How to tell is chip is Mcache

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b_egower

I have an ASUS P55T2P4 motherboard. It currently has 64 Mb Ram. I'd
like to increase it to at least 128 Mb. The manual says that in order
to do so so that the additional memory will be cached the onboard L2
chips need to be pipeline burst SRAM, not Mcache.

The chips are Winbond W25P012AF-7. Both the upgradeable TAG SRAM and
the L2 Upgrade Cache Expansion slots are empty.

How do I know if the existing on board cache is Mcache or burst SRAM?

If Mcache, the manual says that jumper J4 must be set to 64 Mb (and not
to 512) or it will be unstable.

If the onboard cache is Mcache am I really stuck at only being able to
cache 64 Mb of RAM?

I really want to increase the RAM to 128 Mb so I can run WindowsSE.
BTW, if I add a PCI/USB card to this motherboard will I be able to
access USB devices? The CPU is 200 MHz (WinChip CPU, but I'm not sure).
I've read that some USB cards need at least 233 MHz CPU's. I really
want to be able to access USB devices. This is the whole reason for
increasing the memory so I can use WinSE at a fairly decent pace. Or
would I be satisfied with it only running at 64 Mb. Any other gotcha's
I need to be aware of in this endeavor?

Thanks,
Bruce
 
I have an ASUS P55T2P4 motherboard. It currently has 64 Mb Ram. I'd
like to increase it to at least 128 Mb. The manual says that in order
to do so so that the additional memory will be cached the onboard L2
chips need to be pipeline burst SRAM, not Mcache.

The chips are Winbond W25P012AF-7. Both the upgradeable TAG SRAM and
the L2 Upgrade Cache Expansion slots are empty.

How do I know if the existing on board cache is Mcache or burst SRAM?
Click to expand...

IIRC, MCache was some bird-brained idea Intel had for the i430HX that mbrd
makers could use fast DRAM chips instead of PBSRAMs. I'm not sure that
Asus ever made a P55T2P4 with such a config... or anybody else for that
matter. How much cache memory do have soldered to the mbrd? Check out the
part nos to be sure but I'd be very surprised if it's not PBSRAM. The ones
I bought all came with 512KB, i.e. two 256KB SRAMs soldered in, but if you
have a COAST slot, I assume you have 256KB or 0KB??

Assuming you have some SRAM soldered to the mbrd, to cache >64MB you need
only to add a 16Kx8 <15ns SRAM for the TAGs. If there are no SRAMs
soldered to the mbrd -- apparently Asus made such things though I never
heard of, nor saw, them -- I think you're going to have trouble finding a
COAST module to fit.
If Mcache, the manual says that jumper J4 must be set to 64 Mb (and not
to 512) or it will be unstable.

If the onboard cache is Mcache am I really stuck at only being able to
cache 64 Mb of RAM?

I really want to increase the RAM to 128 Mb so I can run WindowsSE.
BTW, if I add a PCI/USB card to this motherboard will I be able to
access USB devices? The CPU is 200 MHz (WinChip CPU, but I'm not sure).
I've read that some USB cards need at least 233 MHz CPU's. I really
want to be able to access USB devices. This is the whole reason for
increasing the memory so I can use WinSE at a fairly decent pace. Or
would I be satisfied with it only running at 64 Mb. Any other gotcha's
I need to be aware of in this endeavor?
Click to expand...

No idea on this but a recent PCI card may not work anyway due to PCI
standards differences. Err, the P55T2P4 is just too old.
 
George,

Thanks for the quick reply.

George said:
On 1 Mar 2005 01:58:01 -0800, (e-mail address removed) wrote:


IIRC, MCache was some bird-brained idea Intel had for the i430HX that mbrd
makers could use fast DRAM chips instead of PBSRAMs. I'm not sure that
Asus ever made a P55T2P4 with such a config... or anybody else for that
matter. How much cache memory do have soldered to the mbrd? Check out the
part nos to be sure but I'd be very surprised if it's not PBSRAM. The ones
I bought all came with 512KB, i.e. two 256KB SRAMs soldered in, but if you
have a COAST slot, I assume you have 256KB or 0KB??
Click to expand...

The COAST socket is empty so I am assuming I have 256KB since there are
L2 onboard chips. But the manual has a very strong warning about not
setting JP4 to 512 if there is Mcache onboard, so I would think that
ASUS made at least some boards with Mcache. My board is Rev. 3.0.

But how do I check out the part nos.? I've looked on the Internet for
Winbond W25P012AF-7 and all I get are parts lists from various
companies. No further info about what type of RAM it is, just a price
or whether or not it is in stock.

Bruce
 
George,

Thanks for the quick reply.



The COAST socket is empty so I am assuming I have 256KB since there are
L2 onboard chips. But the manual has a very strong warning about not
setting JP4 to 512 if there is Mcache onboard, so I would think that
ASUS made at least some boards with Mcache. My board is Rev. 3.0.
Click to expand...

What was the original source of the mbrd? The only fools who would have
had Asus build MCache boards would have been large OEMs trying to save a
few cents. ISTR that the MCache never really worked right, with serious
restrictions to do with timing issues... mentioned in the Data Sheets.
But how do I check out the part nos.? I've looked on the Internet for
Winbond W25P012AF-7 and all I get are parts lists from various
companies. No further info about what type of RAM it is, just a price
or whether or not it is in stock.
Click to expand...

The closest data sheet I can find is for a W25P022AF-7 which you can get
starting here: http://www.dialelec.com/805.html. It's a 64Kx32 PBSRAM so
I'd think it's safe to say your part is also PBSRAM and very likely 32Kx32
- if you have two of them that'd make a total of 256KB of L2 cache, which
also makes sense given the COAST socket to add a further 256KB.

Though a 256KB COAST module would be nice, I think you'll have trouble
finding one. You don't need 512KB of L2 cache to be able to cache >64MB of
memory - the 256KB of L2 cache will also allow caching up to 512MB IFF you
add a 16Kx8 or 32Kx8 TAG SRAM in the DIP socket. If you do find a COAST,
make sure whether it has the extra TAG SRAM incorporated on the module,
since you dont need the 16Kx8 in the DIP socket then.
 
Thanks for the URL George.

I think I'll go ahead and get a upgrade TAG SRAM. It can't cost that
much. Nothing lost if it doesn't work. If it does, then my old P55T2P4
will still be going strong after 8 years, especially if I can get it to
work with USB (which the manual mentions can be enabled in the BIOS).

Thanks for your help.

Bruce
 
Thanks for the URL George.

I think I'll go ahead and get a upgrade TAG SRAM. It can't cost that
much. Nothing lost if it doesn't work. If it does, then my old P55T2P4
will still be going strong after 8 years, especially if I can get it to
work with USB (which the manual mentions can be enabled in the BIOS).
Click to expand...

Don't count on USB working. If you need it spend the $10-15 on a PCI USB2
add-in card.
 
Don't count on USB working. If you need it spend the $10-15 on a PCI USB2
add-in card.
Click to expand...

I imagine any USB2 card is going to require at least a PCI 2.1 host, and I
don't believe the 430HX met that minimum...
 
I'll probably get an older, used USB card somewhere. Even if it is only
1.1 I will at least be able to use some of my USB devices that are
backwards compatible. If nothing else my pen drive will work with it
and then I can at least change files with my Dell laptop which doesn't
have a floppy. Anything else beyond that would be icing on the cake.

Thanks for all the valuable insight from this group.

Bruce
 
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