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In the olden days of DOS, a computer could only run one program at a time. Programs had to be written to fit in the available 64 K (or whatever) of memory. Otherwise, the program wouldn’t fit, wouldn’t run, and would just end up displaying the message Not Enuf Memory on the screen (yes, I know it’s spelled “enough,” but the message showed “enuf”). In the Windows world, you can load up and run almost as many programs as you want. But, if you tried to start a new program when you already had some running, and RAM was already full, or near full, you’d get a “Not Enuf Memory” error. Computer scientists realized you could avoid that error by using a small portion of the hard disk as extra memory, called virtual memory, to handle the overflow. The CPU can’t get information to and from the hard disk as fast as it can to and from RAM. That’s because the hard disk is a mechanical device with moving parts. The disk spins around, and the drive head moves about the disk to read and write data. But even though the hard disk isn’t quite as speedy as RAM, better to let things slow down a little than to just stop dead and announce “Not Enuf Memory.” All modern computers actually have two types of memory. There’s the speedy physical memory (RAM) that’s actually on the RAM chips installed on your computer’s motherboard. And there’s the slower virtual memory, stored on hard disk, used as a backup to handle anything that goes beyond the capacity of the physical memory. A system’s total memory is the sum of its physical and virtual memory.

The amount of RAM shown on the General tab of the System Properties dialog box is the amount of physical RAM in your system.

The area on the hard disk that’s used as virtual memory is often called a paging file, because information is swapped back and forth between physical and virtual memory in small chunks called pages. When you fill up both your physical memory and virtual memory, the computer doesn’t just stop dead in its tracks and display “Not Enuf Memory.” Rather, it displays a message in advance, warning that you’re about to run out of virtual memory and suggesting that you make room for more. Because the virtual memory is just a tiny paging file on the hard disk, you can easily add more just by increasing the size of the paging file. You don’t have to buy or install anything. To the contrary, the only way to increase physical memory is to buy and install more RAM. As you may have guessed, the Change button under Virtual memory in the Performance Options dialog box is the place you go to do that. When you click the Change button, you’ll see the options. In almost all cases, it makes sense to choose the top checkbox labeled “Automatically manage paging file size for all drives” to allow Windows to adjust the page file. If you don’t want Windows to manage the page file for you, your main options in the “Paging file size for each drive” area of the Virtual Memory dialog box are

- Custom size: You choose where you want to put your paging file(s), their initial size, and maximum size.

- System managed size: Tells Windows to create and size the paging file automatically for you.

- No paging file: Eliminates the paging file from a drive. Not recommended unless you’re moving the paging file from one drive to another.

If you have multiple hard drives, you can get the best performance by using the least busy drive for virtual memory. For example, if you have a D: drive on which you store documents, it may be better to use that, rather than the C: drive, because the C: drive is pretty busy with Windows and your installed programs. If you have multiple physical drives, you can get a little performance boost by splitting the paging file across the two drives. A single drive that’s partitioned into two or more partitions, to look like multiple drives, doesn’t count. You don’t want to divide the paging file across multiple partitions on a single drive, because that will have the reverse effect of slowing things down. If you do opt for a custom size, you can work with any one hard drive at a time. The drives are listed by letter and label at the top of the dialog box. In the example shown, all of the partitions actually reside on a single disk.

The Disk Management tool discussed in Article 47 lists hard drives by number. If you have a single physical hard drive, it will be Disk 0. If you have two physical hard drives, they’ll be listed as Drive 0 and Drive 1, and so forth.

If you don’t choose the checkbox at the top of the Virtual Memory dialog box, you’ll need to set the paging file sizes individually. For example, to move the paging from drive C: to D:, first click Drive C: at the top of

the dialog box, choose No Paging File, and then click the Set button. Then, click Drive D:, choose Custom Size, set your sizes, and click Set. The Total Paging File Size for All Drives section at the bottom of the dialog box shows the minimum allowable size, a recommended size, and the currently allocated size (the last measurement being the sum of all the Initial Size settings). The recommended size is usually about 1.5 times the amount of physical memory. The idea is to prevent you from loading up way more stuff than you have physical RAM to handle, which would definitely make your computer run in slow motion. If your computer keeps showing messages about running out of virtual memory, you’ll definitely want to increase the initial and maximum size of the paging file. A gigabyte (1,024 MB) is a nice round number. But if the computer runs slowly after you increase the amount of virtual memory, the best solution would be to add more physical RAM. If you do change the Virtual Memory settings and click OK, you’ll be asked if you want to restart your computer. If you have programs or documents open, you can choose No and close everything up first. But because the paging file is only created when you first start your computer, you’ll eventually need to restart the computer to take advantage of your new settings.

Windows ReadyBoost uses flash memory, rather than your hard disk, for the paging file. This allows programs to get disk data more quickly, providing a faster, more fluid computing experience.

Windows Vista  Using Windows ReadyBoost

Historically, PCs had two ways to store data: memory and the hard disk. Memory (RAM) is very fast. But it’s volatile, meaning everything in it gets erased the moment you shut down the computer. The hard disk isn’t nearly as fast. But it has persistence, meaning that it retains information even when the computer is turned off. RAM is also more expensive, and therefore scarcer than hard disk storage. For example, a computer might have less than 1 gigabyte of RAM, or maybe up to 4 gigabytes or a little more. The hard disk, on the other hand, usually holds tens or even hundreds of gigabytes of data. When you try to do things for which you don’t have enough RAM, Vista automatically uses the paging file (discussed in the previous section) to store the data that won’t fit in RAM. Many programmers also use the paging file intentionally to conserve RAM. So the paging file can be a busy file no matter how much actual RAM you have. The downside to using the paging file is that the processor cannot move data to and from it as quickly as it can with RAM. The paging file becomes a little performance bottleneck. Prior to Windows Vista, there was no real solution to the problem. Vista is the first version of Windows to offer a real solution. It’s called ReadyBoost, and it lets you use flash memory for the paging file. For paging file operations, flash memory is about 10 times faster than a hard disk, which means ReadyBoost can get rid of many little short delays and offer a faster, smoother overall computing experience.

Contrary to some popular belief, ReadyBoost doesn’t add more RAM to your computer. It improves performance by using flash memory, rather than the hard disk, to store and access frequently used disk data. Windows Vista takes care of all the potential problems that using flash memory for disk data might impose. For example, it keeps the actual paging file on the disk in sync with the copy on the flash drive. So if the flash memory suddenly disappears (as when you pull a flash drive out of its USB slot), there’s no loss of data. Vista even compresses and encrypts the data on the flash drive using government-strength AES encryption. If someone steals a ReadyBoost flash drive from your computer, they will not be able to read data from it to steal sensitive information.

There are basically three ways to get ReadyBoost capabilities in your system. One is to use a hybrid hard disk drive, which puts the flash memory right on the drive. Another is to have ReadyBoost capability on the computer’s motherboard. If you have neither of those, the third approach is to use a USB flash drive for ReadyBoost. This is a small device, usually small enough to fit on a keychain, that you just plug into a USB 2.0 port on your computer. Not all flash drives are ReadyBoost capable. They vary greatly in their capacity and speed. Vista will only use a flash drive for ReadyBoost if it makes sense to do so. A flash drive that wouldn’t help with performance can’t be used for ReadyBoost. When it’s ReadyBoost performance you’re after, a 4 GB flash drive with fast random I/O capability is your best ally.

Four gigabytes is the maximum size for ReadyBoost. But because of compression, you actually get about double the drive’s capacity. So a 4 GB flash drive really gives you about 8 GB of ReadyBoost storage. If you already have a USB flash drive, and want to see if it’s ReadyBoost capable, just plug the drive into a USB slot. ReadyBoost requires that you use a USB 2.0-compliant thumb drive. Anything preceding USB 2.0 is too slow to work as a ReadyBoost device.

If you want to use the device as virtual memory, select the Speed up my system option. After you’ve selected that option, the properties for the removable disk will pop up . You can also bring up that dialog box by opening your Computer folder, right-clicking the drive’s icon, and choosing Properties. Select the Use this device option and then you are able to set the amount of space for ReadyBoost. By default, Windows sets the value to the recommended amount and also lets you know that the space you allocate won’t be available for general use. When you’ve set your value, click the OK button. ReadyBoost works by copying as much of the information as possible from virtual memory to the USB thumb drive. There is still a copy of all of the information within virtual memory; the system now knows to look at the ReadyBoost device first. If the system can’t find the information there, it will look to the real virtual memory located on your hard drive. By keeping the original copy on your hard drive, you’re able to remove your USB thumb drive without disrupting the computer. Don’t expect to see everything suddenly run faster with ReadyBoost. Its benefits might not be immediate. Remember, the main purpose of ReadyBoost is to eliminate the short delays you might experience when loading certain programs, switching among open programs, and other activities that usually involve a paging file. With time, you should experience quicker response times in those areas. You might even find your computer starts more quickly because it takes less time to load programs at startup.

Trading pretty for performance

All the fancy stuff you see on your screen while using Windows comes with a price. It takes CPU resources to show drop-shadows beneath 3D objects, make objects fade into and out of view, and so forth. On an old system that has minimal CPU capabilities and memory, those little visual extras can bog the system down. The Visual Effects tab of the Performance Options dialog box lets you choose how much performance you’re willing to part with for a “pretty” interface. As you can see the Visual Effects tab gives you four main options:

- Let Windows choose what’s best for my computer: Choosing this option automatically chooses visual effects based on the capabilities of your computer.

- Adjust for best appearance: If selected, all “pretty” effects are used, even at the cost of slowing you down.

- Adjust for best performance: Choosing this option minimizes “pretty” effects to preserve overall speed and responsiveness.

- Custom: If you choose this option, you can then pick and choose any or all of the visual effects listed beneath the Custom option. To get to Visual Effects Performance Options from the desktop, click Start, type perf, and click Performance Information and Tools. Then click Adjust visual effects in the left column. How you choose options is entirely up to you. If you have a powerful system, then the visual effects won’t amount to a hill of beans. So, there’s no need to back off on the visual effects. But if your computer isn’t immediately responsive to operations that involve opening and closing menus, dragging, and other things you do on the screen, eliminating some visual effects should help make your computer more responsive.