System Administration with msdos 6.0 Sachverstand2 @ Geocities.com, 01.01.1998

Computer boot on msdos 6

As the os is the brain of the computer, it needs to know what the computer is constructed of. The RAM size is read from the BIOS (Basic Input/Output System; sits in readonly-chips on the motherboard).
Then, the computer wants to know which os to boot, that is from which device it shall read its kernel. BIOS tells him, 'cause BOIS has a CMOS memory to know.
Then, computer reads and executes the first track of the first sector of this drive. This is usually a program that loads the kernel into computer's memory.
Now, computer knows that he is. But what is it?

All else hardware must be read from the bootup files:

• config.sys
• autoexec.bat
• msdos.sys
• io.sys

A typical config.sys

   REM this is a comment. it may be left off with no effect on the computer.
DEVICE=C:\aaawin31\DOS\HIMEM.SYS /testmem:off
   REM this line starts a driver (*.sys) for a certain hardware. In this case, the 
   REM "added" hardware is RAM exceeding 640 kB. 
DEVICE=C:\aaawin31\DOS\EMM386.EXE NOEMS
   REM this line starts a program (*.exe) that copies memory contents from 
   REM over 640kB into 640kB. Only here command.com can find and process 
   REM memory contents.
device=c:\aaawin31\dos\toshv212.sys /d:quadsped
   REM another device. The driver is toshv212.sys, and its name is quadsped.
   REM obviously a cd-rom.
BUFFERS=40,0
   REM buffers for input and output. memory use may be neglected.
FILES=40
   REM maximal number of files which may be open at the same time. command.com
   REM needs 
DOS=UMB
   REM dos is loaded in memory between 640kB and 1MB to save memory 
   REM beneath 640kB.
LASTDRIVE=L
   REM drives are named A:, B:, and so on. 
FCBS=4,0
   REM maybe to ensure compatibility to former dos's.
BREAK=ON
   REM means programs may be terminated with -c.
STACKS=9,256
   REM maybe to ensure compatibility to former dos's.

A typical AUTOEXEC.BAT

path=c:\dos;c:\windows;c:\internet
   REM if you are in c:\home\larry, and want to execute the command dir, 
   REM command.com will not find dir.exe in there. then it looks into the
   REM directories that are listed in the environment variable path.
subst h: c:\home\larry
   REM larry likes to type "h:" more than to type "cd \home\larry". h: 
   REM is a part of the c:-directory tree, that is, it looks as a tree, that
   REM is, it can simulate a standalone tree. 
   REM no one knows where the directory trees of msdos grow on. some
   REM say, they grom out of command.com. 
set comspec=c:\dos\command.com
   REM seems larry wants to boot from diskette and likes to swap diskettes 
   REM sometimes. so he passes the system to a copy of command.com.
h:
   REM larry doesn't even like to type "h:"
set midi=synth:1 map:e
   REM another environment variable.
cls
   REM cleans the screen and puits the cursor into the upper left corner.
virstop2
   REM a useful, fast program running in the background and scanning
   REM every swapped disk for viruses BEFORE they damage the system.
cls
LH /L:0;1,44432 /S C:\WINDOWS\SMARTDRV.EXE c+
   REM this line was made by memmaker.exe. it switches on the disk
   REM cache for drive c, in read&write mode, thus increasing disk
   REM speed visibly. 
   REM remember that c:\dos\smartdrv.exe won't work with windoze. 
   REM memmaker put this program into higher memory, thus freeing
   REM memory < 640kB. 
   REM load is for load, of course, lh is for loadhigh.
cls
set temp=c:\temp
set dircmd=/Ogne /p
   REM larry wishes dir to present his files in the following /Order: 
   REM  o directories first
   REM  o sorted by _n_ame
   REM  o sorted by _e_xtension
   REM  o _p_age after page.
cls
keyb gr
   REM larry owns a german keyboard.
cls
mouse /Y
   REM larry owns a mouse. 
   REM if you want to know what /Y is, rtfm by typing
   REM help mouse
cls
doskey
   REM As standard in un*x, larry wants to recall things he typed in
   REM before, by pressing 
cls
c:\dos\mscdex /d:quadsped
   REM another program, connecting the cdrom to command.com
   REM and using memory < 640kB.
prompt $p $d $t$_$g
   REM larry isn't satisfied by a prompt like
   REM h:>
   REM He likes a more opulent thing, that looks like
   REM h:\larry\texts 01.04.1995 10:38
   REM >
@echo off
   REM remember the "cls" "doskey" above? this means that the word
   REM doskey will displayed in the upper left corner of the screen. 
   REM larry doesn't like this now, so he switches this eco off. 
   REM he doesn't even want to see the command "echo off" so he
   REM types "@echo off"
cls
ver
echo.
   REM while "echo ." prints a line with a ".", "echo." prints an empty line
echo.
echo                                  Hallo User,
echo.
echo                        Quake wird mit "quak" gestartet.
echo.
echo.
echo.
echo.
   REM There may be another user on the system, sometimes, who enjoys
   REM "quake" by id. He is prompted with half a screeenful instruction how
   REM to start it. 

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