Max size limit on MicroDIMM memory modules?

[Ethics Forge]

Can someone tell me (or link me to someplace that will explain it) why
144pin MicroDIMM (non-ddr) PC100/PC133 modules only seem to go up to
256MB? I for the life of me can't find what, if any, technical
limitation there is, and am curious if it is a technical or market
limitation that makes them only be available up to 256MB.

 

[George Macdonald]

Can someone tell me (or link me to someplace that will explain it) why
144pin MicroDIMM (non-ddr) PC100/PC133 modules only seem to go up to
256MB? I for the life of me can't find what, if any, technical
limitation there is, and am curious if it is a technical or market
limitation that makes them only be available up to 256MB.

Umm, they do go up to 512MB - check out www.crucial.com for SO-DIMMs,
assuming that's what you meant. Some mfrs may have just decided not to go
to the bother of the special chip packaging for 265M-bit chips or doing
SO-DIMMs using the 512M-bit chips... hardly a volume market.

 

[Ethics Forge]

No, I said, and I meant, MicroDIMM - it is smaller then SO-DIMM, and
generally used in subnotebooks

 

[The little lost angel]

Can someone tell me (or link me to someplace that will explain it) why
144pin MicroDIMM (non-ddr) PC100/PC133 modules only seem to go up to
256MB? I for the life of me can't find what, if any, technical
limitation there is, and am curious if it is a technical or market
limitation that makes them only be available up to 256MB.

I think most manufacturers just don't see much of a market for laptops
that old. So microDIMMs just don't get any bigger than whatever is the
largest at the point the technology got overtaken by DDR and now DDR2.
They just don't bother to make memory chips of higher density for the
older standard.

 

[daytripper]

I think most manufacturers just don't see much of a market for laptops
that old. So microDIMMs just don't get any bigger than whatever is the
largest at the point the technology got overtaken by DDR and now DDR2.
They just don't bother to make memory chips of higher density for the
older standard.

Might be much simpler than that. Perhaps the architecture of the chipsets used
with pc100/pc133 drams simply didn't/don't support more capacity-per-dimm...

/daytripper

 

[George Macdonald]

No, I said, and I meant, MicroDIMM - it is smaller then SO-DIMM, and
generally used in subnotebooks

Sorry but I've never messed with sub-notebooks. See my 2nd sentence then:
the packaging and chips to allow this form factor at that size was at the
end of the SDRAM era.

 

[George Macdonald]

I think most manufacturers just don't see much of a market for laptops
that old. So microDIMMs just don't get any bigger than whatever is the
largest at the point the technology got overtaken by DDR and now DDR2.
They just don't bother to make memory chips of higher density for the
older standard.

True about the changeover to DDR but PC-133 SDRAM 512Mb chips are available
now - apart from just the economics, I think it's more to do with the
packaging: FBGA was just being adopted for commodity DRAMs at about the
same time as DDR took over. I also recall the 512MB PC-133 SO-DIMMs I
purchased had the chips in a very strange package... looked like a blob of
asphalt glued to the DIMM substrate, 4 per side and probably would not have
fit on a MicroDimm.

 

[The little lost angel]

True about the changeover to DDR but PC-133 SDRAM 512Mb chips are available
now - apart from just the economics, I think it's more to do with the
packaging: FBGA was just being adopted for commodity DRAMs at about the
same time as DDR took over. I also recall the 512MB PC-133 SO-DIMMs I
purchased had the chips in a very strange package... looked like a blob of
asphalt glued to the DIMM substrate, 4 per side and probably would not have
fit on a MicroDimm.

But that's largely economics no? I'm sure they would had found a way
to fit it if they really wanted to. After all, there are DDR 512MB
microDIMMs, just not for PC100/PC133.

However, of course daytripper's comment about the chipset limitations
is probably the main thing pP