$WW,1$$FG,5$$TX+CX,"Booting A PC"$$FG$

TempleOS only supports traditional $FG,2$BIOS$FG$ booting, not the newer technique, $FG,2$UEFI$FG$.  This describes $FG,2$BIOS$FG$ booting.

When you turn-on (better term is "power-up"!) a computer or do a hardware reset, it starts in the $FG,2$BIOS$FG$.  Sometimes, you must change the $FG,2$BIOS$FG$ boot order to boot stuff.

The $FG,2$BIOS$FG$ loads a boot sector from CD/DVD or hard disk or whatever.  The boot sector runs in 16-bit mode and often loads-in a second file that's bigger if it can't be done by just one sector.  It's a safe bet that boot sectors are hand-coded assembly language  Most boot sectors use the $FG,2$BIOS$FG$ to load-in the rest.

Not only do boot sectors have a size limit, 512 bytes or 2048 bytes for CD/DVD, the files they load have to fit within 640K because they run in 16-bit mode.  This means they usually can't just load the whole operating system and start it running.  I guess some boot loaders, like $LK,"Grub",A="FI:::/Doc/Grub.TXT"$, have a capability of switching modes before handing-off control to the operating system.  Anyway, the operating system must load the rest of itself.  My $LK,"Kernel",A="FI:::/Kernel/KStart.CPP"$ module is what the boot sector loads and I try to put a minimum in it so that it will always fit in 640K.  It switches to 32-bit mode, then, to 64-bit mode allowing access to more memory.  It loads in the rest of TempleOS.

All the boot related stuff for TempleOS is in the $FG,2$/Adam/Opt/Boot$FG$ directory.

$LK,"Boot.CPP",A="FI:::/Adam/Opt/Boot/BootIns.CPP"$	Installs and patches boot sectors
$LK,"BootDVD.CPP",A="FI:::/Adam/Opt/Boot/BootDVD.CPP"$	CD/DVD Boot sector
$LK,"BootMHD.CPP",A="FI:::/Adam/Opt/Boot/BootMHD.CPP"$	Master HD boot record
$LK,"BootMHD2.CPP",A="FI:::/Adam/Opt/Boot/BootMHD2.CPP"$	Stage 2 master boot loader
$LK,"BootHD.CPP",A="FI:::/Adam/Opt/Boot/BootHD.CPP"$	HD partition boot record

$FG,2$BootDVD$FG$ is the CD/DVD boot sector.  If you are curious on the layout of $FG,2$ISO9660$FG$ CD/DVDs, see $LK,"DiskCDDVD.CPP",A="FI:::/Adam/Opt/Boot/DskISOFile.CPP"$.  To make a custom bootable CD/DVD, look here $LK,"Bootable CD",A="FI:::/Misc/DoDistro.CPP"$.

$FG,2$BootMHD$FG$ is the master boot record for a hard drive.  This goes on block zero.  It loads-in $FG,2$BootMHD2$FG$ which is stored as a file on a partition, kinda risky and unusual -- most other master boot loaders place stage 2 in a gap that's not in any particular partition.   $FG,2$BootMHD2$FG$ displays a menu and will boot a partition.  Each partition has it's own partition boot record, the first block of the partition.  $FG,2$BootHD$FG$ is the boot record for a TempleOS partition.

My boot records don't access directories because that would make them too big for one block and would make them depend on a file system layout.  Instead, they get patched with the LBA, logical block addresses, to load other stuff.  To update with a new TempleOS kernel, you must create a binary file and patch the boot loader so it knows the LBA blocks to load.  Therefore, you usually recompile the kernel and update the boot sector at the same time.  $LK,"MakeOSDrvBootInstall",A="MN:MakeOSDrvBootInstall"$() does this.  $LK,"MasterBootIntall",A="MN:MasterBootIntall"$() will install a master boot loader.

With TempleOS , the $FG,2$Kernel$FG$ module loads the $FG,2$Compiler$FG$ module so it can process start-up scripts and works with source code from then on.  $LK,"::/StartOS.CPP"$ is the starting start-up script.  It processes (compiles into memory) the stuff in the $FG,2$/Adam$FG$ and $FG,2$/Home$FG$ directories.

It is possible to reboot without doing a hardware rst.  This is faster.  You might do this when working on $FG,2$Kernel$FG$ or your start-up scripts when you want them to take effect.  See $LK,"RAMReboot",A="MN:RAMReboot"$().

$SP,"",BI=1$









































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