Re: Adding RAM to WS II

Mon, 17 May 2004 07:12:03 -0700

You're right, it brings back to memory all that A+ stuff I learned... they don't teach you a whole lot on how Macs work though, that was disappointing because its real interesting. Know any good links for how the hardware in a Mac works? What kind of controller does the motherboard use to access memory, does it address the same way a PC does? North-bridge/south-bridge, are these relevant? Curious more than anything else, no explanation needed, just a link, but perhaps other posters would like to know if someone has the time. Thanks!

Mike

On Thursday, May 13, 2004, at 08:37 PM, Nils wrote:

You guys are getting closer..

There are 2 issues here.  One at a time.

First, a WallStreet II runs a 66MHz System Bus. That means that you can run
PC66, PC100 or PC133 memory. The rating shows the speed that the memory
has been certified to run at.

A piece of PC66 memory run on a 100MHz system but _might_ work. But when it
was tested at the factory, they guarantee that it will run correctly and
error free at 66MHz.

The answer is, get whatever you want. PC66, PC100 or PC133 will work correctly.

Second, as for the "chip density". Yes, this is an issue. And is often not on
a sticker attached to the memory module.

Here is an example...

If you had a 168pin (Dual In-Memory Module), it has 4 chips and the label
says 8Mx32. It would break down like this...

Chip Density :
8 (chip depth in millions) x 32 b (chip width in bits) = 256 Megabit (Mb)

   256 Megabit (Mb) x 4 (number of chips) = 1024 Megabit (Mb)

   Module Density :
   1024 Megabit (Mb) / 8 b (bits per byte) = 128 MegaByte (MB)

When the motherboard for the WSII was designed, the memory controller used
knew about different sizes of memory chips available at the time of production.
So the sizes that it knew, it is able to address correctly.

Now, since I don't have any 256MB modules in my WS right now, I can't tell
you this for sure. But I'm going to take a guess..

I'm thinking that the memory controller doesn't know how to address a memory
chip with a depth greater than 8 million bits.

So it might be able to correctly access an 8Mx32 chip, but not a 16Mx16 chip.
Both of those sizes are 256Mbit, but if the controller doesn't understand how
to read a chip depth greater than 8 million bits, it will address the memory
as an 8Mx16.

If I'm right. This should explain why some 256MB modules show up as 128MB
on older laptops..

Chip Density :
8 (chip depth in millions) x 16 b (chip width in bits) = 128 Megabit (Mb)

   128 Megabit (Mb) x 8 (number of chips) = 1024 Megabit (Mb)

   Module Density :
   1024 Megabit (Mb) / 8 b (bits per byte) = 128 MegaByte (MB)

So, what you will want to look for is a 256MB module with 8Mx32 chips.

I REALLY hope I'm right. It'd suck if I did all this reading/math to find out
that I'm way off base.

Btw, this page is where I found all the relevant information.

http://www.kingston.com/tools/umg/umg04.asp

-nils
(250MHz WS, 416MHz Beige G3, 200MHz PB1400)

--
G-Books is sponsored by <http://lowendmac.com/> and...

Small Dog Electronics http://www.smalldog.com | Refurbished Drives |
-- Check our web site for refurbished PowerBooks | & CDRWs on Sale! |

      Support Low End Mac <http://lowendmac.com/lists/support.html>

G-Books list info:      <http://lowendmac.com/lists/g-books.html>
  --> AOL users, remove "mailto:";
Send list messages to:  <mailto:[EMAIL PROTECTED]>
To unsubscribe, email:  <mailto:[EMAIL PROTECTED]>
For digest mode, email: <mailto:[EMAIL PROTECTED]>
Subscription questions: <mailto:[EMAIL PROTECTED]>
Archive: <http://www.mail-archive.com/g-books%40mail.maclaunch.com/>



---------------------------------------------------------------
The Think Different Store 
http://www.ThinkDifferentStore.com
---------------------------------------------------------------





--
G-Books is sponsored by <http://lowendmac.com/> and...

Small Dog Electronics    http://www.smalldog.com  | Refurbished Drives |
-- Check our web site for refurbished PowerBooks  |  & CDRWs on Sale!  |

     Support Low End Mac <http://lowendmac.com/lists/support.html>

G-Books list info:      <http://lowendmac.com/lists/g-books.html>
 --> AOL users, remove "mailto:";
Send list messages to:  <mailto:[EMAIL PROTECTED]>
To unsubscribe, email:  <mailto:[EMAIL PROTECTED]>
For digest mode, email: <mailto:[EMAIL PROTECTED]>
Subscription questions: <mailto:[EMAIL PROTECTED]>
Archive: <http://www.mail-archive.com/g-books%40mail.maclaunch.com/>



---------------------------------------------------------------
The Think Different Store 
http://www.ThinkDifferentStore.com
---------------------------------------------------------------

Reply via email to