Addressing Modes
Most instructions allocate six bits to specify an operand. Three bits select one of eight addressing modes, and three bits select one of the eight general registers. The use of three-bit groups made octal notation natural.
In the following sections, each item includes an example of how the operand would be written in assembly language for a hypothetical single-operand instruction with symbol OPR. Rn means one of the registers, written R0 through R7. (Rn) signifies the contents of that register.
Read more about this topic: PDP-11 Architecture
Famous quotes containing the words addressing and/or modes:
“But what is quackery? It is commonly an attempt to cure the diseases of a man by addressing his body alone. There is need of a physician who shall minister to both soul and body at once, that is, to man. Now he falls between two stools.”
—Henry David Thoreau (1817–1862)
“I cannot beat off
Invincible modes of the sea, hearing:
Be a man my son by God.
He turned again
To the purring jet yellowing the murder story,
Deaf to the pathos circling in the air.”
—Allen Tate (1899–1979)