standard and specialized tools. The specialized tools include solder and solderless
repair tools.
Become familiar with your computer’s publications and required
documentation before you jump into the computer’s hardware. This will enhance
your abilities as a technician. To perform this job effectively, you must understand
how a computer is organized internally. You must be able to recognize the
functional areas and what their capabilities are. You must understand how buses
function internally to transfer information internally.
The CPU is the computer’s brain. All the computational operations (logical
and arithmetic) and operational decisions are made in the CPU. The CPU controls
all computer operations.
The organization of the central processor becomes
increasingly more complex as you move from a relatively simple microprocessor
to a mainframe computer. But basically CPU functions are the same whether you
are talking about a mainframe, a minicomputer, or a microcomputer.
The CPU comprises two interacting sections: the control section and the
arithmetic logic unit (ALU). The control section directs the sequence of CPU
operations, interprets the instructions, and provides the timing and control signals
to carry out the instructions. The arithmetic logic unit implements arithmetic and/or
logical operations required by these instructions. The CPU generally consists of
timing circuits, registers, translators, selectors, comparators, adders, and
subtractors.
After completing this chapter, you should be able to:
Recognize the internal parts and functions of a computer
Describe how a control section of a CPU operates
Describe how the functions of the arithmetic logic unit (ALU) are
performed
Describe the types of buses and how they operate
TOPIC 1—CONTROL SECTION
Like a traffic director, the control section decides
when to start and stop (control and timing), what to do
(program instructions), where to keep information
(memory), and whom to communicate with (I/O). It
controls the flow of all data entering and leaving the
computer, from the beginning to the end of operations.
It does this by communicating or interfacing with the
ALU, memory, and I/O areas (fig. 5-2). It is also
capable of shutting down the computer when the power
supply detects abnormal conditions.
In some
computers it sends a signal to the control section to
initiate computer shut-down.
Specifically the control section manages the
operations of the CPU, be it a single chip
microprocessor or a full-size mainframe. The control
section of the CPU provides the computer with the
ability to function under program control. Depending
on the design of the computer, the CPU can also have
the capability to function under manual control through
man/machine interfacing. The man/machine interface
operating modes, the operations, and the functions,
along with the control section, will allow you to control
the operations and perform maintenance on the
computer(s).
NEETS Module 13, Introduction to
Number Systems and Logic Circuits, and chapter 4 of
this volume provide an excellent review of some of the
circuits used in the control section.
5-2
