Chapter 9 Writing Machine Language Instructions and Directive Statements
Writing Directive Statements 153
9.4 Writing Directive Statements
Directives differ from machine language instructions in that they only have effect on the assembler.
Directives specify program structure and start addresses, set constants and radices, and specify options
and label attributes.

List of directives

Below is a list of directives.
Document conventions
Symbols used in this chapter have the following meanings.
Directive Function
section Specifies a section
align Aligns the location counter value to a multiple of an expression.
end Indicates the end of the program.
listoff Stops list output from the line following this directive.
liston Starts list output from this directive.
notation Selects the coding format for numbers.
org Changes the program address.
opt Enables/disables optimization functions.
page Specifies the number of columns and rows on one page of the list file.
radix Selects the radix to be specified by default.
dc Stores an 8-bit constant in a memory area.
ds Reserves an 8-bit data area in a memory area.
dw Stores a 16-bit constant in a memory area.
dd Stores a 32-bit constant in a memory area.
equ Defines a name as the value of an operand expression.
global Declares external references with external declarations.
tit Specifies the header name of the list file.
xlistoff Stops list output including this directive.
xliston Starts list output from the line following this directive.
funcinfo Specifies additional information for a function.
assign Defines a name as the value of an operand expression.
[ ] Contents of brackets [ ] may be omitted.
( )... Contents of parentheses ( ) may be repeated.
| Specify one or the other of the terms delimited by a vertical bar |.