PIC Microcontroller based computer?

While I'm working on my calculator (which is progressing - square root special function added), I've started preparations for a new project. And as the title of this post states, it's going to be a PIC18F452 driven simple computer, which will work as an interpreter of a new programming language according to my style. It'll have it's own calculator, text editor, I/O to the computer through the rs232 and perhaps later - the USB, compiler and a simple instruction based UI. It'll be able to run one or two programs (written with the new language) at a time along with the text editor, compiler and calculator. It'll perhaps have an emulated I/O bus with other devices which will be available to play with using the custom language. I still can't predict boundaries of the 'future' computer's capabilities, but what I predict, is that it's going to be a superb home-made tool which I might use for, example a notebook(yes, it'll store text), an emulation device or simply use the calculator. So far I connected the LCD, established connection with the computer via the rs232 protocol and now to end the preparations, I'll need to add some ram to it. I'm really excited about this project, however first things first,... I have to finish my calculator.
NOTE: This project was inspired by another project posted on hackaday.com, which involves a PICAXE driven homemade computer. I don't remember the exact address of the project.