@AWJ I wont be willing to use a disassembler until I go through it like this at least once. It's a good learning experience. Like a trial by fire.
I would like to use a debugger to double check things and I considered it for this one instruction, but it's a bit of a circular issues:
Without knowing the code I can't know where it occurs (unless that had been how I discovered it).
And without knowing what it is, I can't know what to trigger to reach that place in the code and get into the loop that would trigger my breakpoint.
Also, I continue to make headway, and, again, I've corrected my branches in regards to the sign issue which (@AWJ) I probably wouldn't have thought about unless I had done this in such an archaic manner, but this itself gave me trouble.
Just by how the code lays out, I know I have a STA, LDA, ASL, TAX, JMP, then since I know the CPU just follows commands and doesn't know better, I know once it returns from the JMP (via an RTS) I will hit E3 80, i.e. SBC 80, then 88, i.e. DEY, 81 1C, i.e. STA_1C_X, and then the issue, I hit 82 4E 82, i.e. BRL 824E.
Thanks to AWJ I know about the sign now, so I take this, 2's complement, and then take the location of the first byte of the next operation in this case it'd be an F position) and subtract.
This results with a direct branch to a COP instruction, which I now know doesn't work.
Consequently I am left with only one thought, and that is that, in that JMP, it doesn't return. But that would seem weird. Why enter a routine if you never return from it? (Since I didn't hit a breakpoint at the start of the code, [i.e. assuming the hex labels of my editor match those I'd input into a breakpoint viewer], I know it isn't some main loop which is hit once and then never goes back).
I also would like to say thanks to all who've commented, especially AWJ for consistent responses.
Upon reflection of this post, I think I'll follow that JMP and see where it leads. If there is an RTS, then my issue remains, if there doesn't, then I ignore it until everything else is worked out.
Also, it may appear I am encountering what Dr. Floppy referred to (although not really since they aren't branches) but rather jumps that just jump to a location which stores 60h, i.e. RTS. (Although I don't see the point in that. Why JMP to a RTS if there aren't even instructions to change the stack pointer. I remember a thread on here about compilers being bad back in the day, but I doubt this is compiler based).
[As I edited AWJ commented so I may be able to remove this part about the RTS. Since JMP doesn't push anything, the RTS will undo the Jump Subroutine before it. I.e. if A calls B, and B jumps to RTS, then RTS doesn't return to B, but rather to A).
Last edit of this post before I make a new one:
But what if it's a JSR calling an RTS? JSR is jump sub routine, hence RTS should return back to its spot.