An Intel MMC-1 question

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I have an old Chembook 7000M laptop with a big 15" 1024x768 screen, so
it is worth a little effort to keep it running fast enough to be useful.
It came with an Intel Mobile Module CPU MMC-1 running at 233MHz, which I
later upgraded to 300MHz. Then, some dirt recently blocked an air
passage and it overheated and shorted out, so I am back to using my old
233MHz CPU.

I checked eBay for a new processor, and discovered that there are MMC-1
processors up to 400MHz, which would help a LOT since I use Dragon
NaturallySpeaking speech recognition software that wants all of the
speed that it can get. However, Chembook says that my computer is only
rated for 300MHz. I can't tell whether 300MHz was just the maximum speed
available when my computer was sold, or whether there is really a 300MHz
technical speed limit of some sort.

Can anyone here shed some light on this? Is the MMC-1 external timing
the same at 400MHz as with 300MHz? Does 400MHz draw a lot more power
than 300MHz? Will 400MHz probably work?

eBay prices for 300MHz run around $30, and for 400MHz around $50. I'd
hate to waste $50 on something that won't work, or worse yet burns
something ELSE out.

Thanks in advance for any light that you can shed on this.

Steve Richfie1d

Re: An Intel MMC-1 question

Steve Richfie1d wrote:
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Can't help you on the specific case, but there have been speed limits in
the past. Consider the age where 333mhz pII's were more expensive than
400mhz. (that was the age of the 440lx and the 66mhz fsb.)  You might be
able to read through your manual and look for things like bus speeds
(compare them with that of the 400mhz.), etc.

poly-p man

Re: An Intel MMC-1 question

Poly-poly Man:

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Yea. Since I posted, I managed to find someone's private copy of Intel's
44-page spec sheet on line. Intel very carefully avoided showing ANY
external differences that were a function of speed. Not only is the bus
speed the same (selectable to 60 or 66 MHz), but the power, cooling,
timing, and functionality are all said to be absolutely identical.
Hence, unless someone else here knows better, I am going to spring for
the $50 and try it. With luck, this will buy another year of life for my
  backup laptop.

The 400MHz units on eBay are USED. I wonder if there are any significant
aging effects, especially in light of the fact that I fried my previous one?

Also, the spec sheet tells of a register with a bit that can be set to
put the CPU to sleep when it overheats. Obviously the BIOS isn't setting
this rather important bit. I would think that this would be an important
bit for people who are overclocking their systems, to keep from frying
their CPUs. Perhaps someone has written a utility to access this bit. Do
you know anything about this?

Steve Richfie1d

Re: An Intel MMC-1 question

Steve Richfie1d wrote:
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There are two versions of the P-II MMC-1 modules. The first, in speeds from
233 to 300, has separate, half speed, 512KB cache (like the desktop P-IIs)
while the second, in speeds from 266 to 400, used the newer on-die 256KB
cache (like the later desktop P-III coppermines). Physically and
electrically there should be no problem and the on-die, faster speed, MMC-1
actually produce less heat: 11.5W vs 13.9W for the older version.

The potential problem is whether the BIOS will initialize it or not and,
unfortunately, I can't answer that question as it depends entirely on what
the manufacturer decided to put in the BIOS code.

If the 300 you had in there was also a 512KB version then you have no clues
to go on but if it was the newer on-die MMC-1 you have a better shot at it
since it apparently initialized it's cache so only the speed matter would

As a side note, the on-die cache version is not only clock speed faster but
it's faster clock per clock because the on-die 256KB cache is faster, by
about 25%, than the 512KB cache even with the smaller size.

You can tell by the part number which, for a 300MHz 256K cache module,
looks like PMF3001001AA

the PMF specifies processor module, MMC1.
the 300 is the speed
and next two digits are the cache type with 02 for 256KB
(the remaining digits are design and processor rev levels)

The older 300Mhz 512KB cache module number looks like PMD30005001AA

The PMD is different than the PMF, even though it means the same thing, and
the cache number is 05.

Re: An Intel MMC-1 question


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My Chembook 7000M is really a relabeled Kapok 8700M. Maybe there is some
knowledge of which CPUs work in it out there somewhere.

I presume that this is a not-too-infrequent problem or you wouldn't have
mentioned it.

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My fried 300MHz part number is PMD30005002AA, and the 233MHZ part that I
am now running on is identical except for 233 instead of 300 in the part
number. The BIOS reports 512K Cache when I boot it up.

If Chembook's claim that 300MHz is the maximum is indeed correct, then
from what you are saying, only PMD boards will work in it.

Hmmm. I'll beat on Google, but it sounds like the $50 PMF part may be
much more of a risk than I had realized.

**T*H*A*N*K*S** for probably saving me $50 and a lot of aggravation.

Steve Richfie1d

Re: An Intel MMC-1 question

Steve Richfie1d wrote:

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Well, I don't know how frequent it is but I have an rather unusual unit
made for industrial use that won't take anything but what is in the
original processor list. I don't say it's representative but, at any rate,
it's 'one'.

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That's what I was afraid of because it doesn't help in telling whether the
256k cache version would work or not.

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It may very well be that was the fastest one when they wrote it and they
might not have bothered to test the newer ones, especially if they had a
newer notebook for sale by that time anyway.

Well, I dropped by their site and the 7000P uses the 256K cache modules but
it's not exactly the same as the 7000m in other ways, like more display
memory, more RAM capacity, firewire, etc.

I was hoping maybe it would look like the same thing but since it doesn't
you can't draw any conclusions.

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I was lucky in that I bought the module from a place that let me return it.

If you could find a BIOS guru somewhere they might be able to patch in the
code for one, or tell you if that one will accept it.

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