I got really annoyed with myself trying to visualize coordinates on the screen. So I used my l33t excel skills to throw a grid together with some reference numbers.

I am doing this bastard oldschool.

Brilliant!

It is how we did most stuff back in the dark ages ;)

I would use bits of graph paper and map out the pixels in relation to how things should look. I then converted into hex and machine code.

I've got HUNDREDS of pages of graph-paper with little sketches all over them - some as far back as when 'teen' wasn't in my age. :D

Can share some if you like.

Ha, very nice! I bought myself a pad of fine-ish grid paper a while back for PICO-8 sketching purposes, just like 1/8" squares with major grid marks at the inch, and that's been useful when I want to think about sub-screen layout stuff when not in a place to compute.

But I dig this screen-wide version. If it were me I'd segment it by 8s instead 10s because that maps better to the sprite memory and the even subdivision of the screen by powers of 2, but that's personal preferences as much as anything.