Re: Old Sun machines.

On Sat, Aug 30, 2025 at 12:45 AM mike.spooner.ux
<[email protected]> wrote:
>
> Hi all,
>
> Bear in mind that OBP 2.7 (as shown on the screenshot) is an *extremely* early PROM version for the SS10, and will seriously limit the particular MBus CPU modules that can be used in the system (under Solaris in particular, but also for boot and hardware reasons, probably under NetBSD too) -
>
> https://mbus.sunhelp.org/systems/sun/ss10.htm#t
>
> More recent PROMs suitable for both the SS10 and SS20 are available in several places on the 'net. 2.9.16 would be my absolute minimum recommendation for cached SuperSPARC modules, 2.19.3 for HyperSPARC investigations.
>
> Preferred option would be 2.25R (the Ross' minor variant of 2.25), which would allow any workable modules to be used.

The 2.7 ROM actually makes the machine more interesting to me as it
means it is a very early production model. It might even be a model 20
with an SM20. As a side note I've found there's some significant
performance differences between 2.9 and 2.19 and later ROMs. Some
times as high as 25%. I suspect, but have never looked into so have no
proof, that Sun might be doing some microcode patching on later ROMs
to work around bugs in SuperSPARC CPUs.