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Boot sequence manual - PC Desktops

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When you hit the power button on your computer a whole lot of stuff happens. We call this the boot process. In the days when I first started using computers there was literally a "boot disk", a floppy (5.25" not a 3.5") disk that told the system where to go and what to do so that the operating system would start up. Since then the boot sequence has become somewhat more complicated. So let me take you thru the steps the computer takes to get started. For my example I'm going to use a Windows XP system.

  1. First is the POST, this stands for Power On Self Test, for the computer. This process tests memory as well as a number of other subsystems. You can usually monitor this as it runs each test. After that is complete the system will run POST for any device that has a BIOS (Basic Input-Output System). An AGP has its own BIOS, as do some network cards and various other devices.
  2. Once the POST is complete and the BIOS is sure that everything is working properly, the BIOS will then attempt to read the MBR (Master Boot Record). This is the first sector of the first hard drive (called the Master or HD0). When the MBR takes over it means that Windows is now in control.
  3. The MBR looks at the BOOT SECTOR (the first sector of the active partition). That is where NTLDR is located, NTLDR is the BOOT LOADER for Windows XP. NTLDR will allow memory addressing, initiate the file system, read the boot.ini and load the boot menu. NTLDR has to be in the root of the active partition as do NTDETECT.COM, BOOT.INI, BOOTSECT.DOS (for multi-OS booting) and NTBOOTDD.SYS (if you have SCSI adapters)
  4. Once XP is selected from the Boot Menu, NTLDR will run NTDETECT.COM, BOOT.INI and BOOTSECT.DOS to get the proper OS selected and loaded. The system starts in 16-bit real mode and then moves into 32-bit protected mode.
  5. NTLDR will then load NTOSKRNL.EXE and HAL.DLL. Effectively, these two files are windows XP. They must be located in %SystemRoot%System32.
  6. NTLDR reads the registry, chooses a hardware profile and authorizes device drivers, in that exact order.
  7. At this point NTOSKRNL.EXE takes over. It starts WINLOGON.EXE that in turn starts LSASS.EXE, this is the program that display the Logon screen so that you can logon.

Posted on Nov 05, 2008

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How do I change the bios settings to boot from a dvd to down grade from windows 8 to windows 7 please.


Hi
To activate the BIOS utility, press <F2> during the POST while the
computer logo is being displayed.
To set the boot sequence in the BIOS utility, activate the BIOS utility, then select Boot from the categories listed at the top of the screen.
You can then choose the order in which the BIOS seeks bootable media. For your purposes the optical drive needs to be the first option. Do remember that during the boot sequence there are only about 5 seconds where it will say "Press any key to boot from CD......" after which it will revert to booting from the hard drive.
If you go to this site,
Drivers and Manuals
you can choose your model from the options lists and can then download drivers and documents which you may need after your downgrade.
Hope this is helpful, if so would you please register that with Fixya
Cheers

Dec 03, 2014 | Acer America Aspire Xc-105 Desktop...

1 Answer

Winfast boot sequence problem


Boot sequence problem? You set the boot sequence permanently in the Bios or System Setup. Normally when you boot the system the screen will tell you what key to hit to get into the Bios or Systems Setup.

You can set the boot sequence temporarily (just for the current boot cycle) by watching the screen when you boot and it will tell you which key to hit to change the boot sequence or boot order.

May 07, 2012 | ASUS PC Desktops

1 Answer

What can I do to fix this problem, my gr 500 is telling me to reboot and select proper device or insert boot media in selected boot device


You need to go into your Bios or System Setup and change the boot order or boot sequence. It sounds like you might be trying to boot from a Network or Lan. It could be that you are trying to boot from the CD drive but instead of having a operating system disc in the drive you might have a movie or music cd in the drive.

Reboot the computer and notice what key the screen says to hit to get into the Bios or System Setup and hit that key. Change your boot order or boot sequence. The best sequence is to have the CD Drive 1st and the Hard Drive 2nd. Changing this in the bios or system setup will make the change permanent. Just make sure when you boot the computer that nothing is in the CD drive unless you have a repair disc or operating system disc in it.

You could make a temporary change but then you will have to change it every time you boot. If you notice the screen when you boot it also gives you the key to hit to change the boot order or boot sequence. This will allow you to change it just for this time that you are booting.

May 03, 2012 | Gateway 500GR PC Desktop

2 Answers

When I turn on my computer, it goes to a black screen and says, "Disk Boot Failure, Insert Disk and Press Enter". I am also seeing an Error Code BIOHD-2 and it say Warning no drive detected. Can you help...


Possible tha the PC is infected and has the booting sequence faulty , some files are lost. you must reinstall the OS , format teh drive , then install an antivirus and finally the PC harware drivers.

Sep 19, 2010 | PC Desktops

1 Answer

Boot sequence problem while booting


your mocs cell waltage goes down.
CMOS cell gives power to bios flash memory when it goes to low bios forgot settings after power off.
So purchase new CMOS cell it is on motherbord change it then save settings then it not forgot settings even after power off.

Thanks for using fixya.

Jul 27, 2009 | IBM Lenovo ThinkCentre M55e PC Desktop

1 Answer

Laptop computer will not boot, error 'Can not read A: drive', a drive not installed


Check in your CMOS to make sure that your computer isn't searching for the A: drive, set it to disabled or off. Sometimes you need to tell the computer that the A drive doesn't exist, or it will always try to boot from it, regardless of what the boot sequence is set to.

May 05, 2009 | PC Desktops

2 Answers

Recovery disk needed


reboot
on reboot, enter BIOS setup, F1 Esc, whatever the prompts say
and change the boot sequence to a valid drive.
This may not work since you did not say what occurred to __kup the boot sequence

Sep 20, 2008 | Insignia D300a PC Desktop

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