It's the CMU micro kernel.  The hybrid "2.6" lived on in NeXTSTEP, and OPENSTEP, with various upgrades to bring it up to OS X. 

The RT as I understand it was a research machine, hence the BSD ports, and Mach port. 

What is interesting the more I dig around is that there was ROMP coprocoessor cards, and an OS/2 and DOS monitor program to let you boot BSD on the card.  Peripheral IO was done on the x86 side. 

If RT's are rare, I can't imagine how impossible it would be to get one of those cards! 

The BSD assembler and linker source is in the archives too, no doubt it'll help someone make a RT emulator. 

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On Tue, Feb 18, 2020 at 12:54 PM +0800, "Kevin Bowling" <> wrote:

Can you clarify what is Mach in this archive if I have a gap in my knowledge? I didn’t know the VRM had any direct relationship to Mach


On Mon, Feb 17, 2020 at 9:43 PM Jason Stevens <> wrote:
Interesting stuff!  And another version of Mach is buried in there. 

So the 4 csrg cd set may have updates to the romp support as it's an older version of the 5.1 kernel from 89...  Not that think there is any Mach romp users. 

From: TUHS <> on behalf of Charles H Sauer <>
Sent: Tuesday, February 18, 2020, 5:51 a.m.
Subject: [TUHS] Bitsavers' RT/PC, AIX, AOS, etc. recent additions

The Bitsavers' RSS feed ( seemed to me to be dominated by RT, AIX, AOS (BSD for RT), etc. stuff in the last week or so. I've only sampled a few items, but discovered a few things that I should have known (or knew and forgot?) while I was at IBM. -- voice: +1.512.784.7526 e-mail: fax: +1.512.346.5240 Web: Facebook/Google/Skype/Twitter: CharlesHSauer