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BASIC COMPUTER ARCHITECTURE
INPUT DEVICES PRESENTED BY:
OUTPUT DEVICES PRESENTED BY:
MEMOMY PRESENTED BY:
CPU PRESENTED BY:
Introduction
In this presentation, we’ll discuss various input, output, and CPU(central processing unit),memory designed to meet the various needs and lifestyles of people.
What Peripheral Devices Suit Your Needs?
Input Devices Output Devices Storage Devices
Input Devices
• Input device captures information and translates it into a form that can be processed and used by other parts of your computer. KeyboardsPointing devicesGame controllersScannersStylusesMicrophonesDigital camerasWeb cams
Input Devices
The keyboard is the most common input device. Types of keyboards include:• Wireless• Multimedia and one-touch access• Portable keyboards for PDAs
Types of Input Devices
Pointing Devices
Pointing devices are mainly used to choose and enter commands
Pointing devices tend to have PS/2 connectors or USB connectors• PS/2 connector fits into a PS/2 port, which a small round
socket with small holes that fit the pins on the connector• USB connectors fit into USB ports, and these are small
rectangular openings on the back or front of your computer, or even on your keyboard or monitor
Pointing Devices
Various pointing devices are available Types of pointing devices:
• MouseMechanical mouseOptical mouseWireless mouse
• Trackball• Touchpad• Pointing stick
Game Controller
Game controllers are used mainly to play games Types of gaming devices
• Gamepads• Joysticks• Gaming wheels• Force feed
Specialized Input Devices
Other types of input devices include:• Scanners• Styluses• Microphones• Digital cameras• Web cams
Scanner
•Scanner is a light sensitive device that helps you copy or capture images, photos, and artwork that exist on paper. Types of scanners include:Flatbed
Styluses
• Stylus is an input device consisting of a thin stick that uses pressure to enter information or to click and point
• Styluses are used with:PDAs Tablet PCsGraphics tablets
Microphones
• Microphones are used to input audio
• Three main types of microphones are:Desktop microphonesHeadsetsDirectional microphones
• Speech recognition is increasingly being included in application software
Digital Cameras
Digital cameras are used to: • Download images to a computer• Post pictures to the Web• Produce videos
Resolution is measured in megapixels Higher the resolution, better the
image quality, but the more expensive the camera
Web Cams
• Web cam is a video camera that can be used to take images for uploading to the Web
Output Devices
Output devices take information within your computer and present it to you in a form that you can understand
Main output devices: Monitors Printers Speakers
Flat Panel Display Devices
Devices with flat-panel displays• Tablet PCs
• PDAs
• Cellular phones
• Desktop computers
Monitors
CRTs Flat-panel displays
Gas plasma LCD (liquid crystal display)
Passive matrix Active matrix
Called TFT (thin film transistor) Separate transistor for every pixel
Printers
Inkjet – most popular Makes images by forcing droplets
through nozzles Top speed is 20 pages per minute
Laser Forms images using an
electrostatic process Prints between 3 and 30 pages per
minute
Printers - Cont
Resolution of a printer is the number of dots per inch (dpi) it produces.
Higher the resolution, better the image, and usually the more costly the printer
Printers - Cont.
Multifunction printer:• Scan, copy, fax, and print
• Can be either inkjet or laser
• Cost less than buying individual units
• Take up less desk space
Speakers
A speaker is a device that produces computer output as sound
Speakers are common devices in computer systems Examples include:• Built-in speaker• Two-device set speakers• Surround sound speakers
CPU: 3 Major Components
ALU (arithmetic logic unit) Performs calculations and comparisons (data changed)
CU (control unit): performs fetch/execute cycle Functions:
Moves data to and from CPU registers and other hardware components (no change in data)
Accesses program instructions and issues commands to the ALU
Subparts: Memory management unit: supervises fetching instructions
and data I/O Interface: sometimes combined with memory
management unit as Bust Interface Unit Registers
Example: Program counter (PC) or instruction pointer determines next instruction for execution
System Block Diagram
Concept of Registers
Small, permanent storage locations within the CPU used for a particular purpose
Manipulated directly by the Control Unit Wired for specific function Size in bits or bytes (not MB like memory) Can hold data, an address or an
instruction How many registers does the LMC have?
Registers Use of Registers
Scratchpad for currently executing program Holds data needed quickly or frequently
Stores information about status of CPU and currently executing program Address of next program instruction Signals from external devices
General Purpose Registers User-visible registers Hold intermediate results or data values, e.g.,
loop counters Equivalent to LMC’s calculator Typically several dozen in current CPUs
Special-Purpose Registers
Program Count Register (PC) Also called instruction pointer
Instruction Register (IR) Stores instruction fetched from memory
Memory Address Register (MAR) Memory Data Register (MDR) Status Registers
Status of CPU and currently executing program
Flags (one bit Boolean variable) to track condition like arithmetic carry and overflow, power failure, internal computer error
Register Operations Stores values from other locations
(registers and memory) Addition and subtraction Shift or rotate data Test contents for conditions such as zero
or positive
Operation of Memory
Each memory location has a unique address
Address from an instruction is copied to the MAR which finds the location in memory
CPU determines if it is a store or retrieval Transfer takes place between the MDR
and memory MDR is a two way register
©2003 The McGraw-Hill Companies
Relationship between MAR,
MDR and MemoryAddress
Data
MAR-MDR Example
Visual Analogy of Memory
Individual Memory Cell
Memory Capacity Determined by two factors
1. Number of bits in the MAR LMC = 100 (00 to 99) 2K where K = width of the register in bits
2. Size of the address portion of the instruction 4 bits allows 16 locations 8 bits allows 256 locations 32 bits allows 4,294,967,296 or 4 GB
Important for performance Insufficient memory can cause a processor
to work at 50% below performance
RAM: Random Access Memory
DRAM (Dynamic RAM) Most common, cheap Volatile: must be refreshed (recharged
with power) 1000’s of times each second SRAM (static RAM)
Faster than DRAM and more expensive than DRAM
Volatile Frequently small amount used in cache
memory for high-speed access used
ROM - Read Only Memory
Non-volatile memory to hold software that is not expected to change over the life of the system
Magnetic core memory EEPROM
Electrically Erasable Programmable ROM
Slower and less flexible than Flash ROM Flash ROM
Faster than disks but more expensive Uses
BIOS: initial boot instructions and diagnostics
Digital cameras
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