Operating System

•Provides a set of services to system users•Manages memory (primary and secondary) and I/O devices•Exploits the hardware resources of one or more processors

Multitasking•Multitasking is the ability to execute more than one task or program at the same time.•CPU switches from one program to another so quickly that it gives the appearance of executing all of the programs at the same time.

CPU

• Central Processing Unit (the Brain of the Computer where decisions are made)

• Several types over the years– Single Core (one brain – one decision at a time)– Dual Core (two brains – two decisions at a time)– Quad Core (four brains – four decisions at a time)– There are more than this but these are the ones

that consumers buy for the most part.

OS – 32 and 64 Bit

• Two versions of Windows 7– 32 bit version (where you have 32 bit streams of data

going into a CPU and 32 bit streams of data coming out)– 64 bit version (where you have 64 bit streams of data

going in and out of the CPU– 64 bit doubles the amount of data that can be dealt

with by the CPU.• Two version of Mac OS – Tiger (32 bit) Snow L. (64

bit)• Ubuntu (64 bit).

How A System Works•Wake up Call – power on•Execute Bios – instructions kept in Flash Memory (type of read-only memory which examines system hardware)•Power-on self test (POST) checks CPU, memory and basic input –output systems (BIOS) for errors