[rescue] Tatung Compstation NVRAM question

[Steve Hatle]

I put in a chip with the Glitchworks battery fix board and updated using 
the mkp method.

After the reset command, the machine comes back OK.

But - if I power down and unplug things for a couple minutes, when the 
machine comes back up it has the error

Incorrect configuration checksum

then sets defaults, turns on diag-switch?

When the banner prints, the values for hostid and the MAC address are 
there from what I programmed, but then there is the

IDPROM contents are invalid

message.

I’ve tried this with both machine ID 72 and 80 and with a set of values 
that have a known preset checksum for byte f instead of running the 
calculation.

Quick google did not turn up any likely answers.

I don’t have an OS installed to proceed any further than this. I’m kinda 
stumped on what to try next. I did not use THE chip from the Tatung but 
one I had already dremeled and prepped with the battery board.

Suggestions appreciated.

Steve


------ Original Message ------
>From "foo bar via rescue" <rescue at sunhelp.org>
To "The Rescue List" <rescue at sunhelp.org>
Cc "foo bar" <tokenalt at gmail.com>
Date 7/12/2026 10:03:01 PM
Subject Re: [rescue] Tatung Compstation NVRAM question

>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.
>
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