Hardware II

Content of the lesson:

Graphic Card

This component is used for visual output (graphic display) of what is happening inside the computer. Graphic card can be a separated card which should be inserted into a slot (a special AGP or PCI-E slot) or it can be integrated on the motherboard. Each card contains its own processor, so called GPU. A graphic card (or also graphic adapter, adapter, videocard) can control single points (pixels) on the output device (usually monitor), set the right brightness and color for them. Graphic cards with support for 3D operations are commonly used nowadays.

Parameters of Graphic Cards

• Resolution - This parameter says how many image points (pixels) will be displayed in horizontal and vertical direction on the output device.
• Color depth - This parameter says how many colors will be used on the output device. Examples:
  • 1bit color (2¹ = 2 colors) - Mono Color (bit 0 = white and bit 1 = black)
  • 4bit color (2⁴ = 16 colors)
  • 8bit color (2⁸ = 256 colors)
  • 16bit color (2¹⁶ = 65 536 colors) - High Color
  • 24bit color (2²⁴ = 16 777 216 colors) - True Color
  • 32bit color (2³² = 4 294 967 296 colors) - True Color
• Capacity - Written in GB nowadays. In case you set your color depth to 24 bits (TrueColor) and resolution to 1280 x 1024 pixels it means that every pixel on the screen will need 24 bits (=3 Bytes - every item of RGB color is saved in one Byte). When using this resolution and this color depth the calculation is simple: 1280 x 1024 x 3B = 3 932 160 B which means almost 4 MB for the screen.

  
zdroj: Wikimedia Commons [1] [2]

Hard Drive

This is an external memory of a computer which can be used for storing data for a long time. Hard drives usually have high capacity, are energetically independent which means that data is not lost after disconnecting the power supply but it remains on the hard drive. This component uses the principle of magnetic data recording and is vulnerable to damage, especially when it is turned on - you cannot make bigger vibrations or crashes. Hard drive is being marked as HDD. The most famous producers are: Seagate, Western Digital, IBM, Quantum, Fujitsu.

     
zdroj: Wikimedia Commons [1] [2]

HDD Parameters

• Capacity - hundreds of GB nowadays
• Access time - in milliseconds
• Speed or rotation - for example 5400 or 7200 rpm
• Transfer speed - usually tens of MB/s
• Size of cache memory - 512kB, 2M, 8M

Principle of Writing and Reading

HDD uses the principle of magnetizing a material and works with two states of information – 0, 1.

• Writing - Coil which is under electric current creates a magnetic field which is led through the core of the writing head inside the magnetic layer.
• Reading - It is based on the principle of electromagnetic induction. That means that an electric current is inducted inside the coil when the head finds a change from 0 to 1 or vice versa.

Structure of Data on HDD

Hard drive consists of several discs which ar placed above each other on the same axis. Discs are made from metal and there is a magnetic layer on them. The reading/writing head is very close to the disc. These heads are hovering on an air cushion so it is important to prevent any dust to get here. Each hard drive is hermetically closed. A hard drive contains different mechanisms, electronics and its own small motor.

A hard drive has to be formatted before saving data to it. It is similar as a drawer with many things. The content can be easily mixed so you have to create sections. The same procedure should be done with a hard drive. The formatting process creates sectors and tracks. Tracks are concentric circles and there is a particular amount of sectors in each track. Tracks which are above each other (the same tracks on every disc) create so called cylinder. Data are written to a hard drive in cylinders. All tracks contain the same number of sectors and all sectors can store the same amount of data.

Types of HDD

Hard drives are divided according to the interface for connecting them.

• ATA (IDE) - Two devices can be connected to this interface (hard drive or optical drive). It is necessary to switch one as "master" device and the other one as "slave" device. This setting is done using jumpers.
• SATA - You do not have to divide devices into "master" and "slave" ones. Every device is connected with a single cable straight to the motherboard.

<     
source: www.gamespot.com, www.gamespot.com

source: www.wdc.com

     
source: www.askdrtech.com, www.askdrtech.com

Jumpers

• Master - represents the setting when a main (control) drive is connected together with a second (subordinate) drive
• Slave - represents the setting when a subordinate drive which is connected together with a second (main) drive
• Cable Select - represents setting when the main and the subordinate drives are identified according to their connection to the cable. This requires usage of a special cable which can separate control and subordinate drives

source: www.viprasys.org

Animation (hard drive)

Alternativní obsah, třeba obrázek.

Optical Drives

CD

This is an optical storage medium with capacity of 650-700MB. Data is stored into tracks in shape of a spiral which starts in the middle of the disc. It is also divided to sectors. The pitch of the spiral is 1,6um, width 0,6um and you can find so called pits (holes) and lands (smooth areas). Reading data is done using a laser and optical elements inside the drive. Disc contains a reflex layer and if the laser falls on it through the set of lens, the signal is reflected from the reading device (photosensitive element) which converts it to an electric signal (0, 1). This is done in case that the laser signal reaches a land. Otherwise, when it reachs a pit, the signal is vanished and the reading device does not catch anything.

CD drives can use the interface ATA or SATA, access time is around 100ms. Transfer speed depends on the type of disc, for example 1x 150kB/s, 2x 300kB/s, 24x 3600kB/s.

There are four servomechanisms inside the device for rotation, sharpening, searching for track and tracing a track.

Example

Calculation of the capacity of music CD

44 100 x 2 x 2 x 74 x 60 = 783 216 000 B

• 44 100 - number of samples for one change
• 2 - resolution 16 bits on a sample, that means 2 bytes
• 2 - 2 channels (stereo)
• 74 - max. 74 minutes of music
• 60 - converting minutes to seconds

     
source: www.uai.fme.vutbr.cz, repairfaq.ece.drexel.edu

     
source: micro.magnet.fsu.edu, micro.magnet.fsu.edu

source: www.svethardware.cz

• CD-ROM (Compact Disc - Read Only Memory) - It is made by pressing, designed for reading only.

  
  source: www.primerpc.com

  
  source: www.sammt.net

• CD-R (Compact Disc – Recordable) - Allows you to write data using a burning drive (CD-RW drive, burner). The writing procedure is possible only once. You can also write on a disc without closing it and later burn another data to it.

  
  source: www.primerpc.com

  
  source: www.sammt.net

• CD-RW (Compact Disc – Rewritable) - Data can be written repeatedly (it can be deleted and burned again). The reliability and durability is quite lower than at pressed CD-ROM.


source: www.sammt.net

DVD

This technology is similar to CD. The difference is in the density of recording data. Another difference is the possibility to save data from both sides and also in two layers. Reading is done using the laser on one or on the other side. The top layer is semi-permeable.

source: dictionary.zdnet.com

source: encyclopedia2.thefreedictionary.com

• DVD-ROM
• DVD-R
• DVD-RW

Blu-Ray

This is a high-capacity medium designed mostly for video in a high definition. The title was derived from the color of laser which uses the wave length of 405nm. Thanks to this parameter you can store much more data on a standard 12cm disc than at DVD which uses a standard red laser with the wave length of 650nm.

source: manifest-tech.com

source: www.vgchartz.com

Animation (CD and DVD)

Alternativní obsah, třeba obrázek.

Environmental box

Questions

1. Which important parameters of graphic cards do you know?
2. What is the difference between VGA and DVI?
3. How is the data stored on a hard drive?
4. Which structure does a hard drive have?
5. Tell several ways of connecting hard drives to a motherboard.
6. Characterize CD, DVD and Blu-Ray, describe differences.