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:
“One year, I’d completely lost my bearings trying to follow potty training instruction from a psychiatric expert. I was stuck on step on, which stated without an atom of irony: “Before you begin, remove all stubbornness from the child.” . . . I knew it only could have been written by someone whose suit coat was still spotless at the end of the day, not someone who had any hands-on experience with an actual two-year-old.”
—Mary Kay Blakely (20th century)
“The Bostonians are really, as a race, far inferior in point of anything beyond mere intellect to any other set upon the continent of North America. They are decidedly the most servile imitators of the English it is possible to conceive.”
—Edgar Allan Poe (1809–1845)