I like doing 6502 assembly on my Apple II+ (clone), and just assembled a PX 16C kit, which is a clone of the HP 16C calculator. Really great for hex and binary,

I like doing 6502 assembly on my Apple II+ (clone), and just assembled a PX 16C kit, which is a clone of the HP 16C calculator. Really great for hex and binary, and all sorts of bit manipulations. One day I may buy an actual HP 16C, but I couldn't get myself to spend the money on one just yet. I have the PX sitting next to my Apple II and it's great. I also have an HP-41C, a 48S, and a Sharp PC-1500, because I'm a nerd.