What is this slot called and what is it for on a Pentium 1 motherboard?

Here I give you the Asus P/I-P55T2P4 rev 2.1 board:

Pentium 1 Motherboard

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    @ϺОŞΣŞ That link says " hazard an answer based on the limited information provided" <-- It's not like he provided limited information. He provided the motherboard model and a picture of the slot. Not a 'vague description'. So the vague descriptions(which don't really apply here), were more an issue with the gaming/english/literature sites where they made popualr tags, see the blog post you linked to.
    – barlop
    Sep 9, 2014 at 21:14
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    That picture brings back some memories...
    – user256743
    Sep 9, 2014 at 23:12
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    Just for the records: the motherboard is a "P/I-P55T2P4" by ASUS.
    – Samir
    Sep 10, 2014 at 9:50
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    @barlop A similar question I posted (superuser.com/questions/669399/…) was closed for same reason, and this was cited: meta.superuser.com/questions/6073/…
    – user201262
    Sep 10, 2014 at 17:17
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    @ϺОŞΣŞ However the answer cites that "the question is geared to only help a single person." Mine isn't, I don't even own this motherboard. I was researching P5 architecture and kept seeing that slot. I couldn't find any info, and didn't even know what terms to use to search. Apparently others find this information helpful as they have up-voted the question.
    – Thraka
    Sep 10, 2014 at 20:37

2 Answers 2


That's CELP! Card edge low profile!

It's a type of slot (or socket) used for expanding the L2 cache on some early–to–mid 1990s computers. The card that would fit inside it was called COASt! Cache on a stick! The stick would be populated by SRAM memory chips.

The standard was originally defined by Motorola to be between 4.33 and 4.36 inches (110 and 111 mm) wide, and between 1.12 and 1.16 inches (28 and 29 mm) high.

Source: http://en.wikipedia.org/wiki/Cache_on_a_stick

The missing puzzle piece...

cache on a stick

  • 1
    The question asked for the name of the slot, not the card. In the same article you linked, it calls the slot "CELP". I gave you an upvote anyway. :)
    – Jason
    Sep 9, 2014 at 21:40
  • You quote from wikipedia " but with newer computers cache is built into either the CPU or the motherboard." <-- They had cache but his and perhaps that was an upgrade. His manual indicates it had cache -pipeline burst cache-on there even without any stick/card.
    – barlop
    Sep 9, 2014 at 21:52
  • @Jason You are right, of course! The previous poster had already answered the question about the slot, pretty much. I didn't want to rub it in even more. :) He took the name from the manual. I worked on the identification from another direction. Because what goes into that slot is more important than the slot itself! ;) That's why the main article on Wikipedia is titled as COASt. But I couldn't have done it without his help. I hope you like CELP better! ;)
    – Samir
    Sep 9, 2014 at 22:32
  • @barlop Good point! Installing some extra COASt was this "micro" upgrade (it's not like people were raving over performance improvements) of the 90s. It's not like there wasn't any cache on-board already. The computer wouldn't work without it. Meaning the slot would have been populated already, completely removing the need for an expansion slot in the first place.
    – Samir
    Sep 9, 2014 at 22:37
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    IIRC this could also be L3 cache if you used the board in combination with an AMD K6-III. Back then CPU sockets were not specific to one company.
    – MSalters
    Sep 11, 2014 at 12:03

It's the L2 Upgrade Cache Expension Slot. Check Manual for details

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    Props, who would have thought to read the manual! Sep 9, 2014 at 19:15
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    Fun fact: a slot on a desktop motherboard for cache memory (not RAM) was never really seen again after this. Then in 2013 (17 years later), M.2 slots were introduced, which are commonly used for SSD caching.
    – Jason
    Sep 9, 2014 at 20:53
  • I had looked at the manual to another board and I couldn't find it (it didn't even have a diagram) and just found this picture online. Didn't think to look for that manual instead.. Oh well, points all around :)
    – Thraka
    Sep 9, 2014 at 20:58
  • What do you call the card that goes in there? I'm trying to locate a picture of it. I found one for an old Apple computer on Wikimedia Commons.
    – Samir
    Sep 9, 2014 at 21:16
  • @Blackjack00. I've owned about 3 computers so far, none were shipped with an instruction manual for the motherboard.
    – Nolonar
    Sep 10, 2014 at 19:45

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