Английский для пользователей компьютеров. Ч.1. Белобородова М.Л - 25 стр.

hardware component is the central processing unit (CPU), which comprises
the control unit and the arithmetic/logic unit (ALU). CPUs used to be made
of vacuum tubes, magnetic cores, and transistors, which were all relatively
expensive, slow, and unreliable by today's standards. Today CPUs are
manufactured from silicon; one wafer from a silicon ingot can hold
hundreds of chips, called microprocessors. The electric circuitry that
forms the CPU is etched onto the surface of the chip.
The control unit of the CPU is responsible for directing and coordinating most of
the computer system activities. It uses machine language to run the show.
Unfortunately, the binary codes that make up machine language differ among
machines, which creates a problem of incompatibility.
The arithmetic/logic unit (ALU) performs all arithmetic and logical (comparison)
functions (plus, minus, times, divide by, equal to, less than, greater than, not
equal to).
Registers are special temporary storage locations within the CPU that very
quickly accept, store, and transfer data and instructions that are being used
immediately. The number and types of registers in a computer vary according to
the computer's design
To get data and instructions moving among the various components of the
system, the computer needs buses. The wider the bus, the more data it can carry at
one time.
The cycle that the computer goes through to fetch and execute one instruction is
called the machine cycle. In the instruction cycle part of the machine cycle, an
instruction is retrieved from main memory and is decoded in the CPU. The time it
takes to do this is called I-time. In the execution cycle, the instruction is executed
and the result is stored. The time this takes is E-time. An internal clock in the
CPU sets the speed of the machine cycle, which is measured in MHz—
megahertz, or millions of cycles per second.
A computer system could not operate without main memory, also called internal
memory, primary memory, primary storage, random access memory (RAM), or
simply memory. In general, main memory is used to store a copy of the main
software program that controls the general operation of the computer; to store a
copy of the business application software you are using; to temporarily store
data that has been input from the keyboard or other storage device until it is ready
for processing; and to temporarily store data that has been produced as a result of
processing until it is ready for output or secondary storage. In a microcomputer,
main memory, or RAM, chips are usually found in banks of nine on the