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Understanding Available Memory - 19 Oct 2005

Understanding Available Memory

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1. Commentary
- Understanding Available Memory

2. Reader Challenge
- September 2005 Reader Challenge Winners
- October 2005 Challenge

3. News & Views
- Yahoo!, Microsoft Link IM Services

4. Resources
- Tip: Using EFS to Encrypt Files and Folders
- Featured Thread: Windows XP home shuts down on boot

5. New and Improved
- One-Click PC Maintenance
- Tell Us About a Hot Product and Get a T-Shirt!

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==== 1. Commentary: Understanding Available Memory ====
by David Chernicoff, [email protected]

My recent column about memory concerns with a desktop system upgrade (see the URL below) generated a lot of reader response, most in the "please follow up on this issue" vein. But a surprising number of readers asked questions that made it clear they don't understand how a computer and OS utilize memory.

From the OS's perspective, the amount of memory available to the OS is the amount that the hardware reports is available, regardless of how much memory is physically installed an enumerated. That was the issue that generated my original concern: a 4GB system that reported only 3200MB of available memory to the OS.

I found the answer to my original question in the support documentation for the motherboard: "On a system with 4GB of system memory installed, it is not possible to use all of the installed memory due to system address space being allocated for other system critical functions." I knew that system resources took memory space but was surprised by the 750MB being reserved for PCI Express features. A few readers told me that their server-class systems had motherboard settings that let them move the PCI memory space above the 4GB line; that feature isn't available in the family of desktop motherboards I'm using.

Readers also pointed out that if I use 64-bit Windows, I can map the system resource memory to another location so that the physical memory will be available for applications. I plan to install 64-bit Windows as an alternate OS on this computer, but none of the applications I use on a daily basis are available yet in native 64-bit versions.

But what I want to address this week is a clear misunderstanding about how system memory works. I received several email messages that asked question such as, "Does this mean that I can't use PCI Express on a system that has only 512MB of RAM?" or "Will I only have 256MB of useable memory in a 1GB system?"

Neither of those situations is a problem. The system resources aren't taking away large chunks of installed memory; the system resources reserve memory space at the top of the 4GB memory range addressable by a 32-bit processor. If this system board has less than 4GB of physical memory installed, the memory use is pretty much invisible to the user. Only when a user has 4GB of physical memory installed does the problem become obvious.

The computer that I used to generate this column reports 896MB of memory reserved for system resources (down from 1126MB after a BIOS update) and 3200MB of memory available to the OS. This means I paid for a fourth 1GB bank of RAM that's effectively unusable; the system would have the same performance and virtually the same OS memory if I had installed only three banks of 1GB memory. This problem doesn't affect systems with 3GB of memory or less. It will be a concern only to those of us who find a need for the maximum amount of memory the system claims to support. The reality of the situation is that with a 32-bit OS, motherboards that support PCI Express and can't map memory above 4GB, won't have the full 4GB addressable range of memory available to applications.

Troubleshooting a Memory Problem During a System Upgrade


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==== 2. Reader Challenge ====
by Kathy Ivens, [email protected]

September 2005 Reader Challenge Winners
Congratulations to the winners of our September 2005 Reader Challenge. First prize goes to Brian Frahm of Arizona. He wins a copy of copy of "Windows XP Hacks, Second Edition" (O'Reilly Publishing). Second prize, a copy of "Home Networking for Dummies, Third Edition," goes to Virginia McDevitt of California.

October 2005 Reader Challenge
Solve this month's Windows Client challenge, and you might win a prize! Email your solution (don't use an attachment) to [email protected] by October 26, 2005. You must include your full name and street mailing address (without that information, we can't send you a prize if you win, so your answer is eliminated, even if it's correct).
I choose winners at random from the pool of correct entries. I'm a sucker for humor and originality, and a cleverly written correct answer gets an extra chance. Because I receive so many entries each month, I can't reply to respondents, and I never respond to a request for a receipt. Look for the solutions to this month's problem at on October 27, 2005.
Incidentally, many IT directors use the Reader Challenge as a trivia game in their IT department and have written to ask me for old Reader Challenge questions (this column has appeared in print and in UPDATE newsletters for many years). I don't keep them, but you can search the site, which archives columns.

The October 2005 Challenge:

A consultant who specializes in peer-to-peer networks for small businesses called to ask for help solving a puzzle he'd encountered. He explained that he'd switched one of his clients to a domain (to take advantage of client server technology offered by the client's new accounting application). Everything was working well. Last week, he went into the client's office early in the morning to add hardware to the domain controller (DC). He had just finished his work, and was about to restart the DC, when one of the client's employees walked into the office where the DC resides. The employee said, "I'm glad you're here, I can't print." The consultant replied, "You can't print? You mean you can't log on to the network, right?" The employee replied, "Oh, the computer started fine and logged on to the domain fine, and I've been working on documents, but they won't print. I turned on the printer, but Windows displays an error message that it can't access the printer."

The consultant wanted to know how a user could start Windows and join a domain when the DC was down? Can you answer his question?

==== 3. News & Views ====
by Paul Thurrott, [email protected]

Yahoo!, Microsoft Link IM Services
In a bold but widely anticipated move, Microsoft and Yahoo! announced this morning that they will be linking their IM systems, allowing MSN Messenger users to chat with Yahoo! Messenger users. The companies say that this interoperability should be available by mid-2006. Read the entire story at the following URL:

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Tip: Using EFS to Encrypt Files and Folders
(contributed by David Chernicoff, [email protected])

When I talk to clients and users about computer security, I often suggest that making use of the Encrypting File System (EFS) support with NTFS is a simple way to add additional security to folders and documents on users' computers. However, many users are put off; they want a simpler point-and-click method for encrypting or decrypting files instead of having to open the Properties menu and drilling down to the file/folder encryption feature. You can add the Encrypt/Decrypt command to a folder's right-click context menu by performing the following registry change:
1. Open the registry editor.
2. Navigate to the HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced registry subkey.
3. In the right pane, right-click and add a new REG_DWORD called EncryptionContextMenu.
4. Set the Decimal Value of the new entry to 1.
5. Exit the editor.

A new command--Encrypt or Decrypt, depending on the state of the file--will appear on the context menu.

Featured Thread: Windows XP Home Shuts Down on Boot
Forum user ec1shelly is trying to troubleshoot a friend's computer that no longer boots correctly. Read about the problem and offer your help at the following URL:

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