Yep, my thinking was that I would have a small monitor program, OS routines or a menu program (this will be my initial program) in the microcontroller. This won't need to be to large, just something I can use to load programs from an external storage medium (I'm still considering options) into the code memory (which is why it needs to be XRAM/code). I'm going to use a 4KB EEPROM for prototyping, then I intend to move my code to the internal 4KB of the chip I've selected. After that, I intend to replace the external EEPROM with addressable SRAM to recover the memory addresses for XRAM. I will use variable storage up to the first 6KB, then all my programs will start from the same point (1800h), to keep it simple (select a program, load it, run it). I can use this space for programs up to 59KB (64KB - 6KB vars & 1KB memory addressable devices) I will write an initial program to load programs into XRAM, then run that code. Of these programs that can be loaded into XRAM could be an assembly editor or a form of BASIC. (I realize If I wish to use an existing BASIC interpreter or assembler, it may have to be modified to start at 1800h). Also, I was aware I would need a logic AND to get the memory usable for code and XRAM (I forgot to mention that, when I was listing what would need to be on the board) Something else I will need is logic circuitry to change the way the last 1KB is addressed for my memory addressable devices. This is still an early drawing board stage. I'm also moving away from my intention of making this a BASIC machine in favor of making it an “assembly” machine (but still something I can write programs on). But my goal is still to have a "little PC" that I can write my own programs for, from the computer itself.