AndyGeo wrote
I don't get this 100%...
@END
D;JEQ
I know the A register is set to the address of where to jump if a jump is made.
So further down the code it goes to the next line such as:
@END?
Correct, when the D value matches the jump condition, the next instruction executed will be the instruction at the address in A, which in this case is the @END after the (END) label.
Also in figure 4.2 the A register is set to @LOOP and 0;JMP.
I guess this is stating the end of a loop and instruct it to run to the test but I can't see how this is working.
@LOOP
0;JMP
always jumps to (LOOP) so the loop adds the next value.
(END)
@END
0;JMP
is an "infinite loop" -- a loop that never terminates -- that keeps the computer from running wild after the program completes.
The test script doesn't just run after your program ends. It actually starts before your program. It is responsible for loading your program and controlling the number of instructions the computer runs during the test, as well as checking your program's results.
--Mark
Locked
