export_week 12 chapter 10 peripherals Flashcards
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what are Peripherals?
Devices that are separate from the
basic computer
▪ Not the CPU, memory, or power supply
▪ Classified as input, output, and storage
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how Peripherals connected ?
▪ Connect via
▪ Ports
▪ Interface to systems bus
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types of storage Devices ?
▪ Primary memory
▪ Secondary storage
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what are the Secondary storage include?
▪ Data and programs must be copied to primary memory for CPU access
▪ Permanence of data - nonvolatile
▪ Direct access storage devices (DASDs)
▪ Online storage
▪ Offline storage – loaded when needed
▪ Network file storage
• File servers, web servers, database servers
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how is the speed measured in storage devices ?
Measured by access time and data
transfer rate
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Access time:
average time it takes a
computer to locate data and read it
▪ millisecond = one-thousandth of a second
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Data transfer rate:
amount of data that
moves per second
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Storage Hierarchy Diagram ?
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what are the Secondary Storage Devices
- Solid state memory
- Magnetic disks
- Optical disk storage
- Magnetic tape
- Network storage
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Characteristics of Secondary Storage Devices?
▪ Rotation vs. Linear
▪ Direct access vs. Sequential access
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what is falsh memory ?
▪ Nonvolatile electronic integrated circuit memory
▪ Similar to other read-only memory but uses a
different technology
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what does Flash memory permit ?
▪ Permits reading and writing individual bytes or small
blocks of data
▪ Small size makes it useful in portable devices such
as USB “thumb drives”, digital cameras, cell phones,
music players
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what is the Flash Memory immune to ?
▪ Relatively immune to physical shocks
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what is limitations of using Flash memory?
▪ Generates little heat or noise
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Disk Layouts – CAV vs. CLV
▪ CAV – Constant Angular Velocity
▪ Number of bits on each track is the same! Denser
towards the center.
▪ Spins the same speed for every track
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Disk Layouts – CAV vs. CLV
▪ CLV – Constant Linear Velocity
▪ All tracks have the same physical length and
number of bits
▪ Constant speed reading data off a track
▪ Drive has to speed up when accessing close to
the center of the drive and slow down when
accessing towards the edge of the drive
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Disk Layout – Multiple Zone Multiple zone recording
▪ Multiple zone recording
▪ Also known as zone bit recording (ZBR) or zone-
CAV recording (Z-CAV)
▪ Compromise between CAV and CLV
▪ Disk divided into zones
▪ Cylinders in different zones have a different
number of sectors
▪ Number of sectors in a particular zone is constant
▪ Data is buffered so the data rate to the I/O
interface is constant
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Multiple-Zone Disk
Configuration
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types of the Magnetic Disks
- Track – circle
- Cylinder – same track on all platters
- Block – small arc of a track
- Sector – pie-shaped part of a platter
- Head – reads data off the disk as disk rotates at high speed (4200-14000 RPM)
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A Hard Disk Layout
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A Hard Disk Layout
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Average seek time: ? how to Locate a Block of Data
time requied to move from one track
to another
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Latency:
time required for disk to
rotate to beginning of correct
sector
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Transfer time:
time required to
transfer a block of data to the
disk controller buffer
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Average Seek time
average time to move from one track to another
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Average Latency time
▪ average time to rotate to the beginning of the
sector
▪ Average Latency time = 1⁄2 * 1/rotational speed
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Transfer time
1/(# of sectors * rotational speed)
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Total Time to access a disk block
Avg. seek time + avg. latency time + avg. transfer time
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Magnetic Disks
▪ Data Block Format?
▪ Interblock gap
▪ Header
▪ Data▪ Interblock gap
▪ Header
▪ Data
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how ▪ Formatting disk ?
▪ Establishes the track positions, blocks and headers needed before use of the disk
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Disk Block Formats
Single Data Block
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Header for Windows disk
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what is Disk Arrays?
Grouping of multiple disks together
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RAID
Redundant Array of Inexpensive
Disks
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types of RAID>
▪ Mirrored array
▪ Striped array
▪ RAID 0 to RAID 5
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RAID – Mirrored is ?
▪ Pair of disks contain the exact same stores of data
▪ Reading data – alternate blocks of data are read from
hard drives and combined
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how is acess time is reduced inRAID – Mirrored ?
Access time is reduced by approximately a factor
equal to the number of disk drives in array
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what is Read failure RAID mirrored ?
block is marked and then read from
the mirrored drive
When using three or more mirrored drives, majority logic is used in the event of a failure. Fault-tolerant computers use this technique.
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what is the raid striped ?
▪ A file segment is stored divided into blocks on
different disks
▪ Minimum of three drives needed because one
disk drive is reserved for error checking
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writers in RAID - Striped is ?
block of parity words from each block of data is created and put on the reserved error checking disk
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what is the readers RAID - Striped?
parity data is used to check original
data
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what does RAID levels ?
▪ RAID 0 – not true RAID, no error checking or
redundancy, but data is placed across all
drives for increased speed
▪ RAID 1 – mirrored array
▪ RAID 2, 3, 4 – arrays that are striped in
different ways
▪ RAID 5 – error checking blocks are spread
across all drives
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how Optical Storage ?
Reflected light off a mirrored or pitted surface
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CD rom for the optical storage ?
CD-ROM
▪ 650 MB of data, approximately 550 MB after
formatting and error checking
▪ Spiral 3 miles long, containing 15 billion bits!
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what does CLV for optical storage do ?
▪ CLV – all blocks are same physical length
▪ Block – 2352 bytes
2k of data (2048 bytes)
16 bytes for header (12 start, 4 id)
288 bytes for advanced error control
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DVD – similar technology to CD-ROM
DID you know
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WORM
write-once read-many
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Optical Storage
types ?
▪ Laser strikes land: light reflected into detector
▪ Laser strikes a pit: light scattered
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Layout: CD-ROM vs. Standard Disk
CD-ROM
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Layout: CD-ROM vs. Standard Disk
Hard Disk
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Types of Optical Storage
WORM Disks
Medium-powered laser blister technology also used
for
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Medium-powered laser blister technology also used
for what ?
▪ CD-R, DVD-R, DVD-R, DVD+R
▪ CD-RW, DVD-RW, DVD+RW, DVD-RAM, DVD+RAMBD-RE
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what are the issues for Types of Optical Storage
▪ File compatibility issues between the different CD,
DVD and WORM formats
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talk about magnetic tape ?
- Offline storage
- Archival purposes
- Disaster recovery
- Tape Cartridges
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what are Tape Cartridges
▪ Linear tape open format vs. helical scan tape format
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Displays:
Pixel
picture element
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Screen Size
diagonal length of screen
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Aspect ratio
X pixels to Y pixels
▪ 4:3 – older displays
▪ 16:9 – widescreen displays
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Pixel color is determined by ?
Pixel color is determined by intensity of
3 colors – Red, Green and Blue (RGB)
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True Color what is it ?
8 bits for each color
▪ 256 levels of intensity for each color
▪ 256 * 256 * 256 = 16.7 million colors
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what is resolution ?examples
Resolution
▪ Measured as either number of pixels per inch or size of an individual pixel
▪ Screen resolution examples:
768 x 1024
1440 x 900
1920 x 1080
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what is the Picture size calculation?
▪ Resolution * bits required to represent number of colors in picture
▪ Example: resolution is 100 pixels by 50 pixels, 4 bits required for a 16 color image
100 * 50 * 4 bits = 20,000 bits
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Video memory requirements are,,,,,,,,,
significant!
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Interlaced vs. Progressive Scan diagram ?
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Diagram of Raster Screen
Generation Process
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Color Transformation Table
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Display Example diagram ?
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LCD – Liquid Crystal Display known as ?
Fluorescent light or LED panel
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how many colors in the LCD?
3 color cells per pixel
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Operation of the LCD
1 st filter polarizes light in a specific direction
▪ Electric charge rotates molecules in liquid crystal
cells proportional to the strength of colors
▪ Color filters only let through red, green, and blue
light
▪ Final filter lets through the brightness of light
proportional to the polarization twist
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LCDs (continued) what types of matrices ?
▪ Active matrix
▪ One transistor per cell
▪ More expensive
▪ Brighter picture
▪ Passive matrix
▪ One transistor per row or column
▪ Each cell is lit in succession
▪ Display is dimmer since pixels are lit less
frequently
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CRT Display Technology
- CRTs (similar to TVs)
- 3 stripes of phosphors for each color
- 3 separate electron guns for each color
- Strength of beam → brightness of color
- Raster scan
* 30x per second
* Interlaced vs. non-interlaced (progressive scan)
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OLED Display Technology traits ?
No backlight
Consists of red, green and blue LEDs
Each LED lights up individually
Very thin displays with panels less than
3mm thick!
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Printers comapsion between dots vs pixels ?
▪ Dots vs. pixels
▪ 300-2400 dpi vs. 70-100 pixels per inch
▪ Dots are on or off, pixels have intensities
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types of printers ?
- Typewriter / Daisy wheels – obsolete
- Impact printing - dot matrix – mostly obsolete
- Inkjet – squirts heated droplets of ink
- Laser printer
- Thermal wax transfer
- Dye Sublimation
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Creating a Gray Scale how diagram ?
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Laser Printer Operation
- Dots of laser light are beamed onto a drum
- Drum becomes electrically charged
- Drum passes through toner which then sticks to the electrically charged places
- Electrically charged paper is fed toward the drum
- Toner is transferred from the drum to the paper
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Laser Printer Operation (cont)
- The fusing system heats and melts the toner
onto the paper
7.A corona wire resets the electrical charge on the
drum
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Laser Printer Operation
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Laser Printer Operation (cONT)
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what other Computer Peripherals?
- Scanners
▪ Flatbed, sheet-fed, hand-held
▪ Light is reflected off the sheet of paper
▪ User Input Devices
▪ Keyboard, mouse, light pens, graphics tablets
▪ Communication Devices
▪ Telephone modems
▪ Network devices
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Network Communication Devices is just ?
▪ Network is just another I/O device
▪ Network I/O controller is the network
interface card (NIC)
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types of networking connection
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▪ Ethernet, FDDI fiber, token-ring
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Medium access control (MAC) protocols what does it define ?
Define the specific rules of communication
for the network
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Storage Hierarchy
– Performance is driven by latency and bandwidth.
– The more layers away from the CPU . . .
– . . . the higher the latency
– . . . the larger the capacity
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Storage Hierarchy
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Storage Hierarchy 2
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Magnetic Disk Technology
– Terminology
Platter?
a spinning disc within a drive, made of glass or aluminum, and coated with magnetic media
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Magnetic Disk Technology
– Terminology Head:
floats above the media, reading or writing the magnetically encoded data
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Magnetic Disk Technology
– Terminology track?
a ring on a single platter
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Magnetic Disk Technology
– Terminology
Cylinder?
a track across all platters
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Magnetic Disk Technology
– Terminology sector?
a wedge shaped slice of a platter
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Block
in the Magnetic disk terminology
the intersection of a track and a sector
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CAV (constant angular velocity):
used by HDD; disk always spins at the same speed.
Problem: wastes space on the outer rings
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– CLV (constant linear velocity):
The number of bits passing under the head is
constant. Faster angular velocity at the inner tracks; slower on the outer
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Raid: most Disks fail why ?
Disks often fail because they are at least partly mechanical. RAID (redundant array of independent disks) attempts to improve redundancy and bandwidth
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Raid combine 3 functions?
– Combine three primary functions:
– Mirroring
– Striping
– Parity checks
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RAID 0: Striping D?
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RAID 1: Mirroring D?
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RAID 5: Striping with distributed parity D?
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– RAID 10: Stripe across mirrors D?
https://s3.amazonaws.com/classconnection/655/flashcards/7082655/png/imagelpzgrx-14A60E254722BA1C6BF.png
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what does Memory hierarchy show ?
Memory hierarchy shows the inverse relationship between speed and capacity
in computing systems.
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– Magnetic disks have several kinds of latency:?
seek time, rotational delay, and
transfer time.
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how RAID try and fix ?
RAID attempts to compensate for latency and failures by employing striping,
mirroring, and parity checks.
