Re: Linux syscalls

From: Jim Carlock (anonymous_at_127.0.0.1)
Date: 06/02/04 

Date: Wed, 02 Jun 2004 17:19:40 GMT

"Beth" wrote:
<snip>
Although, for example, it _MUST_ be true for opening a file in
NTFS or file mapping, as NTFS was never supported by DOS and
file mapping wasn't possible either...
</snip>

A device driver or a rewrite of DOS could permit this, no?
After all NTFS is JUST a file system, like FAT and if the
DOS interrupts are revectored...

I haven't gotten into Assembly and the whole boot up
procedure as much as I've wanted to... but I do know
the BIOS reads the first sector of the disk drive during
boot up to find a set of instructions there (and I don't
know what instruction set it currently knows, but I think
it konws the Intel Assembly instruction set, but as far as
predefined Interrupts go, I don't think there are any. Am
I correct in this statement ?

So obviously the BIOS has a limited set of (Interrupts ?)
commands that it uses to read the disk. Would anyone be
able to tell me where to find such information about the
internal (Interrupts ?) commands of the BIOS ?

After it reads the boot sector, the code for the internal
file system is loaded (Interrupts ?), and the limited set of
code for the hardware (monitor, disk drives) is loaded.

Then it can go about displaying information via some
internal commands (Interrupts ?) to the screen, reading
the appropriate file to be loaded (in MSDOS, the first
file was IO.SYS, then MSDOS.SYS, and then the
last OS file was COMMAND.COM, and then device
drivers and programs and applets were loaded from
config.sys and autoexec.bat).

Windows 3.1 and Windows 9x continued along that
precedent above but Win9x didn't need to have the
Win.com typed out inside the autoexec.bat file.
Win9x started loading win.com via the command.com
file I think. Am I correct ?

When Win9x gets loaded, a lot more files are read.

I don't know about how NT loads itself. I think it loads the
ntldr file, then runs the NTDETECT.COM program finally.

"Beth" wrote:
<snip>
DOS never used device drivers either...
</snip>

I'm not sure what that means. My understanding of DOS
using device drivers means the device driver is loaded
by being placed inside of the config.sys or the autoexec.bat.
Most device drivers in fact were loaded up inside of the
config.sys, but that means everyone has to conform to the
DOS disk reading rules and this is still true.

Even Win2K does not support UDMA and the device
drivers need to be loaded via a separate diskette.

I think you must have a different definition of a device
driver... Windows XP has many more extra device drivers
included with it. In fact I think the device drivers, the help
files and the extra programs take up at least half of the
file space for the operating system when the OS is installed.
In fact XP backups about 500 MB of operating system
files (the DLLCACHE folder). In fact my DLLCACHE
folder currently 944,000 KB of backups. Win2K is very
much similar. 

-- 
Jim Carlock
http://www.microcosmotalk.com/
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