Are there any current non-Harvard architecture microcontrollers?

Question

I have used and like the Atmel ATMEGA and ATTINY series microcontrollers, and think them quite good. One thing I am not terribly fond of though is the fact that they (and Microchip PIC uC family also) are all Harvard machines, meaning I can't really put external memory to use or execute out of RAM, only the flash.

While there are obvious advantages to this design, it makes it technically very difficult to do things like FORTH using an AVR or PIC. (I know there is at least one implementation, but it does not work like a normal FORTH and will wear out the flash rather rapidly)

FORTH was originally created for interactive machine control type systems where lots of flexibility was needed, so things like the Z80 or 6809 were used as microcontrollers with the control program executing out or RAM or some other storage device.

Does anyone know of current devices of similar complexity (preferably available in DIP packages) to the AVR/PIC that are von Neumman machines?

Answer 1

You may also have a look at the Zilog eZ80. Since they're binary-compatible with the old Z80, you should be able find a FORTH implementation that runs on them, but you'd probably need to run it on top of good old CP/M :)

Also, these are the only ones that I found that have the memory bus accessible from the outside, i.e. allow code execution from external memory.