Orthogonality in Practice
In many CISC computers, an instruction could access either registers or memory, usually in several different ways. This made the CISC machines easier to program, because rather than being required to remember thousands of individual instruction opcodes, an orthogonal instruction set allowed a programmer to instead remember just thirty to a hundred operation codes ("ADD", "SUBTRACT", "MULTIPLY", "DIVIDE", etc.) and a set of three to ten addressing modes ("FROM REGISTER 0", "FROM REGISTER 1", "FROM MEMORY", etc.). The DEC PDP-11 and Motorola 68000 computer architectures are examples of nearly orthogonal instruction sets, while the ARM11 and VAX are examples of CPUs with fully orthogonal instruction sets.
Read more about this topic: Orthogonal Instruction Set
Famous quotes containing the word practice:
“As an example of just how useless these philosophers are for any practice in life there is Socrates himself, the one and only wise man, according to the Delphic Oracle. Whenever he tried to do anything in public he had to break off amid general laughter. While he was philosophizing about clouds and ideas, measuring a flea’s foot and marveling at a midge’s humming, he learned nothing about the affairs of ordinary life.”
—Desiderius Erasmus (c. 1466–1536)