This will loop sprite 1 through 4

T = 1
T += 1
SPR (1 + T % 60 / 30 * 2)

I was trying to figure out some simple math that basically does what the above code does.
I found that code in a demo cart and was happy to see that I was on the right track (sort of) but I don't understand what is going on here.

If I can't figure this out maybe I'm just not smart enough for this whole programming thing :(

It would be nice if you could move around the map editor with the arrow keys/d-pad.
Especially on the PocketChip.

If I really have to post my sloppy noob code I will but I am hoping that I can get a quick answer.
When my player sprite moves onto a grid flagged 1 then that grid is solid and the sprite stops moving. If the flag is 2 then it moves to a different room AKA different MAP() value(s)
This works as it should but the solid collision still applies to the tiles from the previous room. I do not understand this because the solid function should update when the new map tiles are drawn.

In other words. It looks like my character is in a different place but all the solid grid tiles are from the previous "room".