They have an emulator here: https://github.com/Datamuseum-DK/R1000.Emulator2

Notably it needs KiCad to run and takes ~140 hours to boot.

Seems like the reason for KiCad and the slow operation is that the emulation occurs at a really low level, and they've written a program to digitize all of the computer's schematics and convert them into netlists (which is then converted into systemC components for the emulator): https://github.com/Datamuseum-DK/R1000.HwDoc

a video explaining the process?: https://www.youtube.com/watch?v=oMRTr0bPuOA

Apologies for outdated information there...

On an Apple M2 CPU it runs around the same speed as the real hardware now.

(The first version based on the unaltered hardware schematics ran 4000 times slower than real hardware, it's been quite a journey :-)