Crossing compiling HP3000 MPE on a VAX was Re: got netbsd 2.0.3 to boot on 11/730 in sim

Lee Courtney charlesleecourtney at
Wed Jan 7 18:25:01 CST 2009

Hi Brad!

Topic drift, but your post reminded me of one of the most interesting uses for a VAX I know of. 

Back when HP was developing PA-RISC (mid-1980's) to replace the 16-bit stack architecture 3000 we used a VAX-750 running BSD to host a PA-RISC simulator. I was working on the MPE boot-strap code at the time and used the simulator to write in PA-RISC assembler (no HLL compiler yet) and run tests. We had one 750 for the entire MPE OS Lab, although only a few of us were using it. Not surprising that the turn-around for compiles and debugging reminded me of mainframe batch turn-arounds from school, at the end of the semester of course. Barely usable.

We soon got proto-type CPUs implemented in TTL that plugged into the back-plane of a very heavily hacked Series 44 (desk form-factor 3000). That way we could have hardware'ish speed and use real peripherals. Huge improvement before we got real prototype hardware to do OS bring-up on.

Of course this was all very hush-hush at the time since HP was locked in a death struggle with DEC in the mini-computer market. Would have been bad press for it to get out that HP used DEC computers to design its new 32-bit computer architecture. 


Lee Courtney

--- On Wed, 1/7/09, Brad Parker <brad at> wrote:

> From: Brad Parker <brad at>
> Subject: got netbsd 2.0.3 to boot on 11/730 in sim
> To: "General Discussion: On-Topic and Off-Topic Posts" <cctalk at>
> Date: Wednesday, January 7, 2009, 9:38 AM
> The vax unix nerds on the list might find this mildly
> interesting:
> I hacked a copy of simh vax780 to look like a vax 11/730. 
> I made a
> modified version of the standalone netbsd "boot"
> program which does nfs
> loads from a deuna (it will do copy's too, which is
> handy at times)
> With that I finished debugging netbsd 2.0.3 on the 730. 
> I've gotten it
> to boot to a shell prompt on a simh 11/730 with 4mb of
> memory using an
> nfs root. woo hoo!
> So, next I'll make a disk image and put my unibus scsi
> card in my real
> 730 and debug that.  With any luck it will just work.
> Once it's going on real hardware I'll get it going
> on the latest netbsd
> (4.0?) and get a patch back to the netbsd/vax maintainer.
> [for those who care, I use a linux program which simulates
> the tu58 to
>  boot my 730.  I made a boot tape image with putr which
> contains the
>  netbsd boot program (as well as the other files needed to
> load
>  microcode, etc).  I plan to spend some time and make a
> linux program
>  which will put together valid tu58 tape images, just to
> make my life
>  easier, since putr requires DOS.]
> I have to give the netbsd folks a lot of credit.  Their
> posix build
> system is very handy.  But note that releases before 2.0.3
> will *NOT*
> build on a posix machine - they require native netbsd to
> build cleanly.
> I've always had a soft spot for the 730; maybe because
> the 780 was
> just too damn big! :-)
> -brad

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