2.2 The IBM 7171 ASCII Device Attachment Control Unit - Index of

4.6.2 Terminal Definition Tables, TDTs:Symbol Definitions for Pseudo Definition LanguageThis is a description of the TDTs which reside in NV -RAM. The description willbe useful for users that intend to create their own tool for TDT generation, or usersthat need to understand the TDT data structure. The description uses a Pascal likepseudo language which is defined in the next section. The description is presentedas an aid in generating TDTs. The pseudo definition language description is furtherdeveloped by several block diagrams on the following pages. The definitionsproceed in a top down fashion for both the pseudo definitions and the block diagrams.@ - a pointer to the data item described which implies a one word address- denotes allocation of memory, byte, character, word, or pointer- implies a sequence, i.e. 1, 2, 3, ..- a statement separator,- equivalence, same as an assembler equateI - the select indicator, chose from the items on either sideX - Hex Constant Prefix, i.e. X' 6B '- Constant delimiter, open and close string, i.e. 'a'/ / - Concatenation operator, i.e. 'a'/ /'b' = 'ab'Key Words and Their Meanings for the Pseudo Definition LanguageVariable Naming ConventionsARRAY- A sequence of data objects not different from eachotherRECORD- An Aggregate of different related data objectsEND- Terminator for the RECORD Key wordBYTE- a Unit of storage consisting of 8 bitsWORD- a Unit of storage consisting of 2 bytesASCII CHARACTER - a Unit of storage consisting of 8 bits, in the rangeX' 00' .. X' 7F'PTR indicates the variable is a word which contains an address. The variablenames in the type definitions are consistent with the TDT structures described inthis manual. To get a complete understanding of each variable name, the user mayneed to refer back to different sections.TypeTERMINAL HEADER IS RECORDSTATUS FLAG 1STATUS FLAG2PTR_PARSE_TABLEPTR_1ST_CSS_PTRCURSOR BASEPTR-TO-HOST-TRANSLATE TABLE ADDRESS-PTR_TO_TERM_TRANSLATE_TABLEPTR_TO_RESET_STRINGDELAYPTR-TO-SET GRPK RENDITION STRING- - -DEFAULT_PHYS I CAL_ROWSBYTE;BYTE;@PARSE_TABLE TYPE;@CSS_PTR_REC;WORD;@HOST_TRANSLATE_TABLEi@TERM_TRANS_TABLE;@RESET_STRING;WORD;@SGR;BYTE;Chapter 4. Customizing IBM 7171 Tables 4-51