You see, the truth is that when you start doing programs that are similar to real-world programming problems (for entire systems, not just one little motor), you have to consider the entire problem. Stop and Open Door- you have to stop the thing, but if you did not close the door in SBR 6, then you could sluff off that part, but you will have to do it later in Exercise 3, so why not set up things correctly on the first go-around?) Track Car Movement - just the rungs that that check for presence of car on 4th floor) Close Door and Move - you could do without it and leave the door open, but then you will have to later rewrite your entire routine when you do Exercise 3!) Next Request, or Wait - You might as well do all of this one - no harder than just doing part for the 4th floor!)
Only part of this one, the rungs that check for floor requests on the 4th Floor) Initialization - of course you have to do the preliminary variable set-up), SBR3 (Called U3 in the Main, for some obscure reason. The answer is going to shock you: To do Exercise 2, you need the Main Ladder 2, AND these Subroutines: Which one of the subroutine do I use to do this exercise?
Is that all they wanted? All of the U3, U4, U5, and so on is very confusing to me. From my understanding, they want the car to move to the 4th floor and stay there.
