6.1.9.33 Org Directive

The ORG directive changes the value of the location counter within the current psect. This means that the addresses set with ORG are relative to the base address of the psect, which is not determined until link time.

Note: The much-abused ORG directive does not move the location counter to the absolute address you specify. Only if the psect in which this directive is placed is absolute and overlaid will the location counter be moved to the specified address. To place objects at a particular address, place them in a psect of their own and link this at the required address using the linkers -P option (see 7.1.18 P: Position Psect). The ORG directive is not commonly required in programs.

The argument to ORG must be either an absolute value, or a value referencing the current psect. In either case, the current location counter is set to the value determined by the argument. It is not possible to move the location counter backward. For example:

ORG 100h

will move the location counter to the beginning of the current psect plus 100h. The actual location will not be known until link time.

In order to use the ORG directive to set the location counter to an absolute value, the directive must be used from within an absolute, overlaid psect. For example:

PSECT absdata,abs,ovrld
ORG 50h
;this is guaranteed to reside at address 50h