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Unit 5: Lets discuss the BIOS, CMOS, POST, and Boot Process! Rajeev Gupta (Mr. RAJ)

Unit 5: Lets discuss the BIOS, CMOS, POST, and Boot Process! Rajeev Gupta (Mr. RAJ) 15 Years of IT & Training Experience in

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Unit 5: Lets discuss the BIOS, CMOS, POST, and Boot Process! Rajeev Gupta (Mr. RAJ)

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  1. Unit 5: Lets discuss the BIOS, CMOS, POST, and Boot Process! Rajeev Gupta (Mr. RAJ) 15 Years of IT & Training Experience in Hardware and Networking. Training is my Passion. I am really excited about brining this information to you. I will do my best to give you a perfect place to launch an IT career and I promise it will help you tremendously in knowing how the PC works. You will be building on the foundation no matter where you go.

  2. BIOS • Basic Input Output System • A chip on the motherboard • BIOS is stored in the PC’s ROM chip • EPROM • Firmware • BIOS will support all hardware on an 286 AT PC • Drivers are required for all other hardware Mr. Raj Class: Operating Systems Lecture

  3. Firmware • Gray area between hardware and software • Software written permanently or semi-permanently to a computer chip • Used to control electronic devices • Implemented in PC with BIOS and CMOS

  4. BIOS • Basic Input/Output System • A set of software instructions stored on a chip on the motherboard • Enables basic computer functions • Common BIOS manufacturers: • AMD • AMI • AWARD • MR BIOS • PHOENIX • Many use shadowing

  5. Function of the BIOS • Stores a set of instructions to tell the PC how to control devices • Provides low-level hardware access • Tests hardware on startup using POST • Runs “bootstrap loader” after POST • After this the operating system takes over Mr. Raj Class: Operating Systems Lecture

  6. APPS OS AT computer BIOS Hardware The BIOS sits between the hardware and the Operating System Mr. Raj Class: Operating Systems Lecture

  7. BIOS updates • BIOS implemented either in: • ROM: Programmed at factory • Flash memory: Can update, “flash,” the BIOS • Update if you: • Have device problems or other bugs that PC manufacturer says are caused by BIOS problems • Have device problems that can’t be attributed to anything else; have exhausted all other troubleshooting avenues • Need to use new hardware options that are supported by motherboard but not by BIOS

  8. BIOS update sources • Links to BIOS updates and flashing utilities on PC manufacturer’s Web site • BIOS is tailored by each PC manufacturer • Don’t go to BIOS manufacturer’s Web site

  9. Determining the BIOS version • Open System Information • Record BIOS Version/Date field value • If present, record SMBIOS field value

  10. Flashing the BIOS • Determine current BIOS version • Go to PC manufacturer’s Web support pages • Compare available updates with current version • Download new BIOS version • Download flashing utility • Close all open windows • Open flashing utility; follow instructions • Restart PC

  11. BIOS update failures • Don’t update your BIOS unless you must • Never turn off your computer during a BIOS update • Connect to a UPS • Use the correct BIOS flash utility • Follow instructions exactly • Back up BIOS if possible

  12. Recovering from a failed update • Use BIOS backup to restore previous version • Use “boot block” • Use flash recovery jumper switch • Obtain new BIOS chip

  13. Bad CMOS battery • BIOS data retained due to CMOS battery • Older PCs had a soldered battery—not replaceable • Newer PCs have removable battery

  14. CMOS • Area of memory that stores BIOS configuration information • Battery provides power to CMOS • Type of computer chip: complementary metal oxide semiconductor • Can maintain information without a supply of power

  15. CMOS battery

  16. CMOS configuration • Configure with system setup utility • Built in BIOS • Locate on separate hard disk partition • Stored on disc • Access to utility varies by manufacturer • List of CMOS access keys: • http://murfsgarage.cybertechhelp.com/cmossetup.htm

  17. CMOS configurable settings • Date and time • CPU options • Optical drive options • Floppy drive options • Hard drive options • Serial port options • Parallel port options • Integrated devices • Plug and Play • Power management options • Virus detection • Boot password continued

  18. CMOS ROM BIOS CHIP Changeable hardware • RAM • hard drive • floppy drive etc. Unchangeable hardware CMOS Battery CMOS also acts as a clock Stores date and time • keyboard • pc speaker • video CMOS Updates to hardware, e.g. adding RAM or changing a hard disk are stored in CMOS

  19. CMOS • Complementary Metal Oxide Semi-Conductor • Stores roughly 64Kb of data • Part of the Southbridge in most PCs • Specs stored in CMOS must match hardware • Allows you to access the BIOS • When hardware is changed/updated, CMOS must be updated Mr. Raj Class: Operating Systems Lecture

  20. Accessing BIOS through CMOS setup • CMOS can only be accessed when the PC is booting • Key combination at start-up • Changes are stored on a NVRAM CMOS chip • AMI and AWARD BIOS – DEL key • PHOENIX BIOS – CTRL, ALT and ESC keys or F2 • The mouse doesn’t work in CMOS setup! Mr. Raj Class: Operating Systems Lecture

  21. The CMOS chip • CMOS is stored in SRAM chip called Non-Volatile Random Access Memory(NVRAM) • Stores data which is used by the BIOS • NVRAM is powered by CMOS battery • Modern BIOS is stored in EEPROM • EPROM and SRAM means motherboards are updateable • Older motherboards • Resetting CMOS Mr. Raj Class: Operating Systems Lecture

  22. AMIBIOS Main Menu Always document existing settings before making any changes Mr. Raj Class: Operating Systems Lecture

  23. Standard CMOS Features Mr. Raj Class: Operating Systems Lecture

  24. Advanced BIOS Features Mr. Raj Class: Operating Systems Lecture

  25. Advanced Chipset Features Mr. Raj Class: Operating Systems Lecture

  26. Power Mangement Features Mr. Raj Class: Operating Systems Lecture

  27. PNP/PCI Configurations This should be set to Yes Mr. Raj Class: Operating Systems Lecture

  28. Integrated Peripherals N.B. Exam - ECP or EPP mode allows printers to access DMA channels and are 10 times faster than bidirectional mode Mr. Raj Class: Operating Systems Lecture

  29. PC Health Status Mr. Raj Class: Operating Systems Lecture

  30. Frequency/Voltage Control Mr. Raj Class: Operating Systems Lecture

  31. Other CMOS Settings • Load High Performance defaults • Load BIOS setup defaults • Supervisor password • User password • Disconnect the battery for 1 hour to erase the password! • CMOS can also be cleared using a jumper Mr. Raj Class: Operating Systems Lecture

  32. Clear CMOS Jumper Mr. Raj Class: Operating Systems Lecture

  33. Troubleshooting CMOS • Loss of time/date settings • Chip creep • Voltage of new battery • Old PCs = 3.6 volt batteries • Newer PCs = 6 volt battery Mr. Raj Class: Operating Systems Lecture

  34. POST process Power-on self test • BIOS tests core hardware • BIOS tests video subsystem • BIOS identifies itself, including its: • Version • Manufacturer • Date • BIOS tests main system memory

  35. Beep codes • Inform user of errors before display is loaded • Vary by manufacturer • www.computerhope.com/beep.htm • Common beep codes: • 1 short beep = No problems found • 3 long beeps = Keyboard error • 8 short beeps = Video adapter memory problems • 9 short beeps = BIOS problem • 1 long + 3 short beeps = Memory error

  36. Numeric codes • Informs user of errors after display is loaded • Vary by manufacturer • IBM numeric code examples: • 151 = Real time clock failure • 161 = Bad CMOS battery • 162 = Configuration mismatch • 164 = Memory size mismatch • 201 or any 20# = Memory failure • 1762 = Hard drive configuration error

  37. The boot process • You turn on the power • Timer chip sends reset signals to CPU to prevent booting • Power supply performs internal checks; sends Power_Good signal to CPU • Timer stops sending reset signals to CPU • CPU loads BIOS and BIOS extensions • BIOS checks whether this is a cold or warm boot continued

  38. The boot process, continued • If cold boot, BIOS performs POST • BIOS reads CMOS and configures devices • Plug and Play devices detected and configured • BIOS determines which drive to boot from • BIOS reads the master boot record from drive • OS takes over and completes the boot process

  39. Boot devices • Used to load operating system • Current: • Internal hard disk • Optical drive: CD or DVD • USB drive: flash drive or external hard disk or optical drive • Network drive, using a PXE network interface card • Older: • Floppy disk drive • SCSI device • Zip drive

  40. Boot devices in the system BIOS

  41. BIOS-related problems • Devices misidentified • Wrong memory size reported during POST or available during booting • Hard drive inaccessible • System won’t boot from hard drive • System boots from the wrong device • Date and time incorrect or reset after computer is turned off

  42. POST-related problems • There’s no video; instead, the computer sounds 8 short beeps • The system emits 3 long beeps • The system emits 1 long and 3 short beeps • POST code 162 is displayed • POST code 164 is displayed

  43. CMOS-related problems Error messages: • Non-system disk or disk error • Display type mismatch • Memory size mismatch • CMOS checksum failure

  44. Startup Routine Step 1: POST Step 2: Bootstrap Loader Step 3: Master Boot Record Mr. Raj Class: Operating Systems Lecture

  45. A detailed look at POST • “Devices go forth and test yourselves” • Only checks devices listed in BIOS • Beep codes • Refer to motherboard manual • Text errors • “Missing NTLDR” • “Keyboard error or no keyboard present” • POST cards Mr. Raj Class: Operating Systems Lecture

  46. Startup Routine • 1. During the POST, the BIOS tells drivers to “test themselves” and report back • Problems are flagged either by beeps codes or by messages on the screen • e.g. 301 Keyboard failure • 2. Bootstrap Loader • 3. Master Boot Record • IO.SYS • NTLDR • After this the operating system takes over Mr. Raj Class: Operating Systems Lecture

  47. POST Error Codes Mr. Raj Class: Operating Systems Lecture

  48. BOOT Process in detail • CPU’s power good wire “wakes up” the CPU • CPU reads first line of POST program • Bootstrap loader runs • Check if disk is in FDD drive • Look for O.S. on boot sector of hard drive • NTLDR (Windows 2000/XP) or IO.SYS is loaded into RAM • Control is transferred from bootstrap loader to the O.S. • Core O.S. files, drivers and services are loaded into RAM Mr. Raj Class: Operating Systems Lecture

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