Acronis os selector 8.0 User Manual
1.6
How does Acronis OS Selector Function?
During the installation on your computer, Acronis OS Selector writes its own
code into the MBR of the first hard disk, and thus gains control before any
other operation system. The old MBR content is stored in the \BOOTWIZ\
MBRBACKS.DAT file to enable a restore of the configuration as it was before
Acronis OS Selector installation. Acronis OS Selector MBR contains the
information about what hard disk and partition holds the main part of the
boot manager. With help from this information, the MBR code loads the
Acronis OS Selector boot sector (it is located in the
\BOOTWIZ\BOOTSECT.SYS file) and passes control to it. In turn, this boot
sector code looks for the BOOTWIZ.SYS (Acronis OS Selector Loader) file in
the root folder and loads it. The loader checks if any changes were done to
the partition structure and boot sectors since the last execution. If there are
any changes then \BOOTWIZ\ BOOTCFG.EXE (Acronis OS Selector Setup) is
automatically executed. It then tracks the changes and tries to find any new
operating systems with their help. The configurations of the newly found
operating systems are automatically added to the Boot Menu configurations.
The \BOOTWIZ\ BOOTMENU.EXE program is then executed. This is the
Acronis OS Selector Boot Menu itself.
code into the MBR of the first hard disk, and thus gains control before any
other operation system. The old MBR content is stored in the \BOOTWIZ\
MBRBACKS.DAT file to enable a restore of the configuration as it was before
Acronis OS Selector installation. Acronis OS Selector MBR contains the
information about what hard disk and partition holds the main part of the
boot manager. With help from this information, the MBR code loads the
Acronis OS Selector boot sector (it is located in the
\BOOTWIZ\BOOTSECT.SYS file) and passes control to it. In turn, this boot
sector code looks for the BOOTWIZ.SYS (Acronis OS Selector Loader) file in
the root folder and loads it. The loader checks if any changes were done to
the partition structure and boot sectors since the last execution. If there are
any changes then \BOOTWIZ\ BOOTCFG.EXE (Acronis OS Selector Setup) is
automatically executed. It then tracks the changes and tries to find any new
operating systems with their help. The configurations of the newly found
operating systems are automatically added to the Boot Menu configurations.
The \BOOTWIZ\ BOOTMENU.EXE program is then executed. This is the
Acronis OS Selector Boot Menu itself.
The Boot Menu allows you to choose which operating system to boot. The
boot manager itself performs all the actions that are necessary for the
preparation of boot context for the selected operating system and passes
control to its boot sector. Then the operating system is booted normally
without any help from Acronis OS Selector.
boot manager itself performs all the actions that are necessary for the
preparation of boot context for the selected operating system and passes
control to its boot sector. Then the operating system is booted normally
without any help from Acronis OS Selector.
1.7
What is a Boot Context?
Every operating system configuration that was detected by Acronis OS
Selector has its own boot context that includes the following elements:
Selector has its own boot context that includes the following elements:
• Operating system partition (operating system boot partition, partition of
system files). Such partitions are marked with a «Boot» flag in Acronis OS
Selector Setup interface.
Selector Setup interface.
• Boot sector of an operating system (for operating systems installed on
FAT partitions). Operating system is booted by loading it to memory
address 0000h:7C00h and executing it.
address 0000h:7C00h and executing it.
• Boot sector modifiers. Some modification of the boot sector data is
needed to allow certain operating systems to be booted from a logical
partition and/or from non-first hard disk. Acronis OS Selector allows
modification of the following parameters: BIOS extension usage for
MS-DOS 7.1/8.0 (Windows 95OSR2/98/ME), hard disk number, absolute
boot sector number, or boot partition letter for OS/2.
partition and/or from non-first hard disk. Acronis OS Selector allows
modification of the following parameters: BIOS extension usage for
MS-DOS 7.1/8.0 (Windows 95OSR2/98/ME), hard disk number, absolute
boot sector number, or boot partition letter for OS/2.
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