Clear CMOS all Tricks
Debug has been included in every version of MS-DOS as well as Windows.
When running any of the debug routines it is recommended that if you have
Windows that you exit or shut down to get into a real DOS prompt (unless
you're running Windows ME, Windows 2000, Windows XP, or later versions).
Once at the MS- DOS prompt, run through the below example, this example
is perfectly fine to run on any PC Computer running MS-DOS / Windows and
will not harm anything.
Type debug and press enter.
This should get you to a - (small dash). This is the debug prompt.
At the - type d40:00 and press enter; this will return several lines of
After the feedback you will be back to the debug prompt.
To exit out of debug type q and press enter. This will return you back to
the MS-DOS prompt.
In some of the below debug routines you will notice that a "g" is typed,
then "q". G tells the computer that the code type is not self executing
and must be run at this point. If completed, the program will return
Program Terminated Normally which indicates you can now quit from the
debug program. TESTING PORTS
The below debug routine will check the ports of the computer to allow you
to know if ports are being detected or not. Type debug to get to the "-"
You should get several lines; however, the first line is the only
important line, which should read the following:
0040:0000 F8 03 F8 02 E8 03 E8 02 - 78 03 78 02 BC 03
The above graph shows you what the feed back means as far as port, so if
you see F8 03, this would be an indication that COM1 is being detected;
if you see 00 00, this is an indication that it is not being detected,
which could mean that hardware is bad or that it is disabled inCMOS
Once you have finished looking at the information, type Q and press enter
to get out of Debug.
The below debug routine will clear CMOS, BIOS, Passwords, Settings,
Viruses, and other items residing in the CMOS. During this process you
may get returned characters which are an indication that the string has
gone in, if you by chance get ERROR ensure that you have typed the line
in correctly, if not retype. Ensure that you do not skip any lines, that
it is ALL typed in correctly to help prevent problems. Before running
this Debug routine also ensure that you have read the above disclaimer.
After typing debug you will get "-" which is were you can begin by typing
A and pressing enter. A <ENTER>
MOV AX,0 <ENTER>
MOV AX,CX <ENTER>
OUT 70,AL <ENTER>
MOV AX,0 <ENTER>
OUT 71,AL <ENTER>
INC CX <ENTER>
CMP CX,100 <ENTER>
JB 103 <ENTER>
INT 20 <ENTER>
<ENTER> Note: Nothing is typed on this line
G <ENTER> By pressing G this will execute the above script, ensure you
have read and agree to the above disclaimer.
Q <ENTER> Then reboot and you will get a Setup Checksum Error. Go into
setup, correct all the incorrect values, time, date...
This test will test to see if your Joystick is present or not. Type debug
from the DOS prompt once at the "-". Type i201 If you get a FF response
attempt hold one of the main buttons on your joystick, and while holding
the button down type i201 and see if a different response is given, each
button on the joystick should return a different response. However, some
special joysticks, such as the Microsoft Sidewinder, which has more than
4-5 buttons, may not return a response for all extra buttons because
these buttons are generally controlled through software. If a FF is still
given on each of the buttons on the game paddle or joystick, it is a good
possibility that either the Joystick and or the Joystick port is bad. If
possible, attempt these steps with another known working joystick.
However, if you are receiving different responses when pressing and
holding the keys on the joystick, the computer hardware is working
properly. Type q and press enter to quit out of debug.
ERASING SECTOR 2
Before doing the below routine ensure that you have read our disclaimer
and that you're sure that this is safe to do on your hard drive. Some
computer hard drive manufacturers may void your warranty if this routine
is ran or in some situations this can cause damage to the hard drive.
This routine is useful in clearing DDO and unknown partitions. If this
routine completes successfully it will erase everything in Sector 2. In
the below debug routine, only type what is in bold from line 3 to 9, you
will get a response if typed in properly. If you get a response continue
to type the bold text as shown below in the below example.
-FCS:200 400 0<enter>
-xxxx:0100 mov ax,302<enter>
-xxxx:0103 mov bx,200<enter>
-xxxx:0106 mov cx,2<enter>
-xxxx:0109 mov dx, 80<enter>
-xxxx:010a int 13<enter>
-xxxx:010c int 20<enter>
-xxxx:0110 <enter>(without typing anything)
Program terminated normally.
ERASE ALL HDD INFORMATION
This debug routine is used to erase all partition information on the hard
disk drive and is only recommend for experienced users or users who are
unable to delete the partition information through fdisk. In the below
debug routine, only type what is in bold from line 3 to 8, you will get a
response if typed in properly. If you get a response continue to type the
bold text as shown below in the below example. A:\>debug <enter>
-F 200 L1000 0 <enter>
-A CS:100 <enter>
xxxx:0100 MOV AX,301 <enter>
xxxx:0103 MOV BX,200 <enter>
xxxx:0106 MOV CX,1 <enter>
xxxx:0109 MOV DX,80 <enter> (80 for hd 0 or 81 for hd 1 ) xxxx:010C INT
xxxx:010E INT 20 <enter>
Program terminated normally
-q<enter> Once this debug routine is complete, reboot computer and all
partitions should be erased. Before anything can be installed back onto
the computer you must run Fdisk and recreate the partition as well as
format the hard disk drive.
ERASE HDD AND CLEAR CMOS
Before doing the below routine ensure that you read our disclaimer as
well as are sure that this is safe to do on your hard drive. Some
computer hard drive manufacturers may void your warranty or this may
cause damage to the hard drive when doing the below example. This routine
is useful in clearing DDO and removing possible viruses. If this routine
completes successfully it will erase everything from your Hard Drive as
well as your reset your CMOS values. In the below debug routine, only
type what is in bold from line 3 to 17, you will get a response if typed
in properly. If you get a response continue to type the bold text as
shown below in the below example.
-fcs:200 400 0 <enter>
-xxxx:0100 mov ax, 0 <enter>
-xxxx:0103 mov ax, cx <enter>
-xxxx:0105 out 70, al <enter>
-xxxx:0107 mov ax, 0 <enter>
-xxxx:010a out 71,al <enter>
-xxxx:010c inc cx <enter>
-xxxx:010d cmp cx,100 <enter>
-xxxx:0111 jb 103 <enter>
-xxxx:0113 mov ax,302 <enter>
-xxxx:0116 mov bx,200 <enter>
-xxxx:0119 mov cx,1 <enter>
-xxxx:011c mov dx,80 <enter>
-xxxx:011f int 13 <enter>
-xxxx:012l int 20 <enter>
-xxxx:0123 <enter> (without typing anything.)
-g <enter> program terminated normally
If you are doing this debug routine to clear out a possible virus turn
off your computer and wait and turn back on.
Once back at DOS, reboot your computer When your computer comes back on
from doing the above you will get an error message as booting up the
computer, such as "Invalid Configuration". You must enter CMOS and set
the time and date, save, and reboot again. Once rebooted, you will then
need to run fdisk and recreate the partitions. Once created, you will
then need to format the hard drive and proceed as normal.
DISCHARGE OLD LAPTOP BATTERIES
The below debug routine is used for older laptop batteries (i.e.
batteries made from 1990-1992), we do not recommend using this routine on
any newer laptop batteries or any NiMH batteries N DPDISCHG.COM <Enter>
MOV DX,01E8 <Enter>
MOV AL,F9 <Enter>
OUT DX,AL <Enter>
INT 20 <Enter>
Q <Enter> This will write dpdischg.com to the current directory. To run
this utility type dpdischg.
REBOOT YOUR COMPUTER
Implement this debug routine to reboot your computer. DEBUG E 40:72 34 12
G To create a batch file that reboots your computer without having to
type the above command each time, use the below example. GOTO BEGIN
E 40:72 34 12
DEBUG < REBOOT.BAT
CREATE A SLEEP FILE
This file allows your computer to sleep for a specified amount of time.
This file is not dangerous in any way; if typed improperly, more than
likely the file will just not work. Type Debug You should get a "-" begin
typing the below information; after each line you may get a response, do
not press enter and type the next line after the response. N SLEEP.COM
DB "XX SECONDS", D, 24
DB " ", D, A, 24 RCX
Q Tip: You may cut and paste the above test into a notepad document and
save the file with a .scr extension. Once saved from DOS, type debug <
name of scrSLEEP.COM. which should create the file; should be created
CHECK BIOS DATE
The below debug routine is to check the date of your BIOS. All BIOS dates
on PC compatible computers is stored at memory address FFFF5h. To display
the date of your BIOS do the following: At the C:\> type debug - d FFFF:5
L 8 After typing the above command you should receive a string similar
to: FFFF:0000 30 34 2F-33 30 2F 39 38 4/30/98 The 4/30/98 would be the
date of your computer BIOS.
VIDEO CARD TYPE
The below debug routine will list the type of video card within your
computer. This is an excellent way of determining the chipset on the card
or the card within your computer without opening the computer. At the
C:\> type debug -d c000:0040 After typing the above command you should
receive several lines of text similar to: C000:0040
.[STB nVIDIA TNT
ver. 1.10 ....C
STB Systems Inc.
As you can pick out in the above dump, this gives you enough information
to determine the make and the year made on the video card. On line 4 you
can see the make of this video card, which in this case is a N VIDIA TNT
which would be the Riva TNT chipset. The next line you notice the version
of the card and finally the line thereafter is the copyright or the year
manufactured, generally. If you are unable to capture any information
which sounds like the video card, you can also type -d c000:0090