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Windows XP hints and tips

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Processor scheduling part 1

There is a lot going on in Windows, even when it is not doing anything! For example, there are lots of background services that you never see, but are busy working away, a firewall, anti virus, anti spyware, and so on. Then when you run a program Windows has to divide the processor's time between the background tasks and the foreground program you are using. How much processor time should be dedicated to foreground and background tasks?

Click Start and then right click My Computer and choose Properties. Select the Advanced tab and click the settings button in the Performance section. Select the Advanced tab in the next dialog that aooears and then in the Processor Scheduling section you'll see two options: Programs and Background Services.

If you choose Programs then foreground programs (the ones you work with) get three times as much processor time than background programs. If you choose Background services then foreground and background programs get equal processor time.

So which setting is best? You should try both. Choose programs and use your PC for a day or two, then choose Background services and see if your PC is better or worse.

Processor scheduling part 2

If you read the last tip you'll be aware of the ability to change the amount of time the processor spends on foreground and background programs. Changing the setting actually changes a value called Win32PrioritySeparation in the registry. Click Start, Run and enter regedit to open the registry editor. In the left-hand pane navigate to HKEY_LOCAL_MACHINE\ SYSTEM\ CurrentControlSet\ Control\ PriorityControl and on the right you'll see Win32PrioritySeparation. Double click it.

Windows reads this as six binary digits and splits it into three blocks of two: XX XX XX. Now binary numbers can be 0 or 1, so each XX can be 00, 01, 10 or 11. The highest two bits (the left two) determine whether each processor time allocation is relatively long or short. The middle two bits determine whether the length of the processor time varies or is fixed. The lowest two bits (the right two) determine whether the threads of foreground processes get more processor time than the threads of background processes each time they run. Technical people should take a look at this article on the Microsoft website.

At the end of the article it says that the value of Win32PrioritySeparation should be 100110 for Programs and 011000 for Background services (see previous tip). However, if you check the value in the registry you may find that it's set to 2. Load Windows Calculator, switch to scientific mode, select binary and enter 100110. Select Hex and you'll see the value 26. Double click Win32PrioritySeparation, make sure Hexadecimal is selected and enter 26 to give Programs priorities. Enter 011000 into Calculator in binary, switch to Hex and you'll see it's 18, so for Background services to be given priority, enter 18 for Win32PrioritySeparation. Are these values better? Try them and see.

Use System Restore

System Restore is a useful tool in certain circumstances and it enables you to 'turn back the clock'. Windows and the software you install stores lots of configuration settings in the registry and other places. Mostly this is useful, but occasionally you might install something that causes problems. For example, you might install an update to a program, such as a video card driver, that conflicts with existing software or hardware. System Restore is a way of putting things back the way they were before you installed it.

If you have installed some software and it is causing problems, uninstall it in the usual way, for example, using Add or Remove Programs in the Control Panel, and then use System Restore. Click Start, All Programs, Accessories, System Tools, System Restore. Select Restore my computer to an earlier time, and then click the next button. You'll see a calendar and some of the dates are in a bold font. These are the days on which Windows has made a backup. Select one of these days and select one of the restore points listed (there may be just one or several). You should select a restore point on a date before you started to have problems, then click Next. Just follow the prompts and Windows will restart and apply the backed up settings.

Adjust System Restore's space requirements

System Restore backs up important Windows settings and stores the backups on the hard disk drive. A certain amount of disk space is reserved for System Restore and you should check the amount because it may be too large or too small. If it is too small then Windows won't be able to store many backups and your System Restore options are limited if you have a problem. If it is too large then lots of unnecessary disk space is used.

Click Start, then right click My Computer and select Properties. Click the System Restore tab and you will see the settings for each disk drive (many people only have one drive, but it works for multiple drives). Select a disk and click Settings to see how much space is being used. If the slider is all the way to the left (200Mb) then too little space is reserved for System Restore and only one or two backups will be made. At the Max end of the slider the amount of space depends on the size of the disk and with a 500Gb disk this will be 60Gb, which is way too much. System Restore needs no more than 3 or 4Gb, so drag the slider back and forth until it is around 4Gb. Click OK and OK again to close the dialogs.

Turn off System Restore

System Restore is useful because it enables you to recover from problems by putting things back the way they were, so why would you want to turn it off? One reason is to clear your computer of viruses and spyware. If your computer becomes infected, Windows might perform one of its regular backups and the virus or spyware get's backed up too. It'll be stored as a System Restore restore point.

Although you can clean up the computer with anti virus and anti spyware tools, if you ever use that restore point, you'll infect the computer again from the backup. You should turn off System Restore, clean the virus of spyware from the computer, and then turn System Restore back on again. This has the effect of removing all the restore points, but who knows which ones were infected? Windows will start making new restore points now that the system is clean again.

Click Start, then right click My Computer and select Properties. Click the System Restore tab and tick the box labelled Turn off System Restore on all drives.

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