Sorry, I deleted the first version. As a reaction to the post from kozm0naut I did the circle point by point which caused a nicer circle, but 50% cpu time. I changed it back and now I have 4% cpu time. The clock is just ugly, but works ;)
I did some other optimizations as well to make it shorter but still readable.

You can actually update the version of a cart without deleting the original thread, just edit your post, upload a new version, and replace the link in the body of the post. You can add a note to let people know what's changed.

Hi, I apologize to have made you rework all that! While I used pset circles in my example, all I really meant was that you can add 0.5 to the very end of a trig op (or any math operation resulting in a decimal value) when you plan to draw to the screen using those values, in order to round them rather than floor them as draw operations do by default. The flooring behavior can result in graphics being drawn slightly "up and to the left" (closer to 0,0) of where they ought to be, which I think may be impacting just some of the tick marks (not the circle I think). Certainly no big deal, this is looking and working great! Good job!

Yes, I know what you meant :D I tried the rounding at the marks, but for me the effect was minimal. However, the PSET circle gave me a much nicer circle, but even this doesn't get the whole painting into a Mona Lisa ;)
Thanks again for the feedback, it's nice to know, that someone is looking at the simple code I wrote.

So...seems that I got it to update a cartridge.

I added a digital mode that you can toggle with the x key. My number sprites are not so well painted...