MCSE : Security Specialist
Identify the basic system boot sequences and boot methods,
including the steps to create an emergency boot disk with utilities
installed for Windows 9x, Windows NT, and Windows 2000.
Startup Process Windows 95/98
ROM
BIOS Bootstrap Process
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POST Power On Self Test routines are run.
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The master boot record and partition table are read.
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The Plug and Play BIOS checks nonvolatile random access memory
(RAM) for input/output (I/O) port addresses, interrupt request
lines (IRQs), direct memory access (DMA) channels, and other
settings needed to configure Plug and Play devices on the
computer.
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All Plug and Play devices found by the Plug and Play BIOS are
disabled.
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A map of used and unused resources is created.
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The Plug and Play devices are configured and re-enabled, one at
a time.
If
your computer does not have a Plug and Play BIOS, Plug and Play
devices are initialized using their default settings when you start
your computer.
Master Boot Record and Boot Sector
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The master boot record (MBR) locates the boot partition by
reading the partition table located at the end of the master
boot record.
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The MBR then passes control to the boot sector in that
partition, which contains the disk boot program.
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The boot sector copies the Io.sys file from the root directory
into memory.
Io.sys File
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Minifile allocation table (FAT) file system is loaded.
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Msdos.sys file is read.
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Starting Windows 95 message is displayed.
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If you have multiple hardware profiles in Windows 95, you must
choose a hardware configuration to use now.
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Logo.sys file is loaded and displays a startup image on the
screen.
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If the Drvspace.ini or Dblspace.ini file exists, the
Drvspace.bin or Dblspace.bin file is loaded into memory.
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Io.sys file checks the system registry files.
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Io.sys file opens the System.dat file.
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The Dblbuff.sys file is loaded if double buffering is enabled.
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If you have multiple hardware profiles in Windows 95, the
hardware profile you selected earlier is loaded from the
registry.
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Io.sys file processes the Config.sys file.
Real-Mode Configuration
Some
hardware devices and programs require that drivers or files be
loaded in real-mode in order for them to work properly. Config and
Autoexec are only need for backward compatibility.
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Config.sys file loads drivers into memory. If the Config.sys
file does not exist, the Io.sys file loads the following
required drivers: Ifshlp.sys, Himem.sys, and Setver.exe
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Windows 95 reserves all global upper memory blocks (UMBs) for
Windows 95 operating system use or for expanded memory support
(EMS).
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Autoexec.bat file loads files and terminate and stay resident
(TSR) programs into memory.
Win.com File and the Windows 95 Environment
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Win.com file is run.
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Win.com file accesses the Vmm32.vxd file and loads into memory.
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The real-mode virtual device driver loader checks for duplicate
virtual device drivers (VxDs) in the Windows\System\Vmm32 folder
and the Vmm32.vxd file. If a VxD exists in both the
Windows\System\Vmm32 folder and the Vmm32.vxd file, the
duplicate VxD is "marked" in the Vmm32.vxd file so that it is
not loaded.
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The real-mode virtual device driver loader checks that all
required VxDs loaded successfully. If not, it attempts to load
the drivers again.
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Once the real-mode virtual device driver loading is logged,
driver initialization occurs. If there are any VxDs that require
real-mode initialization, they begin their process in real-mode.
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Vmm32 switches the computer's processor from real-mode to
protected- mode.
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VxD initialization process occurs.
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After all the static VxDs are loaded, the Krnl32.dll, Gdi.exe,
User.exe, and Explorer.exe files are loaded.
Network Environment and Multi-User Profiles
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The network environment is loaded.
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User is prompted to log on to the network
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Programs in the Startup group and the RunOnce registry key are
run.
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After each program in the RunOnce registry key is started, the
program is removed from the key.
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