Computer architecture

A+ Guide to Managing and maintaining Your PC

Chapter 1 - Introducing Hardware

Hardware Needs Software to Work
   Hardware refers to the computers physical components
   Software refers to the instructions that direct hardware to accomplish a task.
   Computers use four basic functions to do tasks
      input
      processing
      output
      storage
   People must interact with computers in a language that the computer understands
   The language that it understands are basic on and off of electrical pulses
   In order to make it easier for humans, those on (1) and off(0) were converted to other number systems
      Binary - 0 and 1 at simplest
         Bit - binary Digit
         Byte - 8 bits = 1 byte or one character
         ASCII - standard where the 1s and 0s of a byte mean certain things.
         Hexadecimal notation (Hex) - Breaks the byte into two parts and uses a numbering system of base 16 (0,1,2,3,4,5,6,7,8,9,a,b,c,d,e,f)
PC Hardware Components
   All hardware whether inside or outside the case need three things to operate
      A method for the CPU to communicate with the device
      Software to instruct and control the device
      Electricity to power the device
   Hardware used for Input and Output
      Most hardware used for input/output exisist outside the case and communicate through ports
      Most ports are on back of computers, some have some of the ports on the front
      Common Devices
         Keyboard
         mouse
         monitor
         printer
   Hardware Inside the Computer Case
      Motherboard
         CPU
         Memory
         other components
      Floppy drive, hard drive and CD ROM for permanent storage
      Power Supply with cords for providing electricity to components
      Circuit boards used by CPU to communicate with internal and external devices
      Cables to connect devices to circuit board and motherboard
   The MotherBoard
      Also called main system board
      Components found on all motherboards
         For Processing
            Central Processing Unit (CPU)
            Chips that support the CPU by controlling many motherboard activities
         For Temporary Storage - Random Access Memory (RAM)
         For communicating with other devices
            traces or wires on the motherboard
            expansion slots to connect expansion cards to the motherboard
            system clock to keep everything in sync
         Electrical system - power supply
         Programming and setup data
            Flash ROM - stores permanent instructions for basic hardware functions
            CMOS - configuration data
   The CPU and Chip Set
      CPU is chip in computer that does processing
      It is assisted by a chip set made for it to help control input and output to and from it
      IBM compatibles computers use: Intel, AMD, VIA, SiS, Cyrix
      Apple computers use chips from Motorola
   Storage Devices
      Primary Storage
         RAM - Random Access Memory
            Many styles
               SIMM - Single Inline Memory Modules
               DIMM - Dual Inline Memory Modules
               RIMM - Memory modules manufactured by Rambus
            These types of memory are volatile - loose what is in them when power is lost
            There is a type of memory called ROM (Read Only Memory)
            In Windows 9x and 2000 you can see CPU and memory installed
               Right click my computer on desktop and trace to properties
               Choose the general tab
               Read the information
      Secondary Storage
         Hard Drive
            Sealed case with platters that rotate to store information on.
            Most use EIDE (Enhanced Itegraded Drive Electronics) a growth from the IDE drives
            Four hard drives in a system is maximum if using IDE
            Motherboard usually has two connectors to accommodate the IDE drives (2 drivers per a connector)
            Drives receive power from power supply.
         Floppy Drive
            Two most common sizes are 3 1/2" and 5 1/4" with 3 1/2" most prevalent
            Due to CD-ROM and Zip drives, not as common as they used to be.
   Motherboard Components used for Communicating Among Devices
      Lines on the motherboard are referred to as traces
      when a group of them are together and use a protocol (a set of rules to communicate) then it is used to move data - a data bus
      Information does not travel down them as we visualize, but voltages are turned on and off in an agreed upon time frame.
      Width of data bus is the data path size
      Main Bus goes by several names: system bus, memory bus, hos bus, front side bus, external bus
      One line is used as system clock
         Receives timing information from a crystal on the motherboard
         Keeps all the components in sync
         Clock is measured in hertz (Hz) but more often in megahertz (MHz) and Gigahertz (GHz)
      Some traces go to expansion slots
         PCI (Peripheral Component Interconnect - used for high speed I/O devices)
         AGP (Accelerated Graphics Port -- used for video)
         ISA (Industry Standard Architecture - older, slower devices)
   Interface (Expansion) Cards
      See names as explained above
      easiest way to tell what they do is to look at the back of the card and see what type of port is on it.
   The Electrical System
      Power supply converts voltages that the computer needs to use from 110-120 colts AC power
      Also has a fan to cool the internal components
      Cables provide the power that is needed to the system
   Instructions and Data Stored on the Motherboard
      Basic instructions to start up the computer are stored in a special ROM, by special switches, and by using CMOS configuration
      Distinction between hardware and software softens with ROM chips
         ROM Chips contain software to boot up system
         They are permanent part of system so they are hardware
         Term for the hybrid is Firmware
      Some chips are BIOS - Basic Input /Output System
      Some ROMs can be upgraded, they are called flash ROM
      CMOS is another type of memory on motherboard used to start it up, contains small amount of memory
      Some installation information is stored with DIP switches or jumpers.