Post on 15-Nov-2014
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Computers Everywhere
Affect every aspect of our lives. Process the data which makes a modern
society function. Embedded in a huge range of devices. Microcomputers bring computing directly
to almost everyone. Opening up new ways of communication. Breaking down political and national
boundaries.
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Information Systems
A computer is part of an information system» Hardware» Software » Data » People» Procedures
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Hardware and Software
HardwareThe physical components associated with a computer or other system.» CPU» Peripheral Devices
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Hardware and Software
SoftwareThe programs which control the operation of a computer, together with the associated documentation. Divided into system and application software.A program is a set of instructions that tell the computer how to process data to produce the required results.
5Why Learn About Hardware and Software?
Hardware can improve productivity, increase revenue, reduce costs, and provide better service
Managers are expected to know about hardware» To help define business needs» To ask questions and evaluate options
when buying equipment
6Why Learn About Hardware and Software?
Software is indispensable for any computer system
Systems software needed for input, calculations, and output
Application software aids in productivity
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Computer Systems: Integrating the Power of Technology
Choosing the right computer hardware requires understanding its relationship to the information system and needs of the organization
Hardware objectives are subordinate to, but supportive of, the information system and the current and future needs of the organization
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Data and Information
What is data? Data is unorganised facts, numbers,
letters and symbols represented in a formalised manner suitable for communication, interpretation and processing by humans or computers.
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Data and Information
What is information? Information is data which has been
assigned a commonly understood meaning.
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Data and Information
Data:AB34652 22025 46723 45890 98345
Information:Number of Products Sold in November in All Sales Areas
Product South North East West
AB34652 22025 46723 45890 98345
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People
Those who use the information provided by the hardware and software. (end-users)
Those who supply the raw data for processing.
Those who write programs. (programmers)
Those who support the running of the system. (computing officers, support engineers)
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Procedures
The rules or guidelines for the running of the information system and its components.» System manuals» Program manuals
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What is a System?
A system is an organised set of related components established to perform a certain task.
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What is a Computer?
An electronic device that can perform the following tasks:» Respond predictably to input» Store the set of instructions needed to
process the input» Process the input according to these
instructions» Store the results of processing» Output information
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Computer Architecture
Hardware
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Architecture
Architecture is those attributes visible to the programmer» Instruction set » Number of bits used for data representation » I/O mechanisms » Addressing techniques» e.g. Is there a multiply instruction?
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Organization
Organization is how features are implemented» Control signals» Interfaces» Memory technology» e.g. Is there a hardware multiply unit or is it
done by repeated addition?
18Architecture & Organization
All Intel x86 family share the same basic architecture
The IBM System/370 family share the same basic architecture
This gives code compatibility» At least backwards
Organization differs between different versions
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Structure & Function
Structure is the way in which components relate to each other
Function is the Operation of individual components as part of the structure
All computer functions are:» Data processing» Data storage» Data movement» Control
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Setup of a Microcomputer
21Setup of a Microcomputer(contd.)
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Computer Operations
Input Processing Output
External Storage
23Von Neumann Architecture
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Instruction Execution
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Arithmetic Logical Unit
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Computer Organization
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Logical PC structure
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Structure - Top Level
Computer
Main Memory
InputOutput
SystemsInterconnection
Peripherals
Communicationlines
CentralProcessing Unit
Computer
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Structure - The CPU
Computer Arithmeticand Logic Unit
ControlUnit
Internal CPUInterconnection
Registers
CPU
I/O
Memory
SystemBus
CPU
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Hardware Components
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Hardware Components
Central processing unit (CPU)» Arithmetic/logic unit (ALU): performs calculations and
makes logical comparisons» Control unit: accesses, decodes and coordinates data
in CPU and other devices Primary memory: holds program instructions and
data for processing; Random Access Memory chips Secondary storage: long-term storage; magnetic disc
Input and output devices Communications devices
32Microcomputer Structure
Address
bus
ALU
Primary Memory
Input
Output
Secondary Memory
Control Unit
Data
bus
Control
busCPU
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Central Processing Unit
Highly complex electronic circuitry that converts data input to information output
Consist of two parts, control unit and arithmetic / logic unit (ALU)
Control unit interprets and executes a list of instructions which comprise the program
The list of operation that performs the desired task is called a program
34Central Processing Unit (CPU)
The microprocessor operates on a list of stored instructions which are executed in a sequential manner, so called a Stored Program Computer.
Arithmetic / Logic Unit executes arithmetic and logical operations.
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Primary Memory
High speed semiconductor memory used to store the program and also any data values which are associated with it
Directly addressed by the microprocessor and the two principal types are read-only memory (ROM) and read/write memory (RAM)
Also known as the immediate access store or main memory
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Primary Memory
ROM is used only for permanent programs and unchanging data storage
RAM (Random Access Memory) is used to stored programs and data that can change during the operation of the computer
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Secondary Memory
Mass-storage devices, such as disk drivers, are not directly addressable but have large storage capacities at a relatively low cost
The contents must be transferred to the primary memory before the processor can access the information
Also known as the backing store
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Input/Output (I/O) Unit
Contains the interface circuits needed to allow the I/O devices to properly communicate with the computer
Examples of input devices are keyboard, image scanner, mouse ...
Examples of output devices are printer, plotter, monitor ...
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The Bus System
Information is passed between the various units of a computer via a communication subsystem called a Bus.
In practice a microprocessor bus is divided into three groups of signals:
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The Data Bus
A set of wires along which data is transferred between units
Signals are bi-directional, since data can flow into or out of the microprocessor
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The Address Bus
A set of wires along which is sent the binary code (the address) that identifies the memory location to be used
Addresses can only be issued by the microprocessor, so it is uni-directional
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The Control Bus
A collection of special signals that coordinates the activities of the various units
Each type of microprocessor has its own particular set of signals
8-bit microprocessors have 8-bit data bus and usually have 16-bit address bus, which allows them to address 64 Kbytes (216) memory locations
43Internal Architecture of Microprocessor
Microprocessor Types Microprocessors are commonly
characterized by the number of bits they process in a single instruction, which is generally determined by the width of the data path, typically are 4-bit, 8-bit, 16-bit, 32-bit and 64 bit.
44Internal Architecture of Microprocessor
Another major distinction is between single-chip microcomputers (often call microcontrollers) which include a microprocessor, memory, and I/O on the same chip, and general-purpose microprocessors, which require external memory and I/O circuits.
45Internal Architecture of Microprocessor
The Microprocessor The microprocessor may be considered to
comprise the following: A number of registers (temporary storage
elements) which can each hold a number of bits of binary information, typically 8 bits (1 byte) and 16 bits representing program instruction, data, addresses.
Program counter (PC) or Instruction Pointer (IP), is used to hold the address of next instruction to be executed.
46Microprocessor Internal Architecture
Control Unit
Instruction Register
Accum
ulator
Flags General Purpose
Registers
Stack Pointer
Program Counter
Address Buffer
Data Buffer
Arithmetic / Logic
Unit
Control signals
Internal control signals
Address bus Data bus
47Microprocessor Internal Architecture
Instruction Register (IR) is used to hold an instruction whilst it is being decoded (by the instruction decoder) to determine the actions necessary to execute the instruction.
General-purpose registers are a set of specified memory locations within the microprocessor used for holding temporary values awaiting further processing.
48Microprocessor Internal Architecture
Accumulator is a special microprocessor register used to hold one of the operands and also the result of an arithmetic or logical operation.
Stack Pointer (SP) is a special microprocessor register pointing to a stack implemented in the primary memory
Arithmetic / Logic Unit (ALU) is the circuitry which performs arithmetic (+, -, x, / ... ) and logical (AND, OR, NOT, XOR, ...) operations.
49Microprocessor Internal Architecture
Timing and control unit is the circuitry which controls both the internal operation of the microprocessor (the operation of ALU and registers) and the external operation of the complete microcomputer system (memory and I/O read/write).
50Microprocessor Internal Architecture
Flags are single-bit information which indicate some particular aspect of the CPU operation result.
e.g. Z = result is zero, OV = result is overflow, C = carry or borrow is generated
in addition or subtraction operation