EET 450 Chapter 2 – How hardware and Software Work Together

The BOOT process  CPU executes instructions sequentially. On power on – a power-on-reset is usually invoked. Program execution begins from a predetermined memory location (FFFF0h) This location typically contains only an unconditional jump – to the beginning of BIOS boot routine BIOS – Basic Input Output System

The BOOT process  BIOS leads the computer through the boot process Cold Boot –Power On Self Test (POST) –Verify boot settings in CMOS –Load Master Boot Record (MBR) from boot device –MBR contains location of OS boot routine (usually) Warm Boot –Skips POST

The BOOT process  The BIOS load routine resolves resource assignments – either statically or dynamically PNP devices allow automatic assignment  IRQ – Interrupt Request Vectors  I/O Addresses – physical address of I/O device/port

The BOOT process  Memory Addresses – portions of memory space assigned to ROM  DMA Channel – Direct Memory Access channel

OS Load  MBR directs CPU to routine that will complete loading the operating system  An I/O module containing device drivers and parameters for operating installed physical resources is loaded (IO.SYS)  A User Interface is loaded to display information to user and allow keyboard/mouse input

OS Load  Initial (setup) programs are executed.  Memory resident programs are loaded into memory with appropriate resource redirection.

Interrupts  IRQ – Interrupt Request Number Provides direction to interrupt vector – location of Interrupt Service Routine (ISR)

Memory Addresses  Memory Addressing Segmented Memory REAL mode memory addressing  Memory Map

Input/Output Addressing  The CPU provides separate methods & instructions for addressing memory and I/O  Table 2-6 contains normal IRQ and Addressing assignments

Assignment  Read Chapter 3  Start research on Motherboards/Chipsets  Review LINKS