Hardware Reference
In-Depth Information
in question was at least loaded and partially running. Combine this information with the
knowledgeofthebootsequence,andyoucanatleasttellhowfarthesystem'sstartuppro-
cedurehadprogressedbeforetheproblemoccurred.Youusuallyshouldlookatwhichever
files or disk areas were being accessed during the failure in the boot process. Error mes-
sages displayed during the boot process and those displayed during normal system op-
eration can be hard to decipher. However, the first step in decoding an error message is
knowing where the message came from—which program actually generated or displayed
it. The following programs are capable of displaying error messages during the boot pro-
cess:
OS Independent
• Motherboard ROM BIOS
• Adapter card ROM BIOS extensions
• Master (partition) boot record (MBR)
• Volume boot record (VBR)
OS Dependent
• System files
• Device drivers
• Programs run at startup
The first portion of the startup sequence is
operating system independent
, which means
thesestepsarethesameforallPCsnomatterwhichoperatingsystemisinstalled.Thelat-
ter portion of the boot sequence is
operating system dependent
, which means those steps
can vary depending on which operating system is installed or being loaded. The follow-
ingsections examine boththeoperating system-independent startup sequence andtheop-
erating system-dependent startup process for various operating systems. These sections
provideadetailed account ofmanyoftheerrormessages thatmightoccurduringtheboot
process.
The Hardware Boot Process: Operating System Independent
If you have a problem with your system during startup and can determine where in this
sequence of events your system has stalled, you know which events have occurred and
probably can eliminate each of them as a cause of the problem. The following steps occur
in a typical system startup regardless of which operating system you are loading:
1.
You switch on electrical power to the system.
2.
The power supply performs a self-test (known as the POST). When all voltages and
current levels are acceptable, the supply indicates that the power is stable and sends
