Unit 1 - Data Representation Flashcards
What are the four main uses of hexadecimal?
- Error codes refer to the memory location of where the error occurred.
- A Media-Access-Control (MAC) Address identifies a device on a network in the format of NN-NN-NN-DD-DD-DD (the first six digits are the manufacturer code, the last six digits are the serial number of the device).
- An Internet-Protocol (IP) Address is given to a device that joins a network (IPv4 is 32-bits, IPv6 is 128-bits).
- Hypertext Mark-up Language (HTML) colour codes are made up of a combination of red, green and blue (RGB). The amount of each colour used is represented by a hexadecimal code.
What happens during a logical binary shift?
For each shift to the left, the binary value is multiplied by two. For each shift to the right, the binary value is divided by two. This often results in an error as one or more bits may be lost from the shift.
How is text stored?
The American Standard Code for Information Interchange (ASCII) character set is 7-bits, whereas the Extended ASCII character set is 8-bits. However, both character sets are limited to Western language only.
The Unicode character set is 32-bits.
How is sound stored?
Sound is analogue data which must be converted to digital using an Analogue-Digital Converter (ADC) to be stored on a computer.
Amplitude measures the range of volume in a sound file in bits.
How can data be measured?
1 kibibyte (KiB) = 2^10 bytes.
1 mebibyte (MiB) = 2^20 bytes.
1 gibibyte (GiB) = 2^30 bytes.
1 tebibyte (TiB) = 2^40 bytes.
1 pebibyte (PiB) = 2^50 bytes.
1 exbibyte (EiB) = 2^60 bytes.
How do you calculate file size?
Image file size = image resolution (no. Pixels) x colour depth (bits)
Sound file size = sample rate (Hz) x sample resolution (bits) x sound length (seconds)
Why is it beneficial to compress data?
To save up the storage space used, reduce streaming and downloading/uploading times, reduce the bandwidth requirements and to reduce costs (e.g. if storing files using cloud storage).
What is lossy file compression?
File compression algorithms eliminate unnecessary data (e.g. removing sounds from a sound file that cannot be heard by the human ear). The original file cannot be reconstructed once it has been compressed, however, the files are smaller than those produced by lossless algorithms. Examples include MPEG and JPEG.
What is lossless data compression?
File compression algorithms temporarily reduce the file size, meaning that data from the original uncompressed file can be reconstructed following compression. No data is lost following the application of the lossless algorithms. The most common example is Run-Length-Encoding (RLE).
What is RLE?
Run length encoding (RLE) is an example of lossless file compression. It reduces the size of a string of consecutive, identical data items. The repeating unit is encoded into two values:
1. The first value represents the number of identical data items.
2. The second value represents the code (e.g. ASCII) of the data item.
