PC-133 memory Mbit rating. How do you work it out?
 

I'm trying to add memory to my computer which takes PC-133 SDRAM by
buying some second-hand. According to my motherboard manual it will
only recognise a DIMM size of 256 MB if it's using 128-Mbit device
technology.
So my questions are, is there any easy way to tell if memory is
128-Mbit, and what's the difference between 128-Mbit & 64-Mbit
memory?

After doing a bit more research, I'm getting on the right track to
finding an answer. I suppose I just need someone to explain the
numbers to me.

For instance I found some memory advertised like this:
PC 133 (32x64) 256 MB
256 Megabyte 168-pin 3.3 Volt Non-Parity 133MHz SDRAM

And then some more expensive memory from the same company described as
such:
PC 133 (32x64) 256 MB 16 chip (16x8)
256 Megabyte 168-pin 3.3 Volt Non-Parity 16 Chip (16x8) 133MHz SDRAM.

Looking at my motherboard manual, it lists different memory
configurations, but I'd really like to know what the numbers mean.

Thanks,
Dash

==============
Posted through www.HowToFixComputers.com/bb - free access to hardware troubleshooting newsgroups.

Dash wrote:

I'm trying to add memory to my computer which takes PC-133 SDRAM by
buying some second-hand. According to my motherboard manual it will
only recognise a DIMM size of 256 MB if it's using 128-Mbit device
technology.
So my questions are, is there any easy way to tell if memory is
128-Mbit, and what's the difference between 128-Mbit & 64-Mbit
memory?

After doing a bit more research, I'm getting on the right track to
finding an answer. I suppose I just need someone to explain the
numbers to me.

For instance I found some memory advertised like this:
PC 133 (32x64) 256 MB
256 Megabyte 168-pin 3.3 Volt Non-Parity 133MHz SDRAM

And then some more expensive memory from the same company described as
such:
PC 133 (32x64) 256 MB 16 chip (16x8)
256 Megabyte 168-pin 3.3 Volt Non-Parity 16 Chip (16x8) 133MHz SDRAM.

Looking at my motherboard manual, it lists different memory
configurations, but I'd really like to know what the numbers mean.

Thanks,
Dash

..


32M x 64 bits, equals 2048Mbits/256MBytes. 32Mx64 indicates a non-parity 256MB DIMM. 32Mx72 would
indicate an ECC 256MB DIMM.

The second 256MB module, with sixteen 16Mx8 (16M x 8 bits equals 128Mbits) chips is the type needed
for your motherboard. The first 256MB module probably uses eight 256Mbit chips, and would not be
supported by your motherboard.

steven67@wrote:
32M x 64 bits, equals 2048Mbits/256MBytes. 32Mx64 indicates a
non-parity 256MB DIMM. 32Mx72 would
indicate an ECC 256MB DIMM.

The second 256MB module, with sixteen 16Mx8 (16M x 8 bits equals
128Mbits) chips is the type needed
for your motherboard. The first 256MB module probably uses eight
256Mbit chips, and would not be
supported by your motherboard.

Thanks for that! Maybe I'm being dumb, but I'm only half way to
understanding.
It's obvious that the first lot of numbers represent the total memory
(256MB), but I'm still not understanding the second lot of numbers.
"16mx8=128Mbits" Is this bandwidth or something? And I'm not sure I
follow when you say the first module would use 256Mbit chips, as I
took the second example to mean that the first module would use
8x16bit chips on one side.
Thanks again,
Dash

==============
Posted through www.HowToFixComputers.com/bb - free access to hardware troubleshooting newsgroups.

Dash wrote:

steven67@wrote:
32M x 64 bits, equals 2048Mbits/256MBytes. 32Mx64 indicates a
non-parity 256MB DIMM. 32Mx72 would
indicate an ECC 256MB DIMM.

The second 256MB module, with sixteen 16Mx8 (16M x 8 bits equals
128Mbits) chips is the type needed
for your motherboard. The first 256MB module probably uses eight
256Mbit chips, and would not be
supported by your motherboard.

Thanks for that! Maybe I'm being dumb, but I'm only half way to
understanding.
It's obvious that the first lot of numbers represent the total memory
(256MB), but I'm still not understanding the second lot of numbers.
"16mx8=128Mbits" Is this bandwidth or something? And I'm not sure I
follow when you say the first module would use 256Mbit chips, as I
took the second example to mean that the first module would use
8x16bit chips on one side.
Thanks again,
Dash

..


Each chip is 16Mx8, for a capacity/density of 128 million bits. Eight 16Mx8 chips can be used to
build a single-sided 128MB DIMM. Sixteen 16Mx8 chips can be used to build a double-sided 256MB DIMM.

Your older motherboard supports memory chip densities up to 128Mbits. Most, recent 256MB DIMMs user
higher density chips. The first 256MB module that you listed, probably has eight 32Mx8 (256Mbit)
chips on one side.

Thanks for that.
I think I get it now. Much appreciated!
Dash

==============
Posted through www.HowToFixComputers.com/bb - free access to hardware troubleshooting newsgroups.