Removed RS232

While I've left in most of the I/O in case some mad scientist decides to turn the joystick ports into a Datasette or IEC interface, I don't think the RS-232 routines are worth keeping around. The Commodore 64's built-in RS-232 code could barely keep up with 1200 baud.

this copy of atari64.xex was compiled with the HELPRESET flag, so you can use the HELP key as a RESET key, until I figure out how to trap that key properly in a RAM OS. The roms are compiled without this option. This process isn't automatic in the build script.

BASIC, screen editor, and keyboard

The screen editor, keyboard, and BASIC interpreter are more or less fully functional.

There is no other I/O yet, neither disk nor tape nor printer, so you cannot save or load programs. If you want to save your programs, you'll have to use save states on an emulator.