simms

[hoss]

In my computer serving course at the university, we were asked the question as to why we would neeed simms to run in pairs. Could anyone give me a straight answer on this, noone in my class knows and out insructor wants to see if we will actually be able to find out. i appreciate everyones feedback.


Hoss

[YODA74]

hoss, Welcome to PC Guide, Try a www.google.com (http://www.google.com) search on this you should find what you seek.We do not do school work here,need to understand a search engine and how they work before going on to computers.If we answered
your question then it would not be home work and it would defeat the purpose of learning to take control of the situation. Sorry appreciate your honesty though a lot that we see try to sneak in questions and you know darn well that it is a school assighnment.And they try to hide the fact that it is home work. we sure will help you in your personal computer problems though.

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Treading,Troden,Trails
HERE (http://www.davematthewsband.com)

[This message has been edited by YODA74 (edited 12-02-2001).]

[YODA74]

hoss I'm gonna break my own rule and give you partial answer the rest is for you to find (Yes I'm Bored thats why) http://www.PCGuide.com/ubb/biggrin.gif


The type of board and connector used for RAM in desktop computers has evolved over the past few years. The first types were proprietary, meaning that different computer manufacturers developed memory boards that would only work with their specific systems. Then came SIMM, which stands for single in-line memory module. This memory board used a 30-pin connector and was about 3.5 inches by .75 inches (about 9 centimeters by 2 centimeters) in size. In most computers, you had to install SIMMs in pairs of equal capacity and speed. This is because the width of the bus is more than a single SIMM. For example, you would install two 8 megabyte (MB) SIMMs to get 16 megabytes total RAM. Each SIMM could send 8 bits of data at one time while the system bus could handle 16 bits at a time. Later SIMM boards, slightly larger at 4.25 inches by 1 inch (about 11 centimeters by 2.5 centimeters), used a 72-pin connector for increased bandwidth and allowed for up to 256MB of RAM.




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Treading,Troden,Trails
HERE (http://www.davematthewsband.com)

[rond36]

Also when the standard went from SIMMs (single inline memory moduals) to DIMMs (duel inline memory moduals) the DIMMs nolonger need to be installed in pairs because DIMMs have a 16 bit wide bus (more or less 2 SIMMs on the same PCB) this is why if you look at the results of the POST you will see 6 memory locations for 3 DIMM slots (0 & 1 = slot 1) (2 & 3 = slot 2) (4 & 5 = slot 3) if you have 2 slots 4 memory locations

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Alright who messed it up this time!

[iisbob]

Seems like these guys pretty much covered it.

I'll add this to the previous posts;

Original memory ( address ) Buses were as stated only 8bits wide, then they went to 16, then 32-with the advancement of the system memory bus came the need to change the pin outs on the memory sticks themselves to keep up with the additional wires in the memory bus ( each wire transmits 1 bit-more wires=more bits ) So the original systems used 30 pin SIMMS -two together as stated to equal 16 bit bus, then 72 pin Simms ( which were 16bit capable, but now you had 32 bit memory buses )in pairs, then finally DIMMS which are 32 bit capable so they could run as a single unit on the 32 bit memory ( address ) bus.

Interesting note is that currently the data and control buses are 64 bit and the memory bus is still 32 bit ( except on some server boards ), this is for compatability with OS"s and CPU's which are still only 32 bit program-or 4 word size; however there is a 64 bit XP in the offering and there will soon be atandard 64 bit CPU's available-this means faster/more data processing power available. The rub is is that 99% of all software is written in 32 bit code to comply with today's systems ( OS and hardware ), so even though they would run on a 64bit system-you wouldn't see any performance increase. Give it a few years and you'll wonder how we ever managed to compute on these current " dinosaurs " http://www.PCGuide.com/ubb/smile.gif

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iisbob
""I was gratified to be able to answer promptly, and I did. I said I didn't know."
Mark Twain

[fixrupr]

hoss,

Didn't your mother teach you to say "thank you"? http://www.PCGuide.com/ubb/frown.gif

Well, I will then, Thanks! I think your combined explanation was appreciated by many even if not acnowledged properly.
THANKS!