1. Repair of non-physical 0 track bad floppy disk
This damage does not show any obvious scratches or mold from the floppy disk surface. Generally, the data can be recovered, but the floppy disk is reusing it.
The processing method is as follows:
Ⅰ. Enter debug
Ⅱ. Take a good disk that is not damaged in the boot area and insert it into the floppy drive.
-L 100 0 0 1
Ⅲ. Insert a damaged disk to the floppy drive
-W 100 0 0 1
-Q
Note: The capacity of good and bad disks must be the same
2. Physical 0 track bad data in floppy disk
For disks with 0 track damaged, they should generally be discarded. You might as well try the following method:
Magnetization treatment: Use a strong magnet to move repeatedly near the surface of the bad disk. Do not touch the disk medium to avoid scratching the surface, and then try formatting.
Floppy disk face replacement: Carefully open the disk, separate the solid magnetic chip from the metal chip, and then stick it together according to the original method and reformat it.
Diskfix: I believe everyone has used diskfix more, and the disk repair function inside is very useful. Can fix most disk surface errors.
3. Hard disk startup failure handling
Format a floppy disk on a normal machine, no other data
Enter debug
-L 0 2 0 1
-W 0 0 0 1
-Q
After starting the faulty machine with the system disk
Entering debug
-L 0 0 0 1
-w 0 2 0 1
-Q
4. Solution to the floppy disk not being read correctly
If using a floppy disk, the following prompt appears
General failure error reading drive A
It can be solved by the following methods:
Insert a good disk into the floppy drive
Enter debug
-A 100
****：*100 MOV AL,0
****：**** MOV CX,1
****：**** MOV DX,0
****：**** MOV BX,1000
****：**** INT 25
****：**** INT 20
Enter
-G=0100
Insert the bad disk and enter Debug
-A 200
****：*100 MOV AL,1
****：**** MOV CX,1
****：**** MOV DX,0
****：**** MOV BX,1000
****：**** INT 26
****：**** INT 20
Enter
-G=200
Save and restore data
The address of the 'address port' of CMOSRAM is 70H The address of the 'data port' is 71H When reading, you only need to send the read CMOSRAM address to 70H, and then you can get the required data from 71H.
(1) Read CMOS data and enter Debug
-A 100
****：*100 MOV BX,1000
****：**** MOV CX,0040
****：**** MOV AX,0000
****：0109 MOV DX,CX
****：**** MOV CX,0005
****：010E LOOP 010E
****：**** OUT 70,AL
****：**** MOV CX,0005
****：0115 LOOP 0115
****：**** IN AL,71
****：**** MOV [BX],AL
****：**** CMP AH,0E
****：**** JB 0123
****：**** ADD AH,80
****：0123 INC AH
****：**** INC BX
****：**** MOV CX,DX
****：**** MOV AL,AH
****：**** LOOP 0109
****：**** MOV AH,3C
****：**** MOV DX,0150
****：**** MOV CX,0020
****：**** INT 21
****：**** MOV BX,AX
****：**** MOV DX,1000
****：**** MOV CX,0040
****：**** MOV AH,40
****：**** INT 21
****：**** MOV AH,4C
****：**** INT 21
-A 150
****：0150 DB "",0
****：0159
-R CX
CX 0000
：60
-N SAVE
-W
-Q
-W 100 2 0 1
-Q
(2) Recover CMOS data and enter Debug
-A 100
****：*100 MOV CX,0150
****：**** MOV AH,3D
****：**** MOV AL,00
****：**** INT 21
****：**** MOV DX,1000
****：**** MOV BX,AX
****：**** MOV CX,0040
****：**** MOV AH,3F
****：**** INT 21
****：**** MOV AX,0000
****：**** MOV BX,DX
****：**** MOV DX,CX
****：**** MOV CX,0005
****：**** LOOP 011F
****：**** MOV AL,AH
****：**** OUT 70,AL
****：**** MOV CX,0005
****：**** LOOP 0128
****：**** MOV AL,[BX]
****：**** OUT 71,AL
****：**** JB 0136
****：**** ADD AH,80
****：**** INC AH
****：**** INC BX
****：**** MOV CX,DX
****：**** LOOP 011A
****：**** MOV AX,0040
****：**** MOV DS,AX
****：**** MOV AX,1234
****：**** MOV [0072],AX
****：**** JMP FFFF:0000
-A 150
****：0150 DB "",0
****：0159
-R CX
CX 0000
：60
-N WRITE
-W
-Q
Save and restore the boot sector data
The DOS boot program is read to memory 0000:7C00 and starts executing.
Get a normal boot program
Enter Debug
-L 100 2 0 1
-N A:
-R CX
：200
-W
-Q
Load the bootloader
Enter Debug
-N A:
-L
-R CX
：200
-W 100 2 0 1
-Q
7. Save and restore data of the main boot sector of the hard disk
Read the main boot sector information when the hard disk is working normally
Note: This data cannot be restored when the partition changes
Save the main boot sector data into Debug
-A 100
MOV AX,0201
MOV BX,0110
MOV CX,0001
MOV DX,0080
INT 13
INT 3
-G=100
-E 102 3
-E 10E C3
-R BX
BX 0110
:0
-R CX
CX 0001
:210
-N A:
-W
-Q
Recover the main boot sector data: just run disk A
8. Backup and recovery of non-allocated tables of hard disks
Allocation table backup when the computer is running normally
Enter Debug
-L 100 2 0 1
-N A:
-R CX
：200
-W
recover
Enter Debug
-N A:
-L
-W 100 2 0 1
-Q
9. Hard disk protection card insider
For those who often use computers outside, once a computer maintenance staff sets up a hard disk protection card, it is particularly troublesome to do something by themselves. Do you want to block the hard disk protection card? You may use the following methods to learn from:
Enter Debug
-A 100
MOV AH,0
MOV DL,0
INT 13
-T
Keep pressing T to find CS=F000 and record the value of DS at this time, such as: 1234
-E E0：4C
34 12 00 F0
-Q
10. Use Debuf as low-level formatting of hard disk
Low-level formatting of hard disks is generally used to use DM, but Debug can also low-level formatting of hard disks
Enter Debug
-A 100
MOV AX,500
MOV BX,180
MOV CX,0
MOV DX,80
INT 13
INT 3
-E 180 0 0 0 2
-Q
11. Cold start and hot start
Use Debug to implement cold start and hot start programs in the system
Cold start:
-A 100
JMP FFFF:0
INT 20
-N A:
-R CX
：0007
-w
-Q
Hot start:
-A 100
MOV AX,0040
MOV DS,AX
MOV AX,1234
MOV SI,0072
MOV (SI),AX
JMP FFFF:0
-N A:
-R CX
：0014
-W
-Q
Internal command encryption
like encrypted dir
Use pctools or diskedit to find the file under C:
Edit this file
In PCTOOLS: F-----F1 Then find all 03 44 49 52 After finding it, press F5 to modify it to the value you want. For example: foo After that, only by entering foo can you list the file or file directory.
diskfix has a good interface and is almost the same as pctools.
Note: If it cannot be modified, unlock the file luck
Other command codes
type 04 54 59 50 45
cd 02 43 44
del 03 44 45 44
copy 04 43 49 50 59