HP 3000 Series 37 on ebay in Germany (7954A, 9144AR, 30457A, 700/92
(German keyboard))
https://www.ebay.com.au/itm/HP-3000-Series-37-Computer-System-RETRO-SELTEN-…
Thanks to David Collins at the HP Computer Museum, I now have 11
different versions of the HP 3000 Series 64 [,68,70] microcode
SYSWCS64.PUB.SYS
and 3 different versions respectively of each of SYSWCS37 and WCSLE1 and
WCSLE2.
I've put notes up at
https://en.wikipedia.org/wiki/User:RDBrown/HP3000-WCS-Microcode
It's possible that one of the SYSWCS64 files may match the assembly
listing on bitsavers, but that listing could allow guessing the
architecture, assuming horizontal microcode and matching against the HP
3000 stack machine instruction set it implements.
Only the Series 37 rates a mention in the HP Journal, though the common
data between the SYSWCS37, WCSLE1 and WCSLE2 suggests they may share a
common microcode. Guessing the architecture would be more of a puzzle,
unless more documentation is found.
J. David Bryan's SIMH work gives a running MPE V for anyone to try.
I don't know what other minis of the era also have microcode available
as files - I read that the Vax 780 had 1k of microcode patch/extension
area for fixes or customer use.