Chapter 1: Binary Systems and Hexadecimal

Bases:

Binary = 2,

Denary = 10,

Octal = 8,

Hexadecimal = 16

These are the values that each of these number systems are oriented with.

Memory:

2³ bits is 1 byte.

2¹⁰ bits is 1 KB (kilobyte).

2²⁰ bits is 1 MB (megabyte).

2³⁰ bits is 1 GB (gigabyte).

2⁴⁰ bits is 1 TB (terabyte).

2⁵⁰ bits is 1 PB (petabyte).

Binary is used to denote the ‘on’ and ‘off’ state of a computer. It is used in computer registers. '1' is used to denot the 'ON' state, whereas '0' is used to denote the 'OFF' state.

HTML stands for HyperText Mark-up Language. It is the language used for developing web pages.

MAC Address:

It is the unique number that identifies a device on the Internet. It is made of 48 bits, in the format NN:NN:NN:DD:DD:DD. The first half identifies the manufacturer and the rest identifies the serial number of the device. The MAC Address refers to the NIC (network interface card).

There are 2 types of MAC Address: UAA (Universally Administered MAC Address) and LAA (Locally Administered MAC Address). UAA is rarely changed. LAA is changed in cases of mainframes adhering to a strict format, filtering of a firewall, and also to bypass network restrictions.

ASCII (American Standard Code for Information Interchange):

These codes represent characters such as those on a computer keyboard, by hexadecimal or decimal values; a-z is 97-122 in decimals and A-Z is 65-90 in decimals.

Web addresses:

ASCII codes are used to represent websites such as www.abcd.com. Hexadecimal codes are used to represent web addresses to avoid copy-pasting a fake URL despite the lengthy process.

Machine/Assembly codes:

These codes are 1s and 0s, the language that a computer understands. This is useful for programmers when troubleshooting problems and bugs, but it is disadvantageous in terms of high risk of mistakes as making mistakes is very likely when typing in a sea of 1s and 0s. Thus, these codes are represented by hexadecimal to better comprehend them and avoid making mistakes.