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MICROCOMPUTER INSTRUMENTATION AND CONTROL 4

MICROCOMPUTER OPERATIONS

A microcomputer stores Recall the basic computer block diagram of Figure 4.l. The central
information on a tempo- processing unit (CPU) requests information from memory (or from an input
rary basis within the device) by generating the address for the data in memory. The address with all
CPU registers. Informa- its bits is stored in the CPU is a binary number in a temporary data latch type
tion is transferred memory called a register. The outputs of the register are sent at the same time
between the CPU regis- over multiple wires to the computer memory and peripherals.
ters and the memory or
Buses
input/output sections by
means of one or more As shown in Figure 4.2, the group of wires that carries the address is called
sets of multiple wires; the address bus. (The word bus refers to one or more wires that is a common
each set is called a bus. path to and from various components in the computer.) The address register
used in most microcomputers holds 32 bits; these bits enable the CPU to access
2 memory locations. In a microcomputer, each memory location usually
32
contains multiples of 8 bits of data. A group of 8 bits is called a byte and a group
of 16 bits is sometimes called a word.

Figure 4.2
Buses and Registers

FPO

UNDERSTANDING AUTOMOTIVE ELECTRONICS 103