Topic 1 of 6 · Form 5
Information representation and communication
Binary, denary, hexadecimal, BCD; binary prefixes (kibi, mebi) versus decimal (kilo, mega); two's complement and binary arithmetic with overflow; character sets (ASCII, extended ASCII, Unicode).
Notes for this topic 1 file, in order
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Data representation
Binary, denary, hexadecimal, BCD; binary prefixes (kibi, mebi) versus decimal (kilo, mega); two's complement and binary arithmetic with overflow; character sets (ASCII, extended ASCII, Unicode).
Multimedia
Bitmap images (resolution, colour depth, file size = width × height × colour depth), vector graphics (drawing objects and properties); sound (sampling rate, sampling resolution, file size); compression (lossy and lossless, run-length encoding).
Worked example: Calculate the size in MiB of a 3-minute stereo recording at 44.1 kHz with 16-bit resolution.
44 100 × 16 × 2 × 180 = 254 016 000 bits = 31 752 000 bytes ≈ 30.3 MiB
Networks
LAN, WAN; client–server and peer-to-peer; topologies (bus, star, mesh, hybrid); cloud computing; wired and wireless media; Ethernet and CSMA/CD; hardware (switch, router, NIC, WAP, bridge, repeater); IP addressing (IPv4, IPv6, subnetting, public and private addresses, static and dynamic); DNS; URLs.
Check yourself
- Represent −27 in 8-bit two's complement.
- Give one advantage of vector graphics over bitmaps.
- What is CSMA/CD?
Show answers
- 27 = 00011011 → 11100101
- They scale without loss of quality (and often have smaller file sizes).
- Carrier sense multiple access with collision detection – devices listen before transmitting and retransmit after random delays when collisions occur.
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