What is
Indirect Addressing?
In
a computer that allows indirect addressing, the assembly language
programmer typically indicates an indirect address by adding a character such
as * to the absolute or symbolic address, or by enclosing it in parentheses.
A class
of ADDRESSING MODES supported by most processors in which an INSTRUCTION
contains not the address of its OPERAND, but the address of another location
that contains the address of the operand, called the ‘effective address’. In
REGISTER INDIRECT addressing it is a REGISTER that contains the effective
address. Indirect addresses are indicated in many ASSEMBLY LANGUAGES by writing
the operand in parentheses, for example: MOV B, (A) writes the contents of
register B to the location pointed to by the address in register A.
Indirect
addressing instructions may also include a PRE-INCREMENT or POST-INCREMENT (or
DECREMENT) feature that allows the operand address to be automatically
increased or decreased after each access; this simplifies ‘walking’ through the
items in an ARRAY.
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