1.1.2 Hexadecimal
5.-Hexadecimal to binary
.-16 = 2⁴ so 4 binary digits quivalent to each hex .-For each hex digit write down the 4 bit binary .-e.g. B F 0 8 1011 1111 0000 1000
ASCII code
.-American Standard Code for Information Interchange .-Each character has an ascii code. It can be written in denary or hex. See picture
1.Numbers in hex
.-Base 16 → needs 16 digits: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, D, E, F .-As in binary (place value numbers) 16⁴ 16³ 16² 16¹ 16⁰ 65,536 4,096 256 16 1
HTML and colours
.-HTML often used to represent colors. .-The different intensity of red/green/blue, determined by hex FF 00 00 red 00 FF 00 green 00 00 FF blue FF 00 FF fuchsia
HTML
.-HyperText Mark-up Language .-For writing and developing web pages .-Uses <tags> to bracket a piece of code
MAC
.-Media Access Control Address .-MAC address refers to NIC → rarely changed so a particUlar device can be always identified .-Usually 48 bit →6hex digit .-Format NN-NN-NN-DD-DD-DD where NN-NN-NN: number of manufacturer DD-DD-DD: serial number device .-e.g. 00-1C-B3-4F-25-FE: made by Apple with serial number 4F25FE
NIC
.-Network Interface card .-Nic is part of the device
Mark up Language
.-Not a programming language .-Used in the processing, definition and presentaion of text
6.-Binary to Hexadecimal
.-Right to left ←.split binary into groups of 4 bis. If not multiple of 4, add 0s in the left. .-Convert each group to hexadecimal .-e.g. 101111100001 1011 1110 0001 B E 1
Memory Dump .
.-When the memory contents are output to a printer or monitor .-Value on the left is memory location. .-Powerful fault-tracing tool
8.-USES of hexadecimal in computing
1.-Defining colors in Hypertext 2.-Markup language (HTML) 3.-Media Access Control (MAC) addresses 4.-assembly language and machine code 5.- Debugging
3.-Hexadecimal to denary
1.-Multiply each digit for its place value 2.-Add them 3.-e.g. 4 5 A (256 x 4 = 1,024) (16 x 5=80) (1 x 10=10) 1024 + 80 + 10 = 1,114 (denary) You can also do hexadecimal to binary to denary. See image
Types of MAC addresses
1.-Universally Administered MAC Address: (UAA) .-most common .-set by manufacturer at factory 2.-Locally Administered MAC Address (LAA) Some sw used on mainframe systems needs all the MAC addresses into a strict format
machine code
Computer programming language consisting of binary or hexadecimal instructions which a computer can respond to directly. 8020 78 8021 A9 80 8023 8D 15 03
Denary-Hexadecimal-binary 0-15.
Denary Hexadecimal Binary 0 0 0000 1 1 0001 2 2 0010 3 3 0011 4 4 0100 5 5 0101 6 6 0110 7 7 0111 8 8 1000 9 9 1001 10 A 1010 11 B 1011 12 C 1100 13 D 1101 14 E 1110 15 F 1111
2.-Why is used hexadecimal to represent numbers?
Hexadecimal make it: 1.-Easier 2.-Faster 3.-Less Error prone to write code compared o binary e.g. easier type B5A41AFC than 1011 1001 1010 0100 0001 1010 1111 1100
4.-Denary to Hexadecimal
Two methods: 1)Trial and error. Place hex in the appropriate place value position: e.g. denary 2,004 256 16 1 7 D 4 (256 x 7) + (16 x 13) + (1 x 4) = 2,004 2) Divide by 16. Remainders read bottom to top 2004 / 16 % 4 125 /16 %13 7/16 %7 2004 → 7D4
ASCII code and web address
Web addresses can be represented in ascii. % → hex is being used e.g. www.hodder.co.uk %77 w %77 w %77 w %2E . %68 h %6F o %64 d %64 d %65 e %72 r %2E . %63 c %6F o %2E . %75 u %6B k .-sometimes hex address used as security feature
Assembly Code
assembly language is used to program the CPU. is made up of asmall set of command words called 'Mnemonics' .-Friendlier than machine code!