6502 assembly is really great for looping, especially if you are looping in one byte. The X register can hold your index, and the Branch Not Equal (BNE) opcode can check to see if you have hit zero or not (and branch to the location if you haven't). I decided to do this chapter on the Mac/65 because that's the editor / debugger that I am most used to with the Atari, and because eventually I want to get to the point with these exercises where I am able to branch off a bit and play a bit on my own with the bits that make the Atari unique. This chapter was pretty short though but had (IMHO) one of the best explanations of how the status flags and a binary digit map together. Seriously, I wish this book was on my radar 30+ years ago.