COSI 131a Lecture Notes - Lecture 1: Central Processing Unit
7 Sep 2019
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Document Summary
The cpu consists of an alu and control unit. The alu performs computations, while the control unit interprets program instructions. The alu consists of registers and function unit. Registers are storage units, while the function unit consists of arithmetic and logic units. Registers and units are connected through the bus (a set of wires). Registers are very fast, but its use of memory is very expensive on the processor. Usually there are 32 64 registers, and each register holds a word. A word is the data size used in computation, which is also the amount of data transferrable over the data bus at a given time. Gpr are set directly by software; the assembly language instruction. Status registers convey information about previous/current operations, and are set as a side effect of software. The function unit performs computation with data in registers. All of the data used in computation is stored in the gprs.
