The first step I took for the assignment was to store the memory space of the top left word of the screen to a variable. I'll lay it out by the respective comments for each line here:
// load the start of the screen's memory map in the A-register
// Set D-Register equal to that address
// Declare a new memory space (e.g. "top_left") to save that value
// Set that memory to what is saved in the D-Register
When doing this whole screen but the very first word of it's memory map blacken when pressing a key. Only if the the last instruction from above is
// Set that memory space to what is saved in the D-Register -1
the whole screen blackens.
Just from the information given, can somebody explain to me why that is? If not I am happy to send my code.