The following program illustrates how J automatically modifies RAM (Data Memory) addressing. The program has 4 channels. When a channel is activated by an off to on transition on its input, the corresponding output flashes 5 (NumberOfFlashes) times. (I made the flashes short so it would be convenient for you to test in the simulator). The flashes are counted in an array of RAM variables called Counter. Counter is declared in a defBYTE directive. The argument 4 makes the defBYTE set aside 4 contiguous bytes of RAM for 4 counters. When Counter is referenced in the program (in the DecMGoIfNZ instruction) J is used to select one of the 4 bytes.

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NumberOfFlashes EQU     5

        LaunchTask      TaskA,0
        LaunchTask      TaskA,1
        LaunchTask      TaskA,2
        LaunchTask      TaskA,3
        RunTasksForever

Counter: defBYTE        4        ;Array of 4 single-byte counters
TaskA:
        WaitOnK         0
        SetMem          Counter,NumberOfFlashes
TaskA1:
        On              0
        Pause           1
        Off             0
        Pause           1
        DecMGoIfNZ      Counter,TaskA1
        GoTo            TaskA

In the above example the address offset is just J. If there was a floating point instruction, the offset would be 4xJ, because each floating point variable uses 4 bytes of RAM. Similarly, for SuperTimers the offset would be 3xJ, because a SuperTimer uses 3 bytes.