[Simh] VAX firmware image

[Benjamin Huntsman]

Hi all!
   Please forgive me if this has been asked before, but I couldn't find a way to search the simh list archives.

   I'm interested in the VAX simulator, but was curious as to where the ka655x.bin rom file came from.  Did someone snarf it from a real VAX at some point, or was it compiled specifically for SIMH?   Supposing someone wanted to take the effort to add another supported model, where would they obtain the requisite rom?

   Also, I thought I read somewhere that the VLSI VAX microcode was released somewhere...  Would someone be so kind as to point me in the right direction?  I spent a few hours last night looking for it but came up empty.

Many thanks in advance to all!

-Ben