[HECnet] SIMH and Alpha

I realise this isn't strictly related to hecnet but... I had a look around the SIMH repo at what looked like the beginnings of the Alpha simulator, particularly the CPU, including the PAL-code emulation for VMS. Relative to the VAX and PDP-11 simulators for example, it looks like there's a lot of work remaining however. Has it stalled due to lack of time, interest, knowledge.... or is there some 'engineering' issue with its implementation in SIMH that is presenting a hurdle too high currently to pass? Keith