Smart Use of "DEBUG" to Easily Clear CMOS Password - China DOS Union Forum

If you forget the password to enter the CMOS setup program, in addition to the method of using jumper shorting on the motherboard to clear it, you can also use the software clearing method. The following will introduce how to clear the CMOS password under DOS.

In DOS, there is an editor, which is DEBUG. It is a very practical tool. The startup method is to enter the command DEBUG at the DOS command prompt, and then you can enter the DEBUG editing interface.

After entering the command in the command prompt state, restart the computer to clear the CMOS password. The following are five command lines to clear the CMOS password.

Method one
-o 70 16
-o 71 16
-q
Method two
-o 70 11
-o 71 ff
-q
Method three
-o 70 10
-o 71 10
-q
Method four
-o 70 23
-o 71 34
-q
Method five
o 70 10
-o 71 ff
-q

We used the two numbers 70 and 71 in methods one, two, three, four, and five (as shown in Table 1) because the data access in CMOS is implemented through these two I/O ports 70 and 71. Port 70H is a byte address port, used to set the address of data in CMOS, and port 71H is used to read and write the content of the data unit in the CMOS address set by port 70H.

In addition to the DEBUG method introduced earlier, some tool software can also be used to clear, such as Pctools 5.0, Biospwds.exe and Comspwd.exe, etc. Here they will not be introduced one by one.

c>debug
-o70 11
-o71 14
-q
c>

[ Last edited by defrag on 2005-7-21 at 14:09 ]

I have a method, but I cleared the CMOS settings
o 70 e
o 71 0

There is no command line when starting up in WINXP. And when entering from the safe mode with command line, you also need to enter the password. Then, may I ask how everyone finds the command line before entering the password. Thanks~~

Originally posted by lanyu008 at 2005-12-12 01:11 AM:
There is no command line when booting in WINXP.
And when entering from the safe mode with command line, you also need to enter the password. Then, may I ask everyone how to find the command line before entering the password. Thanks~~

Also want to know!

Boot from a 98 boot disk or a DOS boot disk to enter the DOS interface. Because it's a CMOS password, it has nothing to do with the system you're using.

If the hard disk was originally set as the first boot device, and you want to boot from a floppy disk or CD-ROM without entering a password (or clearing the CMOS password) to change the BIOS settings, how to do it?

The notebook is invalid!

Floor1　ko20010214	Posted 2002-11-06 00:00
版主　Posts 1,628　Credits 7,296
If you forget the password to enter the CMOS setup program, in addition to the method of using jumper shorting on the motherboard to clear it, you can also use the software clearing method. The following will introduce how to clear the CMOS password under DOS. In DOS, there is an editor, which is DEBUG. It is a very practical tool. The startup method is to enter the command DEBUG at the DOS command prompt, and then you can enter the DEBUG editing interface. After entering the command in the command prompt state, restart the computer to clear the CMOS password. The following are five command lines to clear the CMOS password. Method one -o 70 16 -o 71 16 -q Method two -o 70 11 -o 71 ff -q Method three -o 70 10 -o 71 10 -q Method four -o 70 23 -o 71 34 -q Method five o 70 10 -o 71 ff -q We used the two numbers 70 and 71 in methods one, two, three, four, and five (as shown in Table 1) because the data access in CMOS is implemented through these two I/O ports 70 and 71. Port 70H is a byte address port, used to set the address of data in CMOS, and port 71H is used to read and write the content of the data unit in the CMOS address set by port 70H. In addition to the DEBUG method introduced earlier, some tool software can also be used to clear, such as Pctools 5.0, Biospwds.exe and Comspwd.exe, etc. Here they will not be introduced one by one.

Floor2　defrag	Posted 2005-07-21 14:07
中级用户　Posts 570　Credits 456
c>debug -o70 11 -o71 14 -q c> [ Last edited by defrag on 2005-7-21 at 14:09 ]

Floor3　brglng	Posted 2005-07-23 18:32
银牌会员　Posts 466　Credits 1,200　From 上海
I have a method, but I cleared the CMOS settings o 70 e o 71 0

Floor4　lanyu008	Posted 2005-12-12 01:11
新手上路　Posts 7　Credits 13　From 广西柳州
There is no command line when starting up in WINXP. And when entering from the safe mode with command line, you also need to enter the password. Then, may I ask how everyone finds the command line before entering the password. Thanks~~

Floor5　wbhing	Posted 2005-12-12 15:43
新手上路　Posts 3　Credits 6
Learn, learn~~~~

Floor6　hzy	Posted 2005-12-12 23:09
高级用户　Posts 135　Credits 578
Originally posted by lanyu008 at 2005-12-12 01:11 AM: There is no command line when booting in WINXP. And when entering from the safe mode with command line, you also need to enter the password. Then, may I ask everyone how to find the command line before entering the password. Thanks~~ Also want to know!

Floor7　wphs0326	Posted 2005-12-16 15:29
银牌会员　Posts 509　Credits 1,708　From 安徽淮南
Boot from a 98 boot disk or a DOS boot disk to enter the DOS interface. Because it's a CMOS password, it has nothing to do with the system you're using.

Floor8　hzy	Posted 2005-12-17 00:02
高级用户　Posts 135　Credits 578
If the hard disk was originally set as the first boot device, and you want to boot from a floppy disk or CD-ROM without entering a password (or clearing the CMOS password) to change the BIOS settings, how to do it?

Floor9　ofaith	Posted 2005-12-18 20:40
新手上路　Posts 5　Credits 10
The notebook is invalid!

Floor10　scandisk	Posted 2005-12-20 09:37
初级用户　Posts 11　Credits 20
Bump, learning