Unit 1

WHY HEXADECIMAL SYSTEM (instead of Binary)? [2019, 2024]

1. It uses the values 0 to 9 and A to F. Uses fewer characters // shorter

2. Easier to read / write / understand

3. Less likely to make mistakes // less error prone

4. Easier to debug

USES OF HEXADECIMAL SYSTEM  [2018, 2020]

Error Codes

1. Often shown as Hexadecimal values

2. Refers to the memory location of the error

3. The Programmer interprets the Hexadecimal error code, diagnose and corrects the error

MAC ADDRESS [2019]

1. A Media Access Control (MAC) address is a number which uniquely identifies a device on the internet.

2. The MAC address relates to the network interface card (NIC) inside of the device.

3. Expressing MAC addresses in hexadecimal format makes them easier to read and work with.

4. MAC addresses consist of 12-digit hexadecimal numbers.  

5. The format being used is either MM:MM:MM:SS:SS:SS or MMMMMM-SSSSSS.  

6. The first 6 digits of the MAC address represent the ID of the adapter manufacturer while the last 6 digits represent the serial number of the adapter.

7. E.g. D5-BE-E9-8D-44-9C

8. Types of MAC Address: 

   1. • UAA (Universally administered MAC Address)- Most common, set by the manufacturer at factory and can’t be changed

      • LAA (Locally administered MAC Address)- used if administrator wishes to change

HTML

1. Hex can be used to represent colours on web pages and image-editing programs using the format #RRGGBB (RR = reds, GG = greens, BB = blues). 

2. The # symbol indicates that the number has been written in hex format.

3. Each primary colour – red, green, and blue and their different intensities is characterized by two hexadecimal digits.

4. As one hex digit represents 4 bits, two hex digits together make 8 bits (1 byte). 

5. The values for each colour run between 00 and FF. In binary, 00 is 0000 0000 and FF is 1111 1111. That provides 256 possible values for each of the three colours.

6. #FF0000 will be the purest red, #00FF00 will be the purest green and #0000FF will be the purest blue

7. Black is #000000 - no red, no green, and no blue. White is #FFFFFF.

8. E.g. orange can be represented as #FFA500, which is (255 red, 165 green, 0 blue)

Internet Protocol (IP) addresses

1. Full-Form: Internet Protocol

2. Purpose: It identifies the connection of a computer on the internet.

3. Bits: IPv4 is a 32-bit (4 bytes), and IPv6 is a 128-bits (16 bytes) address.  IPv4 address is written in denary or hexadecimal form while  IPv6 is represented by a hexadecimal number 

4.  IPv6 uses a colon (:) rather than a decimal point (.) as used in  IPv4.

5. Example of IPv6 address  2001:0db8:85a3:0000:0000:8a2e:0370:7334

6. Address: The IP address is assigned by the network administrator or Internet Service Provider.

7. IP Address is the logical address of the computer.

Explain the differences between the binary number system and the denary number system. [2017]

• • A binary number system is a base-2 system, A denary number system is a base-10 system

• • A binary number system uses 0 and 1 values, A denary number system uses 0 to 9 values

• • A binary number system has units/ placeholders/column headings that increase by the power of 2, A denary number system has units/ placeholders/column headings that increase by the power of 10

• • Binary has more digit for the same value// Denary has less digits for the same value

Text, sound, and images

Character sets

ASCII

• American Standard Code for Information Interchange

• Set up in 1963

• Consists of 7-bit codes (0 to 127) that represent letters, numbers, and characters found on a standard keyboard

• Uses one byte to represent a character

• E.g. 'A' is represented by 65 while 'a' is represented by 97

• Extended ASCII uses 8-bit codes (0 to 255 in denary) that include non-English characters and some graphical characters

• Disadvantage: does not represent non-Western languages like Hindi, Chinese, etc.

Unicode

• Represents all languages of the world

• Support all Operating systems, search engines, and browsers

• Overlaps with the 128  characters of ASCII

• Uses 4 bytes per character

Representation of Images

• An image is made up of tiny dots called pixels

• Each image has a resolution and a colour depth

  • Resolution- Number of pixels wide and number of pixels high

  • Colour depth- Number of bits that are used to represent each colour, E.g 8-bit, 16-bit or 32-bit (the higher the bits, the greater the range of colours)

Representation of Sound

• Sound waves are vibrations in the air (human ear senses and interprets them as sound)

• Each sound wave has a 

  • Frequency

  • Wavelength

  • Amplitude

• Sound waves vary continuously //analogue in nature

• Sampling: measuring the amplitude of the sound wave using ADC

Sampling Resolution (bit depth)

•  The number of bits per sample (the number of sound samples taken per second and measured in Hz-hertz)

• Larger sampling resolution means: [2024]

  • More bits are allocated to each amplitude

    • Amplitudes can be more precise

    • A wider range of amplitudes can be recorded

  • larger dynamic range

  • better sound quality

  • less sound distortion 

  • larger file size

  • longer time to transmit/download/stream

  • requires more processing power

CD's have 16-bit sampling resolution and a 44.1 KHz sample rate (44100 samples every second)

• A binary digit is referred to as a BIT

• 8 bits is a byte

• 4 bits is a nibble

• Byte, Kibibyte(KiB), mebibyte(MiB),gibibyte(GiB), tebibyte(TiB),pebibyte(PiB), and exbibyte(EiB) areall larger units of measurement