Basics of Information Technology: Units, Number Systems, Software and Logic
What this domain tests
Basics of Information Technology is the foundation unit: the data-to-information chain, units of storage, the four number systems and their conversions, character coding, logic gates, and the system-versus-application software split. Most items are one or two marks, so a single wrong positional weight loses the whole answer.
Storage and software
Data are raw facts; information is processed data that supports a decision. Capacity climbs bit → nibble (4 bits) → byte (8 bits) → kilobyte (1024 bytes) → megabyte → gigabyte → terabyte → petabyte. System software runs the machine (operating system, language translators, utilities); application software does the user's work and is either general-purpose (word processor) or customised/tailor-made (a school's own result system).
Number systems
Binary (base 2), octal (8), decimal (10) and hexadecimal (16, digits 0–9 plus A–F for 10–15). Decimal to binary: divide repeatedly by 2 and read the remainders from last to first. Binary to decimal: multiply each digit by 2 raised to its position, counting positions from 0 at the rightmost bit. Shortcut: group three bits for octal and four bits for hexadecimal, always starting from the right.
Worked example
Convert 45 to binary, then to hexadecimal. 45 ÷ 2 = 22 remainder 1; 22 ÷ 2 = 11 remainder 0; 11 ÷ 2 = 5 remainder 1; 5 ÷ 2 = 2 remainder 1; 2 ÷ 2 = 1 remainder 0; 1 ÷ 2 = 0 remainder 1. Reading upwards: 101101. Check: 32 + 8 + 4 + 1 = 45. Pad to two nibbles from the right: 0010 1101 → 2 and 13 → 2D. So 45 in decimal is 101101 in binary and 2D in hexadecimal.
Traps
- Starting the place value at 2 to the power 1 instead of 2 to the power 0.
- Writing a hexadecimal value as digit pairs like 12 instead of C.
- Mixing bit and byte: 100 Mbps is about 12.5 MBps.
- Calling the operating system application software.