I just replaced the idprom (AKA NVRAM + battery; I used an ST M48T08-100PC1) in my Sun SPARCstation 20. The original one was inside a rectangular holder with a tab on each short end; it had passthrough holes on the inside so the pins of the chip could connect to the motherboard.

I was having trouble getting my system to boot (as far as I can tell, I just needed to wait for it to go through the lengthy POST, since the only output you get during that is keyboard LEDs and terminal output), so I tried inserting the new chip directly into the motherboard (without the enclosure), and I found that it worked.

What is this thing called? And what is it used for?

Pictured is the enclosure on the left and the chip on the right.Mystery enclosure on left; chip on right

  • 1
    To ease the extraction of the chip.
    – TEMLIB
    Jun 9, 2016 at 23:00
  • TEMLIB: I didn't realize when I first approached it that I could just lift it up by those tabs; I stupidly ended up rocking it side to side in the direction perpendicular to that axis. I was thinking the whole box was much more permanently attached to the motherboard. Jun 10, 2016 at 18:01
  • unrelated - but is that an Atari ST in the background?
    – user6879
    Sep 12, 2017 at 7:03
  • @HorusKol Yes, it is. A 1040STF. Sep 13, 2017 at 13:18

1 Answer 1


Not sure what it is called, but as far as I know it is just a tool that helps in the removal of the chip by allowing you to pull up on the tabs.

In my experience its just much easier to take a screwdriver to the chip socket, so I just removed it on my Sun Ultra 10. (Especially considering where it sits on the board.) Not easy to remove by hand with this installed. Also you could accidentally bend the pins removing it that way.

Of course, this didn't matter when they were new because you were replacing the chips, but nowadays you will likely be modding the chip to take a CR2032 so that you don't have to find NOS expensive replacements.

  • 1
    When you say "Not easy to remove by hand with this installed. Also you could accidentally bend the pins removing it that way." are you referring to removing it with the holder? Jun 9, 2016 at 23:43
  • Yes, the holder lets you apply more force to extracting the chip than the gentle rocking that would be done with the proper chip extracting wedge were used. This encourages you to lift one end out farther which would lead to bent pins on the other end. The pins have a rectangular cross section and this kind of action would lead to premature failure. Of course you should only ever be using the the thing once per chip. Jan 7, 2017 at 1:51
  • In principle, since the holder is keyed to only go on the board one way around, it is also helping you put the chip in the right way around. (But since there's nothing preventing someone from taking the chip out of the holder and putting it in back in the holder upside down, it's certainly not foolproof)
    – rakslice
    Jun 27, 2018 at 2:08

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