Fix your computer - Part 2 - bootstrapping

March 9, 11:55 PMColumbus Computers ExaminerJanet Jones

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Laptop with top cover off

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Computer troubleshooting is not rocket science. But it also isn’t as simple as fixing a toaster. Unlike most appliances that only have one task to perform, a computer has as many roles as the programs installed on it. So like medical science and the complexity of the body, computer troubleshooting is an inexact science based on trial and error. Fix your computer-Part 1 emphasized what good doctors follow – first do no harm. It detailed a series of steps to solve a problem without making it worse or creating an additional problem:

1. Observe Symptoms - error messages, lockups, noises
2. Consider History - any new hardware or programs installed
3. Diagnostics - boot up tests, boot sequence
4. Research – Internet
5. Backup – registry and data
6. Apply the fix
7. Test the function

With symptoms, history, and preliminary diagnostics noted, the next step is observing the operating system’s “boot sequence” for clues. Boot is from the old word bootstrap, which was a strap on the top of a leather boot to grasp and pull a boot on. The old saying of “pulling yourself up by the bootstraps” meant using the leverage of something small to accomplish something bigger. The boot process of a computer activates the CPU to load a small initial program, called BIOS, stored in a read only memory chip (ROM) on the motherboard. The BIOS, short for Basic Input/Output System, in turn activates the main program, the operating system (OS), which is usually Windows or Linux.

Before the BIOS kick starts the operating system, it loads specific start-up instructions. First is the POST, the power on self-test, with its audible series of beep codes. Yes, beeps matter and were discussed in Part 1.

Next, is the retrieval of the system configuration instructions from the “complementary metal-oxide semiconductor memory” or CMOS, stored on the motherboard. The CMOS stores the date and time and the plug and play information the operating system needs to recognize the particular components in the computer. It also determines the boot up order, or which devices the system can use to start the operating system. At power on, most CMOS settings instruct the OS to look for a boot disk in a floppy drive or CD/DVD drive before accessing the hard drive. In the event the hard drive is faulty causing the operating system to stall, a Windows OS CD can be placed in the CD/DVD drive and used to start the computer. The Windows CD can check for bad sectors on the hard drive and possibly isolate them so the computer can boot into Windows and operate normally.

If no boot disk is present, the Master Boot Record (MBR) on the first sector of the hard drive is activated which then loads NTDLR which is the boot loader for Windows XP. At that point the “bootstrap” has done its job and the Windows operating system is in control. Windows rechecks the system memory and loads the device drivers it needs to control peripheral devices, like mouse, keyboard, printer, optical drives, etc. Finally, a logon screen appears and the user can access the computer.

Understanding the boot process of a computer is the foundation for troubleshooting those pesky error messages that may crop up after pushing the power button. Stay tuned for Part 3 where the real fun begins -- computer error messages and Murphy’s Law: what can go wrong, will go wrong.