[rescue] Tatung Compstation NVRAM question

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On Sun, Jul 12, 2026 at 9:51 PM Steve Hatle via rescue
<rescue at sunhelp.org> wrote:
>
> All,
>
> I have come into a Tatung Super Computation 20SL - a clone of the Sparc 20.
>
> The machine comes up to the OK prompt without issue, but of course the IDPROM is invalid.
>
> I don’t have a problem with doing the Glitchworks board mod and updating the NVRAM. My question, though is do I need anything special for the machine ID?
>
> The current banner identifies the machine as the Super Compstation 20SL, and I’d like to not lose that. My research so far seems to indicate that using the generic ID 72 is OK.
>
> I’ve seen mention of the OBP command real-machine-type and I will try that out and see if it returns anything.
>
> The machine itself seems to have a stock SS20 logic board in it. It uses 2 50-pin SCSI drives, which surprised me. They sit in the case like a Sparc2 on different sleds.
>
> It has two SuperSparc processors I’ve not identified yet, ROM rev 2.22, and 144MB of RAM.
>
> I’m looking forward to firing this guy up! If you have any info on these, please feel free to pass it along.

Sun stopped using machine ID when they switched to openboot 2. The
machine type is hardcoded in the ROM with some auto detection for
later machines that shared ROMs. You can boot it with no NVRAM and it
will still know what it is. If you put that ROM in an SS20 it will
think it's a Compstation.