lOMoARcPSD|5498213
Computer Architecture complete lecture notes for diploma
students and all
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Downloaded by Peter Mwakalinga ()
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CHAPTER THREE: INSIDE THE COMPUTER
Chapter Objectives
At the end of the chapter the learner shall be able to;
Explain the functions of the different components of the processor such as the
control unit, arithmetic/logic unit(ALU) and the system clock
Explain the term form factor in relation to mother boards
Explain the different types of buses and their functions in a computer system
Internal components are contained in the System Unit. The system unit is the
unit that houses the processing unit (processor), memory, the input output
controllers and the buses. The system unit is often called the Central Processing
Unit.
The external components of a computer are called peripheral devices
which include input and output.
3.1 The Processor
The processor contains the control unit and the arithmetic/logic unit(ALU)
and the system clock.
The control unit coordinates and controls all the operations carried out by
the computer. The control unit operates by repeating three operations
which are:
Fetch – cause the next instruction to be fetched from memory;
Decode – translate the program instruction into commands that
the computer can process
Execute – cause the instruction to be
executed The arithmetic/logic unit(ALU) plays
two roles.
, lOMoARcPSD|5498213
Arithmetic operations – these operations are addition,
subtraction, multiplication and division..
Logical operations – it compares two data items to determine whether
the first one is smaller than, equal to or greater than the second item.
The system clock – generates a continuous sequence of clock pulses to step
the control unit through its operation.
Examples of modern processors:
Some modern Intel Core i3, i5 and i7 processor brands are split into desktop and
laptop (or mobile) processors. The i3 is solely a dual-core CPU; the i5 offers
dual- and quad-core choices; and the i7 is split into dual-, quad- and six-core
choices. Intel Core i3, i5 and i7 are 1.2 GHz to 3.33 GHz, 1.06 GHz to 3.6 GHz and
1.06 GHz to 3.46 GHz, respectively.
3.2 Clock speed
In order to synchronise the various steps carried out during the fetch-execute
cycle, all the processors have an internal clock which generates regularly
timed pulses. All the processor activities, such as fetching an instruction,
reading data into the memory register etc. must begin on a clock pulse,
although some activities take more than one clock pulse to complete. Typically
the clock pulse rate in 2000 is around 500 megahertz (million cycles per
second). The clock speed, therefore, is one of the factors which will influence
the speed at which instructions are executed; a 600MHZ processor will in
general operate faster than a 500MHz processor.
The main features which distinguish one processor from another and which
determine the performance of each are;
Clock speed
Word size
Bus size
Architecture
, lOMoARcPSD|5498213
3.3 Registers
In addition the CPU contains circuitry controlling the interpretation and
execution of instructions. Special storage locations called registers are
included
in this circuitry to hold information temporarily while it is being decoded or
manipulated. They are shown in the block diagram below.
The registers shown in the block diagram above, which represents a ‘typical’
computer, each have a specific purpose, which is described below.
Program counter (PC) holds the address of the next instruction to
be executed. It is also known as the sequence control register
(SCR) or the sequence register.
General purpose registers are used for performing arithmetic
functions. In some computers, there is only one general purpose
register, usually called an accumulator, which acts as the working
area.
Current instruction register (CIR) contains both the operator and
Computer Architecture complete lecture notes for diploma
students and all
StuDocu is not sponsored or endorsed by any college or university
Downloaded by Peter Mwakalinga ()
, lOMoARcPSD|5498213
CHAPTER THREE: INSIDE THE COMPUTER
Chapter Objectives
At the end of the chapter the learner shall be able to;
Explain the functions of the different components of the processor such as the
control unit, arithmetic/logic unit(ALU) and the system clock
Explain the term form factor in relation to mother boards
Explain the different types of buses and their functions in a computer system
Internal components are contained in the System Unit. The system unit is the
unit that houses the processing unit (processor), memory, the input output
controllers and the buses. The system unit is often called the Central Processing
Unit.
The external components of a computer are called peripheral devices
which include input and output.
3.1 The Processor
The processor contains the control unit and the arithmetic/logic unit(ALU)
and the system clock.
The control unit coordinates and controls all the operations carried out by
the computer. The control unit operates by repeating three operations
which are:
Fetch – cause the next instruction to be fetched from memory;
Decode – translate the program instruction into commands that
the computer can process
Execute – cause the instruction to be
executed The arithmetic/logic unit(ALU) plays
two roles.
, lOMoARcPSD|5498213
Arithmetic operations – these operations are addition,
subtraction, multiplication and division..
Logical operations – it compares two data items to determine whether
the first one is smaller than, equal to or greater than the second item.
The system clock – generates a continuous sequence of clock pulses to step
the control unit through its operation.
Examples of modern processors:
Some modern Intel Core i3, i5 and i7 processor brands are split into desktop and
laptop (or mobile) processors. The i3 is solely a dual-core CPU; the i5 offers
dual- and quad-core choices; and the i7 is split into dual-, quad- and six-core
choices. Intel Core i3, i5 and i7 are 1.2 GHz to 3.33 GHz, 1.06 GHz to 3.6 GHz and
1.06 GHz to 3.46 GHz, respectively.
3.2 Clock speed
In order to synchronise the various steps carried out during the fetch-execute
cycle, all the processors have an internal clock which generates regularly
timed pulses. All the processor activities, such as fetching an instruction,
reading data into the memory register etc. must begin on a clock pulse,
although some activities take more than one clock pulse to complete. Typically
the clock pulse rate in 2000 is around 500 megahertz (million cycles per
second). The clock speed, therefore, is one of the factors which will influence
the speed at which instructions are executed; a 600MHZ processor will in
general operate faster than a 500MHz processor.
The main features which distinguish one processor from another and which
determine the performance of each are;
Clock speed
Word size
Bus size
Architecture
, lOMoARcPSD|5498213
3.3 Registers
In addition the CPU contains circuitry controlling the interpretation and
execution of instructions. Special storage locations called registers are
included
in this circuitry to hold information temporarily while it is being decoded or
manipulated. They are shown in the block diagram below.
The registers shown in the block diagram above, which represents a ‘typical’
computer, each have a specific purpose, which is described below.
Program counter (PC) holds the address of the next instruction to
be executed. It is also known as the sequence control register
(SCR) or the sequence register.
General purpose registers are used for performing arithmetic
functions. In some computers, there is only one general purpose
register, usually called an accumulator, which acts as the working
area.
Current instruction register (CIR) contains both the operator and
