Where would be the best place to switch to PMODE?
The kernel itself? If you do switch to pmode in kernel
I am confused because the kernel persumably would have been written to run PMODE.
Is this right or am I just a fool?
Would I be right in thinking that NASM produces PMODE
files?
Also could some one lease describe what is the difference
between a bootloader and boot strap???
Forgive me if these questions sound stupid but everyone has to start somewhere.
Chris.
Switching to protected mode?
-
Chris Giese
RE:Switching to protected mode?
>On 2001-03-25 07:29:37, Chris Tomlinson wrote:
>Where would be the best place to switch to PMODE?
>The kernel itself?
Maybe the second-stage bootloader. GRUB will
switch to pmode before jumping to the kernel; so
will Alexei Frounze's loader. There are some
problems mixing 16- and 32-bit code in one
executable file.
>Would I be right in thinking that NASM produces PMODE
>files?
NASM will make 16-bit real mode code or 32-bit
pmode code.
>Also could some one lease describe what is the difference
>between a bootloader and boot strap???
I don't see an obvious difference between these
two terms.
--
geezer@ | pmode tutorial, homebrew OS:
execpc.com | http://www.execpc.com/~geezer/os
>Where would be the best place to switch to PMODE?
>The kernel itself?
Maybe the second-stage bootloader. GRUB will
switch to pmode before jumping to the kernel; so
will Alexei Frounze's loader. There are some
problems mixing 16- and 32-bit code in one
executable file.
>Would I be right in thinking that NASM produces PMODE
>files?
NASM will make 16-bit real mode code or 32-bit
pmode code.
>Also could some one lease describe what is the difference
>between a bootloader and boot strap???
I don't see an obvious difference between these
two terms.
--
geezer@ | pmode tutorial, homebrew OS:
execpc.com | http://www.execpc.com/~geezer/os
-
Schol-R-LEA
RE:Switching to protected mode?
>On 2001-03-25 07:29:37, Chris Tomlinson wrote:
>Also could some one lease describe what is the difference
>between a bootloader and boot strap???
They are the same thing. The full, original term
was 'bootstrap loader', which comes from the old
expression of 'pulling yourself up by your
bootstraps' - that is to say, to start off with
no visible means of support. A bootstrap loader
does something normally impossible - starts
running software when no software is there to be
run - because it cheats a bit - the software that
is running is a hardwired part of the ROM BIOS.
Older systems had various other hacks to let the
system load a program when the hardware started -
for example, some PDP-8s (IRRC) started up a
paper tape reader automatically, and many early
computers had toggles switches with which you'd
enter the bootstrap software manually, and the
processor only started after you hit a Go button.
One of the reasons ferrite-core memories were
such a success in the 1960s was because they were
persistent - as long as nothing had caused it
to clear itself, the system code would still be
ready to run when the computer was turned on.
>Also could some one lease describe what is the difference
>between a bootloader and boot strap???
They are the same thing. The full, original term
was 'bootstrap loader', which comes from the old
expression of 'pulling yourself up by your
bootstraps' - that is to say, to start off with
no visible means of support. A bootstrap loader
does something normally impossible - starts
running software when no software is there to be
run - because it cheats a bit - the software that
is running is a hardwired part of the ROM BIOS.
Older systems had various other hacks to let the
system load a program when the hardware started -
for example, some PDP-8s (IRRC) started up a
paper tape reader automatically, and many early
computers had toggles switches with which you'd
enter the bootstrap software manually, and the
processor only started after you hit a Go button.
One of the reasons ferrite-core memories were
such a success in the 1960s was because they were
persistent - as long as nothing had caused it
to clear itself, the system code would still be
ready to run when the computer was turned on.