Initialize register A to0 .
Load a value from Port E into register A.
Use the simulator switches to set values on Port E.
Mask the 8 bits in to make the high order 4 bit equl to 0 and the lowest order 4 bits equal to the value in the lowest four bits of register A.
Output the result to Port B.
Connect port B to the LCD for display.
If the BCD value is valid, read another value from Port E.
Check for the Masked value in register A to be a valid BCD code, stop when the value is illegal.
Questions to be demonstrated:
Does your program mask the high order bits when the input is great than $0F?
Does your program always stop when the input on Port E is an illegal BCD code?
Does it stop if the input is2 ?
Does it always stop if you change the input value while it is running?
Answer the questions by demonstrating your program to the TA running with inputs of1 , and then2 , and then changing the input on Port E while the program is running.