I am looking for an inexpensive single board computer that I could program in assembly language, using limited facilities to load the object code from a PC and simple I/O peripherals.
Ideally I would like to be able to write in a reasonable time all the code on the machine myself. I don't want an OS in the way, as I want to have a program that writes in RAM some code and then branches to execute it. Arduino would probably be my best choice, as far as system simplicity suitable for assembly programming goes, but it has a Harvard architecture and it won't allow me to execute from RAM.
Years ago I was using a Von Neumann architecture 8-bit CPU that could branch execution to any address, no matter whether it was mapped to ROM, RAM or whatever. This is what I would like to do now.
I probably could write and load in Flash memory an interpreter of op codes written in RAM, but it is a very complex and time-consuming solution, unless virtual machines of this kind exist already.
Any suggestions on other workarounds with Arduino or of other micro-controllers I might use?