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PDP-11-BASED 6800 CROSS-ASSEMBLER DESCRIPTION SEMANTICS OF THE SYNTAX DESCRIPTION ::= MEANS DEFINED AS OR DESCRIBED TO BE ... MEANS ANY CHARACTERS OR VALUES BETWEEN <> ARE SEPARATORS AND NOT A PART OF THE ASSEMBLER ! MEANS OR , I. E. A!B MEANS EITHER A OR B () MEANS OPTIONAL [] MEANS APPEARS 0 OR MORE TIMES IN A ROW []N] MEANS APPEARS 0 TO N TIMES IN A ROW <HEXDIGIT> ::= "0"..."9" ! "A"..."F" <BYTE> ::= <HEXDIGIT><HEXDIGIT> <DBLEBYTE> ::= <BYTE><BYTE> <HEXNUM> ::= "$"[<HEXDIGIT>]4] <PGNUM> ::= "*" ! <HEXNUM> ("*" IS THE LABEL FOR THE PROGRAM COUNTER) <ALPHA> ::= "A"..."Z" <ALPHANUM> ::= <ALPHA> ! "0"..."9" <ASCIICHAR> ::= <ALPHANUM> !<ANY PRINTABLE CHAR EXCEPT "/"> <COMCHAR> ::= <ASCIICHAR> ! "/" <LABEL> ::= <ALPHA>[<ALPHANUM>]5] <SYMBOL> ::= <LABEL> ! "*" <SP> ::= " "(<SP>)!<'TAB'>(<SP>) <VALUE> ::= <SYMBOL>!<HEXNUM> <MODVALUE> ::= <VALUE>! "#"<VALUE> ! <VALUE>",""X" <ASCIISTR> ::= <ASCIICHAR>(<ASCIISTR>) <COMMENT> ::= <COMCHAR>(<COMMENT>) <OPERATOR> ::= <ALPHA><ALPHA><ALPHA> <REG> ::= "A" ! "B" <INSTR> ::= <OPERATOR>!<OPERATOR><SP><MODVALUE>! <OPERATOR><REG>!<OPERATOR><REG><SP><MODVALUE> <BYTEFIELD> ::= "$"<BYTE> [","("$")<BYTE>] <DBLEBYTEFIELD> ::= "$"<DBLEBYTE> [","("$")<DBLEBYTE>] FORMAT OF STATEMENTS <GOODLINE> ::= (<SP>)"*"<COMMENT> ! <ASSEMBDIRECTIVE> ! (<LABEL>)<SP><INSTR>(<SP><COMMENT>) ^NOTE THE SPACE BEFORE THE INSTR THERE MUST BE A SPACE IF NO LABEL. . LEGAL INSTRUCTION NAMES ARE FOUND IN THE INSTRUCTION CARDS. THE LEGAL ASSEMBLER DIRECTIVES AND THEIR MEANINGS ARE AS FOLLOWS. <SP>"ORG"<SP><HEXNUM> ;THIS ASSIGNS VALUE TO THE PROG CTR LIKE * = VALUE. <SYMBOL><SP>"EQU"<SP><PGNUM> ; MEANS SYMBOL = VALUE (<LABEL>)<SP>"FCB"<SP><BYTEFIELD> ;FORM CONSTANT BYTE,CAN HAVE A LABEL AND SEVERAL VALUES, INCLUDING NOTHING, WHICH COMES OUT A 0. THE DIRECTIVE EVALUATES THESE VALUES AND PUTS THE CORRESPONDING VALUES IN MEMORY. (<LABEL>)<SP>"FCC"<SP>"/"<ASCIISTR>"/" ;FORM CONSTANT CHARACTER, TRANSLATES STRINGS OF CHARACTERS TO THEIR 7-BIT EQUIVALENT. (<LABEL>)<SP>"FDB"<SP><DBLEBYTEFIELD> ;FORM DOUBLE BYTE, EACH VALUE BECOMES A DOUBLE BYTE IN MEMORY. (<LABEL>)<SP>"RMB"<SP><HEXNUM> ;RESERVE MEMORY BYTES, EFFECTIVELY *=*+VALUE, ADDS VALUE TO PROGRAM COUNTER. <SP>"END" ;SIGNALS THE END OF THE PROGRAM. MUST BE FOLLOWED BY MON DIRECTIVE, OR BY ANOTHER PROGRAM. <SP>"MON" ;SIGNALS THE END OF ALL PROGRAMS. "NAM"<SP><ASCIISTR> ;THIS NAMES THE PROGRAM AND IS PRINTED ON THE TOP OF EACH PAGE OF ASSEMBLY OUTPUT. "OPT"<SP><BYTE>"00" ;BYTE OF FORM "$JK" ;OPTIONS, IF <J> ="F", NO OBJECT TAPE IS CREATED. <K>="F", SYMBOL TABLE RETENTION THROUGH SUCCESSIVE ASSEMBLIES.