Instruction Set
The PDP-11 operates on bytes and words. Bytes are specified by a register number—identifying the register's low-order byte—or by a memory location. Words are specified by a register number or by the memory location of the low-order byte, which must be an even number. In most instructions that take operands, bit 15 is set to specify byte addressing, or clear to specify word addressing. In the lists in the following two sections, the assembly-language programmer appended B to the instruction symbol to specify a byte operation; for example, MOV became MOVB.
Read more about this topic: PDP-11 Architecture
Famous quotes containing the words instruction and/or set:
“Everything from airplanes to kitchen blenders—and even chopsticks—comes with an instruction manual. Children, despite all their complexity, do not.”
—Lawrence Kutner (20th century)
“If we cannot find a way to interpret the utterances and other behaviour of a creature as revealing a set of beliefs largely consistent and true by our own standards, we have no reason to count that creature as rational, as having beliefs, or as saying anything.”
—Donald Davidson (b. 1917)