Comment by pragma_x

FWIW, you can make software that runs on Harvard architecture chips. They feature distinct address spaces for ROM and RAM. It's been a while, but it's how Atmel/Microchip AVR micros work.

https://en.wikipedia.org/wiki/Harvard_architecture

That said, I'm unaware of any programming language (outside assembler) that takes that split to heart in a higher-level way.