Directives

Directives in SIC and SIC/XE are used to give information to the assembler and do not generate any instructions in the object code, but some may allocate memory. Book section indicates where in System Software: An Introduction to Systems Programming the directive is introduced.

Directive	Details	Book Section
START	Specifies the name (in label) and starting address for the program.	2.1
END	Indicates the end of the source program and (optionally) the first executable instruction.	2.1
CSECT	Begins a new control section. Label specifies the name.	2.3.5
EXTDEF	Operand is a comma-separated list of symbols declared in the current control section that other control sections can refer to.	2.3.5
EXTREF	Operand is a comma-seperated list of external symbols that the current control section uses.	2.3.5
BYTE	Generates a constant value, occupying as many bytes as needed.	2.1
WORD	Generates a one-word constant.	2.1
RESB	Reserves the indicated number of bytes.	2.1
RESW	Reserves the indicated number of bytes.	2.1
BASE
NOBASE
EQU	Stores a value in the symbol table.
ORG	Overrides the location counter when the assembler encounters this.
LTORG	Literal pool. All literal values placed before this directive are placed where it is located.
MACRO	Defines the start of a macro, used by macro processor.
MEND	Defines the end of a macro started by MACRO. Used by macro processor.
IF	Used by macro processor.
ELSE	Used by macro processor.
ENDIF	Used by macro processor.
WHILE	Used by macro processor.
ENDW	Used by macro processor.
SET
USE	Used for program blocks. The operand indicates the name of the program block.	2.3.4