Debug plays a very important role in the process of learning assembly and is an extremely important debugging tool, so it is necessary to learn it.
| command format | Function Description | |
| A | [address] | Enter assembly instructions |
| C | [range] start address | Compares the area specified by "Range" with the same size area specified by "Start Address" and displays the different units |
| D | [scope] | Displays the contents of memory cells within the specified range |
| E | Address Byte Value Table | Replace the contents of the memory cell starting at "address" with the value in the value table |
| F | Range Byte Value Table | fills the memory area with the specified table of byte values |
| G | [=start address][breakpoint address] | Execute from the starting point (or current location) and end at the end point |
| H | value 1 value 2 | Displays the sum and difference of two hexadecimal values |
| I | port address | Input from port |
| L | [address [drive letter sector number of sectors]] | read from disk |
| M | range address | transfer byte values in "range" to the unit starting at "address" |
| N | file identifier [file identifier...] | Specify the filename to prepare for reading/writing the file |
| O | port address byte value | output to port |
| P | [=address] [number of instructions] | Press the execution process, but do not enter a subroutine call or soft interrupt |
| Q | Exit DEBUG without saving the file being debugged | |
| R | [register name] | Display and modify register contents |
| S | Range Byte Value Table | Searches the specified table of byte values within the memory area. If found, display the starting address, otherwise, display nothing |
| T | [=address] [number of instructions] | Trace execution, execute several instructions from the starting point (or current location) |
| U | [scope] | Disassemble, display the assembly instructions corresponding to the machine code |
| W | [address [drive letter sector number of sectors]] | Write content to disk, (BX, CX) is the number of bytes written |
A few notes about the parameters:
1. Hex: The data entered or displayed in DEBUG are in hexadecimal form
2. Separation: Commands and parameters, parameters and parameters should be separated by spaces, commas or tabs, etc.
3. Address: The address is represented in the form of "segment value: offset", and segment register can also be used to represent "segment value",
such as: 1000:0, ds:10, es:200, cs:30, etc.
4. Range: Indicates the address range, it has two representation modes: "Address 1 Address 2" and "Address 1 Length".
Among them: "Address 1" indicates the starting address, which is expressed by "segment value: offset";
"Address 2" indicates the end address, which is only expressed by "offset";
"Length" is expressed by the letter 'L' number at the beginning.
For example: 100:50 100 - memory area with segment value 100 and offset from 50 to 100;
100:50 L100 - 100-byte area with segment value 100 and offset starting at 50.
5. Port address: two-digit hexadecimal value
6. Byte value: two-digit hexadecimal value
7. Byte value table: It consists of several byte values, or it can be a string enclosed in quotation marks
8. Drive letter: 0—drive A, 1—drive B, 2—drive C, 3—drive D, etc.