PC Architecture Fundamentals Copyright © 1996-2003 Intel Corp. BIOS & POST Chapter 2.

PC Architecture Fundamentals

Copyright © 1996-2003 Intel Corp.Copyright © 1996-2003 Intel Corp.

BIOS & POSTBIOS & POSTChapter 2Chapter 2

CH2 Slide-2PC Architecture Fundamentals

BIOS & POST

OBJECTIVES: Upon completion of this topic, the participant will be able to do the following:

Identify areas of memory reserved for System BIOS.Illustrate the functional hierarchy of H/W, BIOS, & O/SRecognize the functions of POST.Recognize the functions of the Runtime BIOS.

IATT Web Site: http://iatt.intel.com


System BIOS A set of programs stored in

non-volatile memory (Firmware Hub) on the motherboard.

Non-volatile memory is not lost when the power is turned off.

Contains two components. Power On Self Test (POST)

a built in diagnostic program

Runtime Basic Input/Output System (BIOS) the bottom-most software layer which interfaces with the hardware and operating system.

Firmware is a combination of software and hardware. Program stored in ROM

Processor

Host Bus 133 MHz 64-bit

HubLink Bus

FWH

PCI Bus 33 MHz 32-bit

AGP Bus

System Memory

Audio

USB

LAN

IDE

South Bridge(ICH)

Keybrd

Mouse

Floppy

SerialParallel

Clock Gen

Host Clock

PCI Clock

USB Clock

Hublink Clock

LPC Bus

SM BusCNR

North Bridge(MCH)

SIO

BIOS & POST Overview


0009 FFFF0000 0000

000B FFFF000A 0000

000D FFFF000C 0000

000E FFFF000E 0000

000F FFFF000F 0000

0010 FFEF0010 0000

FEFF 00000010 FFF0

FFFF FFFFFF00 0000

640K SYSTEMMEMORY

128K VIDEORAM

128K I/OEXPANSION ROM

64K ROMOR DRAM

64K BIOSOR DRAM

HIGH MEMORYAREA

EXTENDEDSYSTEM MEMORY

8MB BIOS AREA

REAL MODEON BOARD DRAM

DISPLAY BUFFER

RESERVED FOR ROMON I/O ADAPTERS

BIOS EXTENSION OR RAM

ROM BIOS OR RAM

ON BOARD DRAM

ON BOARD DRAM

RESERVED FORSYSTEM

ADDRESS DESCRIPTION FUNCTION

1 Meg

System BIOS is decoded at the top of the memory map (4 GB) and also in the 1st 64K block below 1Meg (F0000h-FFFFFh) for compatibility.

The BIOS gets shadowed (copied) into DRAM after memory has been tested and verified to be functional. Shadowing provides faster

access to the BIOS during run time.


The System BIOS is decoded in the 1st 64K block of memory (0000-FFFF hex).

True

or

FalseFalseTop of memory and the 1st 64K

block below 1MB, between F0000h and FFFFFh for

compatibility

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Components of the System BIOS

POST

BIOS SetupUtility

Runtime BIOS

Executes at Power-On & System Reset

Initialize ALL components which need to be programmed so that system can boot up

(e.g., CPU, Memory, Chipsets, Timer, DMA Ctlr, Video, Floppy, HDD, USB, etc..)

Executes only when press “Hot Key” sequence to run SETUP

Always available as an interface between hardware & software


The Runtime BIOS part of the Firmware Hub code provides the Operating System* (O/S) and the programs access to the system devices.

APPLICATIONS

O/S: [BIOS / KERNEL / COMMAND PROCESSOR]

SYSTEM BIOS(RESIDENT)

HARDWARE

The Runtime BIOS isolates the O/S and applications from low-level hardware and provides low level interaction with hardware.

Runtime BIOS services perform I/O by directly addressing the H/W registers on the I/O chipsSystem BIOS is sometimes

called the resident portion since it is built into each PC by the manufacturer. A secondary (optional) or non-resident BIOS codes may read into DRAM from disk when the P/C loads an O/S.

Layered Operating System( *Non-Plug & Play O/S--e.g. DOS, Win 3.1)


APPLICATIONS



HARDWARE

Fill in the boxes with the proper labels on the left?

HARDWARE



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When system is reset, the CPU fetches, decodes, and executes the first instructions from address fffffff0h. The first instruction is typically a far jump to the main

POST code located just below 1 MB.The CPU executes the code fetched from the System

BIOS and the POST is started. POST detects, checks, & initializes installed components. POST configures the system according to battery backed

CMOS configuration RAM.The BIOS uses various hardware configuration parameters

that are stored in non-volatile CMOS RAM (these are preserved even when the machine is off).

During POST, the System BIOS provides access to a Set-up Program to examine and alter CMOS settings.

See Appendix for more Information


POST performs Initialization and Resource Allocation. Performs Initialization of sub-systems

Processor, Chipset(s) & Memory

Test sub-systems for proper integrity Memory & I/O Subsystems

Performs sub-system configuration (Boot Devices) Performs Plug and Play resource allocation

PCI devices, AGP, P2P (PCI-PCI bridges) etc..

Initializes installed sub-systems and external devicesKeyboard, Mouse, Floppy, COM Ports, LPT, Video etc..

Initiates Operating System boot up Software Interrupt 19 hex (INT19) bootstrap loader

POST (Power-On-Self-Test)


The POST runs through a series of tests to determine whether the machine is functional. POST Checks the System

CPU RegistersKeyboard ControllerRTC Rd/Wr CheckSys Bios ChecksumProgrammable Interval TimerDMA Chips & Page RegistersRam RefreshFirst 64K Ram and Parity Test

Jumps to the Bootstrap Loader (INT 19h) and gives control to the Boot Sector Code.

Initialize Master/ Slave DMA Initialize Master/Slave PIC Loads Interrupt Vectors RTC Checksum/Config. Screen Initialization & ROM

Search Check & Initialize remaining

Memory.

POST (Power-On-Self-Test)


POST (Power-On-Self-Test)POST normally stops on critical failures and indicates

errors by these messages: If the video is operational, POST display a message.

e.g.– “A: Drive Error No response from diskette drive” or “KB/Interface Error Keyboard interface test failed”

In some cases the problem is detected so early that the BIOS cannot access the video card to display a messageIn this case the BIOS will produce a beeping pattern on the

speaker to tell you what the problem is.

BEEP CODES are BIOS VENDOR dependent.

BEEP CODES are useful when you do not have a POST Card or other Diagnostic Tool.

Not all POST codes have BEEP codes. A POST Card will display current POST CODE on LED’s.


Example Beep Code DescriptionBeep Description

1 Refresh failure

2 Parity cannot be reset

3 First 64 KB memory failure

4 Timer not operational

5 Not used

6 8042 GateA20 cannot be toggled

7 Exception interrupt error

8 Display memory R/W error

9 Not used

10 CMOS Shutdown register test error

11 Invalid BIOS (e.g. POST module not found, etc.)


POST (Power-On-Self-Test)During POST, the BIOS

generates diagnostic progress codes (POST codes) to I/O port 80h. POST codes are

displayed with an add-in card (a.k.a. POST card) plugged into a PCI slot.

If the POST fails, execution stops & the last generated POST code is left at port 80h.This code is useful for

determining the point where an error occurred.

In addition to displaying POST codes some boards also shows power supply

voltage status on the motherboard.


POST Routines - Partial List The System BIOS initializes and tests the system and

writes diagnostic progress codes to I/O port 80h. Typical Code Checkpoints (partial list)

D0 - KBC, RTC enabled. Init code Checksum verification starting. D1- Kybd ctlr BAT test, CPU ID saved, going to 4 GB flat mode. D3 - Chipset init. start memory refresh, do memory sizing. D6 - Check recovery mode and verify main BIOS checksum. D8 - Uncompress the main BIOS module. D9 - Copy main BIOS image to F000 shadow RAM. 1A - Memory Refresh toggling. Going to check 15 µs on/off time. 30 - Display memory R/W test passed. 49 - Amount of memory below 1M found and verified. 54 - CPU in real mode. Going to disable gate A20 line... 8F - Hard disk controller reset done. Floppy setup to be done next


Example POST Sequence - AMI BIOS POST code = d0

POST code = d1

POST code = d2

POST code = d3

POST code = d4

POST code = d5

POST code = d6

POST code = d7

POST code = d8

POST code = d9

POST code = db

POST code = dd

POST code = df

POST code = e0

POST code = d

POST code = e

POST code = 10

POST code = 25

POST code = f0

POST code = f1

POST code = f2

POST code = 28

POST code = 29

POST code = 2a

POST code = 2b

Continues for a few hundred more writes

to I/O port 80h

POST code = e1

POST code = e2

POST code = e3

POST code = e4

POST code = e6

POST code = e7

POST code = e9

POST code = ea

POST code = eb

POST code = ec

POST code = ed

POST code = 23

POST code = 24


During POST, the BIOS generates diagnostic progress codes (POST codes) to I/O port ___.

80h

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Once O/S has booted, the Runtime BIOS (Basic Input Output System) interacts directly with the hardware. The Runtime BIOS is the bottom-most software layer in a

PC and functions as the interface between the hardware and the other layers of software (O/S, Applications, etc), isolating them from the details of the hardware.

Low level interface to devices such as Keyboard, Video, Printer, Disk and diskette, and Com.

Always available as an interface between hardware and software.

The runtime BIOS also contains system Interrupt Routines such as Keyboard Interrupt, Timer Interrupt, Real-Time-Clock Interrupt, etc.


BIOS (Basic Input/Output System)RUNTIME BIOS SERVICES EXAMPLE

Example 1 -- Initializing the COM PORT to Baud Rate = 2400; No Parity; 1 Stop Bit; 8 Data Bits MOV AH,00 ;INITIALIZATION

FUNCTION MOV AL,10100011B ;2400, NP,1 S, 8 DATA MOV DX,0 ;COM1 INT 14H ;BIOS INTERRUPT

Example 2 -- Change Video Mode (e.g., to 640 x 480) MOV AH,00 ;Set Video Mode Function MOV AL,12h ;Select 640 x 480 INT 10H ;Change Video Mode


reset

Chapter 2 Quiz1) Which location in the memory map is reserved for the

System BIOS?A) In the first 64K block of system memory.

B) In the first 64K block below 1 Mega Byte

2) When the system is ______, the CPU fetches, decodes, and executes the first instructions from address fffffff0h.

3) Which is NOT a component of the System BIOS?A) Runtime BIOS

B) Shadow BIOS

C) Setup Program

D) POST

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Chapter 2 Quiz

4) Which of the following is/are characteristics of the POST?A) It generates video display messages for all POST codes.

B) It normally stops on critical POST failures.

C) There is a corresponding beep code for every POST code.

D) POST codes & Beep codes are identical for all BIOS vendors.

5) Which of the following is/are functions of the Runtime BIOS component (not the POST component) of the System BIOS?A) Detects, checks, initializes installed components.

B) Performs sub-system configuration

C) Provides low level interaction with hardware.

D) Checks the 1st 64K RAM.

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REVIEW & SUMMARY

The functional hierarchy: BIOS services perform I/O by

directly addressing hardware registers on I/O chips.

The SYSTEM BIOS is called the resident portion and is built into each PC by the manufacturer.

The Runtime BIOS gets shadowed (copied) into DRAM after memory has been tested and verified to be functional.

APPLICATIONS



HARDWARE


REVIEW & SUMMARYThe functions of POST

POST is a built-in diagnostic program that detects, checks, & initializes installed components & configures the system according to the CMOS configuration RAM.

POST writes diagnostic progress codes to I/O port 80h. POST normally stops on critical failures.

The functions of the Runtime BIOS The Runtime BIOS (Basic Input Output System) is a low

level interface to devices such as Keyboard, Video, Printer, Disk and diskette, and Com.

Runtime BIOS functions as the interface between the hardware and the O/S and applications, isolating them from the details of the hardware.

End of Chapter 2End of Chapter 2

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PC Architecture Fundamentals Copyright © 1996-2003 Intel Corp. BIOS & POST Chapter 2.

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Transcript of PC Architecture Fundamentals Copyright © 1996-2003 Intel Corp. BIOS & POST Chapter 2.