IBM 5280 Distributed Data System - Index of

Chapter 3. Keyboard/Display StorageThe keyboard/display storage provides control information and refresh buffers forprocessing keystrokes and for displaying characters on the display screen. Eachkeyboard/display unit uses a separate portion of keyboard/display storage. Thetotal size of the portion of keyboard/display storage used by each keyboard/displayunit depends on the size of the refresh buffer necessary for the keyboard/displayunit's screen.The keyboard/display storage is loaded during system IPL from the IPL diskette.The keyboard/display lOB in each partition contains the addresses of the keyboard/display storage areas used by that partition's keyboard/display unit.The following is a general description of the data areas and refresh buffer areas withinkeyboard/display storage. The addresses for each keyboard/display unit beginswith an x, which represents hex F, B, 7, and 3 for keyboard/display units 1 through4 respectively. For example, if all keyboard/display units have a screen size of 1920characters, the keyboard/display storage for unit 1 begins at hex F400, for unit 2at hex B400, for unit 3 at hex 7400, and tor unit 4 at nex 3400. There is alsoadditional storage in a fifth section, which starts at hex 0000 and which is sharedby the four units.On a dual unit, the two keyboards share the same keyboard/display storage section.The first keyboard (keyboard 0) uses the lower-numbered rows of the refreshbuffer, control register 0, cursor address register 0, and status line refresh buffer 1.The second keyboard (keyboard 1) uses the higher-numbered rows of the refreshbuffer, control register 1, cursor address register 1, and status line refresh buffer 2.The following illustration shows the format of keyboard/display storage as it isgenerated for IPL bv the system configuration program (SYSCON).Keyboard/Display Storage 121