Hi! When I program in cc65 C, I usually use an optimization technique. It states that I can use parts of the OS's memory, a.k.a. Low memory, that aren't used during the course of a cc65 program can be used for a program's code and data. I like this technique, as it buys me a little extra space. AFAIK, the range from $0200-$02FF is used to read a line of keyboard input and can be used if a program doesn't use the ROM's routines for such, and the range $0300-$03FF is used by DOS 3.3 and is available when using ProDOS. Am I right? Where can I find a memory map for the Apple2 series?