NDresevic / dos-debug-tool

DOS debug tool intended to facilitate solving problems in DOS programs using TSR. Main functionality is showing values of the main registers and the 6 most recent values on the top of the stack.

DOS Debug Tool

DOS debug tool intended to facilitate solving problems in DOS programs using TSR. It has the following functionalities with listed commands.

• domaci1.com -start starts debug TSR program, giving following features
• Listing values of registers ax, bx, cx, dx, si, di and listing values on the stack (top-most 6). The displayed values are constantly on the screen, where key F5 shifts between the display of the values of the general purpose registers and the stack display. The displayed values are also refreshed only when pressing the F5 key.
• domaci1.com -peek aabb ccdd displays value (byte) located on given address in memory, [aabb:ccdd], in base 16 where aabb represents the segment and ccdd the offset
• domaci1.com -poke byte aabb ccdd ee change value (byte) located on given address in memory, [aabb:ccdd], in base 16 where aabb represents the segment and ccdd the offset, and ee is the new value written to the given address
• Shift the position of the displayed values on the screen by one character using keys: F1 shift left, F2 shift right, F3 shift up and F4 shift down
• Showing current time in format HH:MM:SS
• domaci1.com -stop stops TSR

DOS as an operating system is not reentrant, so to solve this problem, special flags are set to indicate if there is an active system call. Testing these flags gives information whether or not it is safe to make the second system call. For better understanding take a look at http://www.plantation-productions.com/Webster/www.artofasm.com/DOS/ch18/CH18-3.html#HEADING3-4