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CCNA 1 v3.0 Module 1 Introduction to Networking. Objectives. Requirements for Internet Connection. PC Basics. PC Basics. PC Basics. PCI Expansion Slots. AGP Expansion Slot. PC Basics. Network Interface Cards. NIC and Modem Installation. High-Speed and Dialup Connectivity.
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PCI Expansion Slots AGP Expansion Slot PC Basics
IRQ, I/O port channels and Base Memory Addresses. • IRQ is an acronym for Interrupt ReQuest. An IRQ is a piece of circuitry built into the motherboard that connects one device/part to the CPU (Central Processing Unit). It lets the device interrupt the CPU so that jobs can be allocated and problems dealt with. • Devices connect to CPU when: • A task is finished • The device needs more instructions • Faults are developed
Data Representation • Character coding schemesASCII, Unicode • Unicode – International 16-bit coding system which can represent 65536 different characters • Binary number system • Binary Coded Decimal (BCD)each decimal digit has its own 4-bit binary code • Boolean valuesonly True or False • Digitised soundMIDI • Bit-mapped graphics
Binary number system • Numbers can be represented in a computer in a number of different ways, e.g. 25 in ASCII would be: • 0011 0010 0011 0101 • Alternatively in pure binary draw a table of powers of 2. Then find the largest power of 2<=25 (16). Subtract 16 from 25 and repeat • Value 128 64 32 16 8 4 2 1 0 0 0 1 1 0 0 1 16 + 8 + 1 = 25 • To translate from binary to decimal perform same process backwards • Value 128 64 32 16 8 4 2 1 0 1 0 0 0 1 0 1 64 + 4 + 1 = 69
Binary • Example • The yable shows numbers 0 1- in 4-bit binary code.
Boolean Values • A Boolean variable can only have one of two values, true or false • Represented by a 1 or a 0 • Useful to be able to use a binary bit to show if something is true or false, e.g: • To show whether a disk drive is connected • To show if the ‘break’ key is pressed’ • Single bits used in this way are called Flags
Main Memory Computer Memory • 250 bytes = 1 Petabyte Pb • 260 bytes = 1 Exabyte Ex • 270 bytes = 1 Zettabyte Zb • 280 bytes = 1 Yottabye Yb
Four-Octet Dotted-decimal Representation of 32-Bit Binary Numbers