Memory Addresses

How Memory Addresses Are Used

How Memory Addresses Are Used Applies to DOS and Windows 9x only Windows NT and Windows 2000 use a different memory-mapping design

Memory Addresses Are assigned during the boot process BIOS or real-mode device drivers may only work if given a specific group of addresses (usually in the upper memory range between 640K and 1024K) Shadowing ROM (aka shadow RAM) ROM programming code copied into RAM to speed up system operation because of faster access speed of RAM

Input/Output Addresses Numbers used by devices and the CPU to manage communication between them Also called port addresses or ports

Input/Output Addresses

Interrupt Request Numbers and I/O Addresses for Devices continued

Interrupt Request Numbers and I/O Addresses for Devices

Direct Memory Access (DMA) Channels A shortcut method whereby an I/O device can send data directly to memory, bypassing the CPU

Direct Memory Access (DMA) Channels

Tying It All Together To allocate system resources and use them to manage hardware devices, at startup a hardware device is assigned: An IRQ by which it can signal the CPU that it needs attention Some I/O addresses by which the CPU and the device can communicate Some memory addresses that indicate where the program to manage the device can be stored Perhaps a DMA channel to speed up sending its data to memory

Configuration Data and How It Is Stored Also called setup information Information about the computer’s hardware Stored in one of these devices: DIP switches CMOS setup chip Jumpers

Setup Data Stored by DIP Switches

Setup Data Stored on a CMOS Chip

Setup Data Stored by Jumpers

Passwords Stored on CMOS Startup password Required by computer during boot process to gain access to the PC Also called power-on password

Protecting Data, Software, and Hardware Saving and restoring setup information in CMOS Keeping OS rescue disks Backing up the hard drive Documentation Damage from electricity

Saving and Restoring Setup Information in CMOS Two common utility software programs for backing up setup information to a disk to be used to recover lost setup information Nuts & Bolts Norton Utilities

Saving Setup Information Using Nuts & Bolts

Saving Setup Information Using Nuts & Bolts

Saving Setup Information Using Norton Utilities

Saving Setup Information Using Norton Utilities

Saving Setup Information Using Norton Utilities

Keeping OS Rescue Disks Allows you to boot a computer Essential for every computer

Backing Up Your Hard Drive Backup An extra copy of a file or files made to a different location or storage media Backup policy depends on what you are backing up

Documentation Keep hardware and software documentation well labeled in a safe place

Damage from Electricity Computers and data can be destroyed by two kinds of electricity Static electricity (ESD or electrostatic discharge) Power spikes, including lightning Practical protection against damage Never touch the inside of a computer when it is turned on Be grounded when computer is on Use devices for protection against electrical surges and lightning

Chapter Summary How individual computer components work together to perform tasks