Lecture 1: Introduction to Computing Systems
Course Objectives:
q To motivate students about the exciting and fast
evolving world of computing.
q To introduce the fundamental principles and concepts
of computing.
q To survey important computer science concepts.
q To expose the students to one particular high-level
programming language, namely C and allow them master its syntax and semantics.
q To promote good communication skills among programmers
with emphasis on structured programming and documentation.
Major Areas of Computing
q Algorithms and data structures
q Programming languages
q Computer architecture
q Operating system
q Numeric and symbolic processing
q Databases
q Software engineering
q Artificial intelligence
q Data communications
q Human-computer interaction
Computer System: Main Components
A computer system is made up of
two main entities: hardware and software .
q Hardware: This is the physical entity of the computer
consisting of all the electronic and mechanical components of the computer.
The
hardware consists of three main components:
Ø Central Processing Unit
(CPU)
Ø Memory
Ø I/O Peripherals
q Software: This is the non-physical entity of the
computer which drives the hardware.
There
are two main kinds of software:
Ø System software
Ø Application software
I/O `Peripherals' Devices
q Computers normally require input data which they
process and eventually producing an output.
q How do we feed the input to the computer and how do we
get the produced output? --- I/O
devices
q There are many different media through which the
computer performs input and output. Some of these are:
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1.
Keyboard
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2.
Printer
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3.
Mouse
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4.
CDROM
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5.
Barcode scanner
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6.
Monitor
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7.
Speaker
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8.
Microphone
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9.
Diskettes
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q A major shortcoming of these I/O devices is that they
are generally slow compared to the high speed at which CPU processes
information.
Computer Memory
q Why is memory needed? Because the CPU can process
information much quicker than the I/O devices can supply it
q Information from the peripherals is put in memory until
all information for a particular program is available in the memory
q The CPU then processes the data and returns the
resulting information to the memory
q The memory is an electronic system which can therefore
supply the CPU with information at a suitably high rate
q The memory is used to store programs (instructions to
CPU) as well as data
q Only one access to the memory can be in progress at
any one time
The CPU: Basic Components/Functions
q Main components
Ø Control unit (CU)
Ø Arithmetic and logic unit (ALU)
Ø Registers
q Basic functions
Ø Data transfer-this is the
most important function taking about 95% of processor time
Ø Arithmetic and logic
operations
Ø Decision-making operations
The CPU
q This is the center piece of the whole computer system
which initiates all actions in the computer system.
q Uses registers to store, temporarily, a number of
words copied from memory. Why?
q The CPU has an instruction register and data
registers. Instructions forming a program are stored in adjacent locations in
memory. Program Counter (PC) is a special-purpose register which hold the
memory address of the next instruction to be fetched and executed by the CPU
q Registers are used to provide fast access to data by
the CPU. They, thus, help to increase the useful amount of work done by the CPU
and minimise CPU idle time