.VALIDITY TABLEThe validity table defines:• The EBCDIC values used in the alphabetic only, numeric only, and Katakanaonly character sets.• The EBCDIC values of keys defined as diacritics.• The EBCD IC values that have to be translated to uppercase when the monocasefunction is enabled.• The scan codes of keys that are not typamatic.• The scan codes of keys that can be shifted from lowercase alphameric only if ashift key (not including the Shift Lock key) is simultaneously pressed, such asthe function keys to the left of the keyboard.Keyboard/Display Storage 123