Computer System Chapter 3

Chapter Three: Computer System

• A computer system is a group of components working together to achieve a common objective
• A computer system is composed of hardware and software components
• Computer architecture is the science of selecting and interconnecting hardware components to accomplish functional, performance, and cost goals
• Computer hardware is the physical part of the computer system that can be touched
• A computer takes input, processes it according to instructions, and produces output
• The hardware of a computer system is a collection of interacting physical parts responsible for various operations
• The CPU (Central Processing Unit) is the "brain" of the computer, a VLSI chip plugged onto the motherboard controlling internal/external devices and performing arithmetic/logical operations
• The CPU operates on binary data (1s and 0s) representing electrical switches (ON/OFF)
• The CPU's functions include arithmetic operations (addition, multiplication, division) and logical operations (comparing values)

3.2.1 Central Processing Unit (CPU)

• The CPU is referred to as the brain of the computer system
• It is a VLSI chip plugged onto the motherboard
• It controls internal and external devices
• It performs arithmetic (addition, multiplication, division) and logical operations
• It is the most costly and main component of the computer system
• It operates on binary data (1s and 0s)
• It supervises and controls arithmetic and logic functions

3.2.1.1 The Control Unit

• The control unit manages and controls the flow of information within the computer system
• It fetches instructions from memory
• It translates instructions into computer functions and sends signals to other hardware components to perform those functions
• It determines the next instruction to be executed

3.2.1.2 The Arithmetic Logic Unit (ALU)

• The ALU is the "number cruncher" of the computer
• It performs arithmetic calculations (addition, subtraction, multiplication, division) and comparisons (e.g., is A greater than B?)
• It is responsible for executing instructions that involve mathematical or logical operations

3.2.1.3 Registers

• Registers are special high-speed memory units
• They store data, instructions, addresses, and intermediate calculation results that the CPU is currently working on
• Registers act as the CPU's working memory

3.2.1.4 CPU Characteristics

• Machine Cycle Time: measured in fractions of seconds (from milliseconds to picoseconds)
• Clock Speed: a series of electronic pulses at a predetermined rate that affects machine cycle time. Measured in Hertz (cycles per second), usually megahertz (MHz) or gigahertz (GHz)

3.2.1.5 World Length and Bus Line Width

• Data is moved in groups of bits (binary digits, 0 or 1)
• Word length refers to the number of bits the CPU can process at once — affects overall system performance
• The bus line width determines how many bits a bus line can transfer at once

3.2.2 Storage Units

• Storage units are used to store data
• Two main types: Primary and Secondary storage

3.2.2.1. Primary Storage

• Also called Main Memory
• Implemented by RAM and ROM technologies that store programs and data being actively used
• RAM: Volatile (data lost when power off) needed for active use
• ROM: Non-volatile (data retained when power off) stores permanent instructions
• RAM is further categorized into: Dynamic RAM (DRAM) and Static RAM (SRAM)
• DRAM uses a refresh circuitry; SRAM is faster but more expensive

3.2.2.1.2 Read-Only Memory (ROM)

• ROM is non-volatile, and data cannot be easily written to. There are various types, including Masked ROM, Programmable ROM (PROM), Erasable Programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), and Flash ROM

3.2.2.2 Secondary Storage

• Also called Auxiliary Storage
• Used to store data outside the main memory and for long-term storage
• Two main access methods: Sequential and Direct access.
• Sequential access method reads data by reading through all prior data until the targeted data is reached
• Direct access method retrieves data by accessing the data's specific location.
• Some examples are punched cards, magnetic tapes, magnetic disks (hard drives, floppy disks).

3.2.3 Input/Output (I/O) Units

• Allow data to be entered into or retrieved from the computer
• Input devices include keyboards, mice, scanners, and other devices
• Output devices include monitors, printers, and other peripherals

3.2.3.1 Input Unit

• Used to enter data into the computer for processing
• Converts human-readable data into a format the computer can understand
• Examples: Keyboard, disk drives, mouse

3.2.3.2 Output Unit

• Displays the results of computations or processes
• Converts computer-readable data into a format humans can understand
• Examples: Monitors, printers, speakers

3.3 Computer Software

• Software is a collection of instructions that enable the computer to perform tasks
• Classified into system software and application software
• System software manages computer hardware and provides a platform for application software

3.3.1 System Software

• Facilitates the computer's operation
• Organizes and manages machine resources. Handles input/output
• Controls the hardware
• Coordinates the activity between the user and the computer
• Examples are operating systems (handles tasks between the user and hardware)

3.3.1.A Operating System

• The master program of the computer
• Coordinates tasks between the user and the computer
• Manages resources and handles communications between components
• Has control programs and input/output management
• Real-time, multi-user, single tasking operating systems

3.3.2 Application Software

• Designed to solve specific tasks, like word processing, spreadsheets, database management

3.3.2.A Word Processors

• Used for text creation, editing, and formatting

3.3.2.B Spreadsheets

• Used for calculations, financial or mathematical analysis

3.3.2.C Database Management Systems

• Allow storing, retrieving, and updating data efficiently

3.2.4 The Bus System

• A communication path between different computer components
• Internal bus connects CPU components
• External bus connects CPU to memory and peripherals
• Bus speed crucial for efficiency

This quiz covers the fundamental concepts of computer systems as detailed in Chapter Three. Explore the components that make up a computer system, including hardware and software, and understand the role of the CPU. Test your knowledge on how these elements interact to achieve computing objectives.