HW 12
(due at the final exam)
1) Write a C program that requests, reads, and echos the values of the variables X
and Y (one digit each) from the keyboard, and then prints the sum of the two
numbers. Use the scanf and printf standard I/O functions. Test the program,
and show pertinent “snapshots” of the stack.
2) Now write your own scanf subroutine (function) to replace the standard I/O
scanf function used in your program (I would keep it simple). It must be
assembled to be placed at the correct location in the simulator (Unfortunately
we don’t have a linker to do this automatically for us. That would be the normal
procedure.). Again test your program, and show your code replacing the scanf
function and pertinent “snapshots” of the stack.
3) Now, the fun part! Modify your program so that the scanf function operates
with an interrupt. You will now need to add an interrupt routine (which you can
assemble with your scanf function if you like), and will also need to load the
interrupt vector and arm the device (You can do this by hand in the simulator if
you like.). Again test your program, and show your code in the simulator and
pertinent “snapshots” of the stack. Good Luck!
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