Happy debugging.
-A 100 0AF7:0100 MOV AH, 4C 0AF7:0102 INT 21 0AF7:0104 [Press Enter] Now run it with G (Go). The program will exit back to DEBUG. To see what’s at address 0100 : Download Debug Exe For Dosbox Windows
U 100 104 Output:
Type Q and press Enter to quit back to DOS. Part 6: Basic DEBUG Commands (with Examples) Here are the essential commands to get you started. Each command is a single letter followed by optional parameters. 1. View CPU Registers – R Type R and press Enter. You’ll see: Happy debugging
To change a register value, e.g., set BX to 1234 : To see what’s at address 0100 : U
R BX DEBUG will show the current value and wait for a new hex value. Type 1234 and press Enter. Let’s write a one-instruction program that exits cleanly:
Whether you’re learning low-level programming, repairing old software, or just curious how DOS worked, DEBUG is a tool worth mastering. Now that you have it downloaded and configured, start with the examples above and explore the rest with ? (the help command inside DEBUG).