U2T3 (2) - Hardware & Software Flashcards Preview

CCEA AS Digital Technology > U2T3 (2) - Hardware & Software > Flashcards

Flashcards in U2T3 (2) - Hardware & Software Deck (178)
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What is a port?

The interface/point of attachment to system unit.


What might a cable do?

It often attaches external devices to the system unit.


What are connectors?

Ports have different types of these and so they are used to join a cable to a device.


What are male connectors?

Connectors with one or more exposed pins.


What are female connectors?

Connectors with holes to accept the pins from male connectors.


What are the 3 types of ports in a computer?

Serial, parallel + USB.


What is a serial port?

Type of interface that connects a device to the system unit by transmitting data only one bit at a time. They usually connect devices that don't require fast data transmission rates e.g. mouse/keyboard/modem.


What is a parallel port?

Interface that connects devices by transferring more than one bit at a time. Many printers connect to the system unit by this type of port.


What is a USB Port?

Can connect up to 127 different peripheral devices with a single connector type, greatly simplifying process of attaching devices to PC.


What is file format?

When data stored within a file has structure and organisation e.g. jpg/wav/doc/xls/pdf


What does a computer need in order to work?

To have data flowing through the CPU under the control of a program. This data has to come from somewhere e.g. stored file.


How does the data flow work when a program is loaded from a stored file to produce an output?

File held on hard disk/secondary storage, loaded by a program into main memory, manipulated by a program in CPU + output produced.


Give examples of outputs?

Data files, screen images (graphics/text), moving images (video/animation) + sound (music/voice)


What is data compression?

Reducing the space occupied by a large file.


Why might you compress a data file?

For backing store or transferring it over a network.


How does data compression work?

Uses a series of algorithms to reduce the amount of real space taken up by data on a storage medium.


What is zipping the data?

The process of compressing data files.


How does zipping data files work?

Reduces the numbers of characters a file has. Uses the LZW algorithm to reduce memory/storage required by large files.


What does the LZW algorithm do?

Looks for repeating patterns in data being compressed and replaces them with a single character.


How do you calculate the compression ratio?

Original data size / compressed data size


What is the purpose of data compression?

Make files smaller for email, copying when streaming + reducing transfer time.


What is picture compression used for?

Storing images more economically or faster transfer of images


What techniques are used for picture compression?

Redundancy, lossless compression schemes, jpeg + mpeg format.


How does redundancy work for picture compression?

Repeated data describing the same element of an image. Common technique in compressions schemes is identification of this. E.g. Image with solid background colour, can be more efficient to store info that next 500 pixels are same, rather than repeating pixel data 500 times.


How do lossless compression schemes work for picture compression?

Allow the original images to be recreated, others are lossy and generally involve a loss of resolution in parts of the image where experience shows it will be least noticed.


How does JPEG format work for picture compression?

Joint Photographic Experts Group. Used for still images + works by identifying areas of image which are similar - Arrangement of pixels repeated elsewhere in image , perhaps after scaling/rotation. More efficient to store info about these similarities than to repeat data.


How does MPEG format work for picture compression?

Motion Pictures Experts Group. Used for moving images e.g. video + work by delta compression. To cope with high demands of TV standard pictures (25 separate frames transmitted every second in UK). Full picture sent occasionally (5 times per second) Between frames, info containing only changes to image is transmitted. Uses less data where pic is relatively static as with title/caption.


Windows Bitmap IPC:
File extensions, lossless?, type + comments.

BMP, yes, still image bitmap, uncompressed data one of the standard formats.


Tagged Image File Format:
File extensions, lossless?, type + comments.

TIF/TIFF, yes, still image bitmap, compressed data, one of the standard formats.


Graphics Interchange Format:
File extensions, lossless?, type + comments.

GIF, yes, still image bitmap, good for images with large areas of solid colour. As 8 bits are used, only 256 distinct colours can be represented. Simple animated version available suited to web graphics.