Computer Hardware

Chapter 5

Motherboard

• 1: Ports

• 3: Expansion slots

• 6: Central processing unit

Motherboard

• 8: RAM sockets

• 12: ROM BIOS

• Data bus: moves data

RAM

• Random access memory

• Blackboard: constantly creating info then erasing

• Volatile

• Capacity measured in megabytes– Holds data to be processed

– Holds instructions

– Holds results until stored

• Access time: nanoseconds

• Big impact on performance of system

Virtual Memory

• Operating system uses portion of hard drive as extension of RAM

• Can handle programs which require more RAM

• Slows performance

Central Processing Unit

• Gets data and instructions from RAM

• Processes data

• Sends results to RAM

Central Processing Unit Performance

• Clock speed measured in MHz– Heart beat: how fast can instructions

be executed– New chips up to 1,000 MHz

• Cache memory– Rapid access to frequently used data

• First look for data in cache memory

– Level 1: on CPU– Level 2: separate chip

• Fast chip without adequate RAM will be slow

ROM

• Read Only Memory

• Not volatile, permanent

• Generally can not change instructions

• BIOS: tells CPU where to find operating system and determines how peripherals will share resources

Boot process

• Power up: power light is on

• Start boot program: execute instructions in ROM

• Power-On Self-Test: checks monitor, RAM, keyboard, disk drives

Boot process continued

• Load operating system into RAM: – Will look in a: drive if it contains

disk

• Check configuration and setup files

• Ready

Plug and Play

• Computer system automatically detects and configures expansion cards and devices

• Connect a new device to system such as a new printer

• Restart computer

• Operating system finds device and installs drivers, if available

• Greatly simplifies process of adding expansion cards and peripherals

CD-R

• Compact-disk recordable– Can write data on it but can not

erase and rewrite– Uses

• Music

• Back up data– Hold equivalent of 500 floppies

• CD-RW– Compact-disk rewritable

• Can erase and rewrite data