[chrissmithuk]

Actually most can't be emulated because emulators don't exist and those which can typically can't be emulated correctly (Sparc emulators for example which are notoriously sparse and bad quality).

Some of the architectures also have different endianess and incredibly complicated peripherals to the cost effective host machines as well meaning that it's actually more power efficient to run native. A headless 100MHz VAXstation for example draws less power than the equivalent host that would be required to provide a full, accurate emulation with peripherals. These aren't arcade machines.

[rbanffy]

OTOH, the preservation of such historically relevant architectures would benefit enormously from emulation. This is an aspect that should get some attention and which could, possibly, open up another funding avenue to the project as a side effect.

[chrissmithuk]

Not really. The OS syscall interface, ABI and the fact everything is abstracted via your C compiler normalises the differences between the machines pretty well meaning you only end up dealing with portability issues.

Portability issues is where real hardware benefits. It's where you have battles of unusual register sizes, endianess, host/network order differences, different memory models and memory protection, different performance characteristics, different timings and different exploits.

Unless the emulation is 100% accurate, including timing, which is a really difficult thing to do (look at the effort MAME goes to), then the benefits over real hardware is moot.

Emulators are also expensive to write due to the above, have their own bugs and don't always recreate the bugs in the real hardware (which are sometimes exploitable).