CS 08 Chapter 4 Hardware

Refers to the physical components of a computer

• CPU

• System unit and motherboard

• Storage devices

• Input devices

• Output devices

• Communication devices

CPU (Central Processing Unit)

• Brain of the computer

• Housed on the motherboard in the system unit

• Processes commands (from software)

• Controls function performed by other components

• Two main parts 

• Control unit - executes instructions 

• Arithmetic logic unit (ALU) - performs calculations

• Arithmetic calculations (addition, subtraction, etc)

• Logical calculations (comparisons)

Instruction Cycle

Sequence a CPU  (Control Unit) goes through to execute a command:

• Fetch - retrieves instruction from RAM/cache

• Decode - determines what the instructions is

• Execute - performs commands (data often fetched from RAM/cache)

• Store - store any result to RAM

Repeat for the next command, then the next, etc.

CPU Performance

Clock speed: the speed at which a processor executes the instruction cycle

• Gigahertz (GHz)- 1 billion cycles per second

• Megahertz (MHz) - 1 million cycles per second

Multiple Processors: Multi-Core Processors

• Two or more processors integrated on a single chip

• Increases processing speed over a single-core processor 

• Reduces energy consumption over multiple separate processors

• Dual-core (2 processors) and quad - core (4 processors) are common on personal computers

Multiple Processors: GPU (Graphics Processing Unit)

• Reduces the processing required of the system CPU for graphics-intensive processes

• Found on a video card

Parallel Processing

• Distributes processing across multiple processors

• Typically, each process (program) is assigned to a processor by the Operating System

• Can be simulated: hyper-threading

  • Intel processors

  • Single CPU appears as two logical processors

Pipelining

• Used to improve the performance of a single processor

• Similar to an assembly line in a factory

• Allows a single processor to process up to 4 instructions at the same time

  • After instruction 1 is moved from the fetch stage to the decode stage, instruction 2 is fetched, and so on

Cooling Systems

• Electronic components, especially processors, generate heat

• They need to be kept cool to prevent them from burning out

• Heat sink - metal used to draw heat away from the CPU

• Liquid cooling system

• Cooling fans (desktops only)

• USB-powered cooling pad for notebooks

System Unit / Motherboard

• System Unit - case that encloses and protects a computer’s internal components

• Motherboard - main circuit board of a computer; provides a way for devices to connect to a computer

  • CPU

  • Ports - used to connect peripheral devices directly

  • Expansion slots - plug in expansion cards into them (desktops only)

  • BIOS - instructions for booting the computer

  • Drive controllers - for connecting internal hard drives

  • Memory - chips for temporary storage

  • Data buses - wires that allow information flow

Ports

• Used to connect peripheral devices to the motherboard

Ports: USB

•  most common type of port, can connect many types of devices (such as printers, mice, keyboards, digital cameras, mobile devices, and external drives)

  • Can connect up to 127 devices to a single port (USB hubs)

  • Can provide power to devices

  • Hot-swappable - devices can be plugged and unplugged without turning off computer

  • Current version: USB 3.2 using USB-C connectors

Ports: Thunderbolt

• Can connect many types of peripheral devices

• Thunderbolt 2 is the standard on most Apple computers

• About the same speed as USB 3.2 (USB-C ports)

• Can connect up to six devices using one port

• Hot-swappable

Ports: Bluetooth

• Short-range wireless technology used to connect many types of peripheral devices

• Devices need to be paired

Ports: Firewire

• Legacy port (not found in newer computers)

• Can connect up to 63 devices to a single port, hot-swappable

• Mostly used for digital cameras

Ports: Other ports

Ethernet (network), audio, video (HDMI, DVI, etc.)

BIOS (Basic Input/Output System)

A program stored on a chip on the motherboard

Used to boot the computer (i.e. load the operating system when computer is turned on)

• BIOS chip is ROM (Read-Only Memory), i.e. non-volatile

  • May use flash memory, which can be electrically erased and reprogrammed

• Uses settings stored in a CMOS chip, which uses a battery to keep data from being erased when computer turned off

• Some modern computers use UEFI instead of BIOS

  • Settings can be stored on a chip, hard disk, or loaded over a network

Random Access Memory (RAM)

• Temporary (i.e. volatile) storage used by a computer to hold instructions and data while they are in use

• Also known as main memory (or sometimes just memory, though that can be a little confusing)

• Allows CPU to access much more quickly than from storage devices

• Memory boards - small circuit boards that contain memory chips

  • Easy to add memory to desktops - memory cards plug into slots on motherboard

Cache Memory

• CPU fetches instructions and data from RAM and stores results to RAM during the Instruction Cycle

• CPU is much faster than RAM, meaning it wastes lots of time waiting

• To improve performance, most computers use cache memory

  • Very fast memory that holds some instructions and data copied from the RAM

  • When CPU needs to fetch an instruction or data, the cache is checked first, and if it is there, it can be returned to the CPU more quickly

  • Operating systems predict which instructions and data CPU will need and copies them from the RAM to the cache

  • Cache memory capacity is normally very small (compared to RAM)

  • Why? It is very expensive

Different levels cache memory

• Different levels

  • L1 (level 1) - fastest and most expensive, built into CPU chip (256KB - 2MB)

  • L2 (level 2) - a little slower and less expensive, on a separate chip on motherboard (256KB - 8MB)

  • L3 (Level 3) - slowest and cheapest, but still faster than RAM (4MB - 256MB or more)

Storage Devices

• Stores instructions and data when they are not being used

• Contents not lost when power turned off (i.e. non-volatile)

• Compared to RAM:

  • Non-volatile (vs. volatile)

  • Much larger capacity (usually)

  • Much less expensive (per byte)

  • Much slower to access

Hard Drive (aka Hard Disk)

• The primary mass-storage device in most computers

• The primary hard drive holds the operating system (and usually other programs and data files)

• Most inexpensive type of storage device (4 TB for about $90)

• Can have very large capacities (12+ TB)

• Data stored magnetically on metal platters

• Can have a “hard drive crash” and lose all data

• Can be internal or external

Flash Memory (Storage)

• A non-volatile form of memory that can be electrically erased and programmed

• Has no moving parts

• Very reliable and fast

Flash Memory (Storage): Solid-State Drives (SSDs)

• Can be used in desktop and notebook computers instead of regular hard drive

• Much more expensive (than hard drives)

• More reliable, faster to access

• Usually smaller capacities

• Used as internal storage in many mobile devices

Flash Drives (portable storage)

• Also known as USB drives, key drives, thumb drives, or jump drives

• Small, portable solid-state drives

• Can connect to a computer via a USB port (USB flash drive)

• Average sizes are 16 GB - 64 GB, but can be smaller or larger

Memory Cards (portable storage)

• Used to expand the storage of smartphones, digital cameras, and other devices

• Various types (SD, micro SD, CF, etc.)

Optical Discs

• A laser beam is used to read data

  • CDs (about 700 MB)

  • DVDs (about 8.5 GB)

  • Blu-ray discs (about 100 GB)

• Can be read-only (ROM), recordable, or rewritable

• Has become largely legacy technology

Input Devices

• Used to enter data into a computer system

Input Devices Keyboard

• Keyboard

  • Most commonly used input device

  • 2 major issues:

    • Slow

    • Error-prone

  • QWERTY layout most common (designed to be slow)

  • Dvorak layout more efficient but not widely used

  • Ergonomic keyboards

Pointing Devices - moves a cursor on the computer screen (on a GUI)

• Mouse (most common pointing device)

• Touchpad (portables)

• Touchscreens (stylus)

Optical Scanners

• Flatbed scanners - scans a page (or pages) and saves as an image

• Barcode scanners (UPC - Universal Product Code)

• QR code scanners

RFID (radio-frequency identification) Scanners

Magnetic Strip Reader (credit cards, id cards, etc.)

NFC (Near Field Communication) Technology

• Allows two devices to share data with each other by touching them or bringing them close together

• Point of sale systems

• Biometric Scanners (fingerprints, retinas)

• Web cams

• Microphones

• Game controllers

Output Devices

• Monitors (aka displays)

• Work by lighting up pixels (picture elements) on the screen

• Three colors (Red/Green/Blue) used to create all colors

Resolution

• The number of horizontal pixels by vertical pixels, such as 1280×1024

• The higher the resolution, the sharper the image (but also smaller)

CRT (Cathode Ray Tube) Monitors

• Big, bulky, heavy

• Legacy technology

LCD (Liquid Crystal Display) Monitors

• Thinner, lighter

• Originally developed for portable computers

Projectors

• Produce larger output than a monitor

• Used in presentations (such as in-class lectures)

Video Cards

• Provides the data signal and connection for a monitor or projector

• Can have its own memory (VRAM)

• Can have a GPU

• VGA, DVI, HDMI

• They go with…

• Speakers and Headphones

• Sound Cards

Ink Jet Printers

• Most popular type of personal printer

• Sprays droplets of liquid ink onto paper

• For color printing, standard colors are cyan, magenta, yellow, and key (black), abbreviated as CMYK

• Cannot print very fast

• Printers very inexpensive, but ink cartridges have to be replaced often, so cost per page can be expensive

Laser Printers

• Most common type of business printer

• Uses a powdered ink cartridge (toner) that lasts about twice as long as liquid ink cartridges

• Laser printers more expensive than ink jet printers, but over time cost per page is less

• Print faster than ink jet printers

Dye-Sublimation Printers

High-end printers, mainly used for printing photographs

Photo Printers

Can be high-end ink jet or dye-sublimation printers

Thermal Printers

• Applies heat to specially coated heat-sensitive paper to produce output

• Mainly used to print receipts

• Output can fade over time

Three-Dimensional Printers

• Can create objects such as prototypes and models

• Dental and medical imaging, architecture, etc.

Plotters

Used to print very large output (blueprints, posters, maps)

Multifunction Devices

• A printer with a built-in scanner and sometimes fax capabilities

• Can be used as a copier

Adaptive Technology

• Used by individuals with disabilities to interact with technology

• Spurred by the Americans with Disabilities Act (ADA)

Adaptive Input Devices

• Braille-writing devices, eye-driven keyboards, onscreen keyboards, etc.

• Voice (speech) recognition - very difficult, requires lots of processing power, but commonly used on Internet-enabled devices today

Adaptive Output Devices

Magnifying the screen, speech synthesis, closed captions, Braille computer display, etc.

Communication Devices

Enables a device to connect to other devices on a network

Communication Devices: Network Adapters / Network Interface Cards (NICs)

Can be wired (uses Ethernet cables) and/or wireless (wifi)

Communication Devices: Analog Modems

• Used for dial-up Internet access (uses traditional phone lines)

• Very slow by today’s standards (max speed is 56,000 bits per second)

Communication Devices: Cable / DSL Modems

Use for high-speed Internet access

Communication Devices: Fax Machines

Sends and receives images over traditional phone lines