IBM 5280 Distributed Data System - Index of

The following illustration shows how the system table is used to find a screenformat control string that is located within the partition. In the illustration, thescreen format labeled SFMT02 was the second screen control format set up ',,·/ith aseries of .SFMT control statements.Source: ENTR(SFMT02);Object:~CF 00 01 00Bytes 79 and 80 ofthe Keyboard/Display lOB~~. ~ (/ System Tablel~ t--------IScreen Format Control StringFF 1 __. ___ __System Table for Prompts and Constant InsertsThe system table for prompts and constant inserts is built by the assembler whenit processes .DC control statements with the parameter TVPE=PRMT. The addressof the system table for prompts and constant inserts that are located within thepartition is stored in the keyboard/display lOB at\ hex 70, relative to the start of thelOB. The address of the system table for global prompts and constant inserts isstored in the system control block at absolute address hex FE. The storage pagenumber where the system table is located is stored in the system control block athex FB. (It must be on the same storage page as the system table for global screenformat control strings.)The system table for prompts and constant inserts that are located within the partitionconsists of one 2-byte entry for each prompt or constant insert. The 2-byteentry contains the address, relative to the beginning of the partition, where theprompt or constant insert is located. The first entry in the system table alwayscontains 2 bytes of zeros. The address of the first prompt or constant insert is atindex 1 in the table.The system table for global prompts and constant inserts consists of one 2-byteentry for each global prompt and constant insert. The 2-byte entry contains theaddress, relative to the b..eginning of the storage page, where the prompt or constantinsert is located. The first entry contains 2 bytes of zeros. The first prompt orconstant insert is at index 1 in the table. During program execution, if the screenformat control string that referred to the prompt or constant insert is a globalscreen format control string (indicated by bit 9 of the object code ENTR command),the system table for global prompts and constant inserts is used.In a source program, a prompt is referred to in a .SFMTPMT control statement; aconstant insert is referred to in a .SFMTCNS control statement. The assemblerconverts the labels included in the control statements to system table indexes.During program execution, when a screen format control string refers to a promptor constant insert system table index; the system finds the address of the promptor constant insert in the system table at that index.98