SIMH on low overhead platform

John Klos john at
Wed Aug 19 12:55:20 CDT 2020

On Aug 17, 2020, at 12:43 AM, Tom Hunter via cctalk 
<cctalk at> wrote:
> >
> > Has SIMH been ported to a low overhead (instant-on) platform?
> I use NetBSD on a surplus HP ProLiant DL360p Gen8, NetBSD 9.0-stable 
> boots in just a few seconds. The hardware itself takes a couple minutes 
> to go through its bootstrap process, however. (I should have considered 
> setting up ESXi and installing NetBSD atop that to avoid the hardware 
> boot process, since I'm regularly rebuilding and updating NetBSD?)

It's funny, but it seems to be true that the pricier hardware takes longer 
to POST. I bought several AMD AM1 CPUs / motherboards when a set only 
cost $50 and I use them as routers running NetBSD. From power on to 
booting the kernel is less than three seconds. Getting to fully multiuser 
is less than 30 seconds, even with DHCP.

> Oh yeah, NetBSD 9.0-stable 64-bit also only takes a few seconds to boot 
> on a Raspberry Pi 3B+. It's easy enough to just throw on an SD card and 
> try out. Alas the Raspberry Pi 4 isn't supported yet by NetBSD, though I 
> think it's coming along. An RPi4 with 4 or 8GB of RAM should be a very 
> nice turnkey SIMH server.

Yes, the Pis boot very quickly. The Pi 4 is supported, but just not in 
NetBSD 9. The Pi 4 takes a wee bit longer to boot because it uses UEFI, 
but I think the difference in performance is well worth the extra few 

A bonus is that you can boot directly off of USB attached storage 
(although I'm still loading UEFI and the kernel off of the SD card).

SIMH runs very well on the Pi 4.


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