At first glance screensavers and PC power management systems seem like an unlikely combination of topics but this week's Boot Camp is concerned with what your computer does, when you are not using it.

It's not as straightforward as you might think. Even when your PC is apparently switched off things are still happening inside the box. The internal 'real-time' clock (RTC) on the motherboard runs all the time, it is powered by a backup battery that keeps it going for months, years in some cases, even if the machine is disconnected from the mains supply. Some PC motherboards have BIOS (basic input output system) programs that continue to operate in the background when the PC has been fully shut down. One option is to monitor the modem or serial port, if an incoming call is detected the PC will be booted up, to receive faxes or voice messages.

Windows PCs can be programmed to do a variety of things when left idle. The intention is to lower energy consumption but there's a useful spin-off, switching things off when they're not being used, and that's a reduction in wear and tear on mechanical and electronic components. Desktop PCs and monitors typically consume between 50 and 100 watts when operating normally, you can take it as read that a great deal of energy is wasted every day by tens of millions of PCs around the world sitting around doing nothing. There's also the knock-on effect of the heat generated by all those PCs, forcing office air conditioning systems to work harder than necessary. Laptop and portable PCs also need to conserve power, but for slightly different reasons, to improve battery-running times and reduce the time it takes to get the PC up and running.

Screensavers have only a minor role to play in energy conservation they were originally developed to prevent screen 'burn-in'. This happens when CRT (cathode ray tube) monitor displays a bright static image for prolonged periods. Eventually an image is permanently burnt into the phosphor coatings on the inside of the screen. It's much less of a problem nowadays and screensavers are largely cosmetic since power management systems will switch monitors off when they're not in use. Windows users also tend to switch between applications fairly frequently and modern CRTs are less prone to screen burn and better lighting and anti-reflective coatings mean we can work with lower screen brightness levels.

Most recent PCs have two points of access to their power management systems. The first can be found in the BIOS program. This has settings to turn off the hard disc and power down the monitor after a pre-set period, and switch them back on again when it detects activity, such as mouse movement or keyboard actions. The range of options varies and depends on the type and age of the motherboard and processor, the hard disc drive and the monitor. To access the BIOS set-up menu look for on-screen messages immediately after boot up or refer to your PC or motherboard manual.

The second layer of power management features are embedded in Windows 95 and 98 and operate in collaboration with the PC's BIOS. The settings can be found on the Control Panel (Start > Settings). Broadly speaking Windows provides up to three power saving modes, depending on the PC hardware. The lowest level is to leave the CPU and any programs running but to put the monitor into low-power standby and switch off the hard disc drive. The second level puts the CPU into an idle state, it is still operating but running programs are suspended. In level three the PC goes into a condition known as hibernation, programs are suspended, the CPU virtually shuts down and data is saved to the hard disk. In all cases the PC can be woken up by tapping a key or moving the mouse, the time it takes to restore normal operation depends on the power save mode, typically from a second or two in level one, to between 10 and 20 seconds for level 3.

In order for a monitor to automatically switch to standby mode it must conform to the VESA (Video Electronics Standards Association) DPMS (display power management system) signalling system and be EPA (Environmental Protection Agency) Energy Star compliant. Nowadays almost all monitors (CRT and LCD) adhere to these protocols. When a monitor is connected to a PC it tells the BIOS and Windows about its power saving features and the appropriate options are included on the power management menus.

It is usually easier to set up power management from within Windows. The first step is to select the type of PC from the Power Scheme menu; there are usually three choices. Always On, where no power saving features are selected, Home/Office Desk, and Portable/Laptop. Depending on the choice the available options will be displayed below. Choose times that suit your working patterns, try to achieve a balance that will stop the machine from turning and off more than a few times each day since repeated on/off cycles can shorten the working lives of some components. If your PC has a full set of power management facilities you should get manual Suspend and/or Standby in addition to the normal shut-down options on the Start menu. These are worth using when finishing work at the end of the day, however Windows can become cluttered with programs using memory resources, which can slow it down, so it's a good idea to go through a full shut-down and re-boot every two or three days, to refresh the system.

Next week – Shareware Selection '99




Central Processor Unit – the main microprocessor chip in a PC


Liquid crystal display – flat panel display used on laptop and portable PC and now available for desktop machines. LCD monitors consume far less power than CRTs and generate no harmful emissions


The main circuit board inside a PC containing the CPU and its support circuitry, with sockets for memory cards and the sound, video and input/output 'daughter boards'



After Windows has finished loading other programs and applications may load automatically. These can cause problems if they become corrupted or are not removed properly, in which case you might want to prevent them starting in future. There are three locations in Windows 95/98 from where these programs are loaded.

The first is the StartUp group, right-click the Start button then Open, select the Programs icon, double-click to open and double-click on the StartUp icon. You can safely delete any of the shortcut icons shown.

Number two is a system file called Win.Ini. Select Run on the Start menu and type in 'sysedit'. Click on the Win.ini window and look under the '[windows]' entry, (at or close to the top of the file) for programs listed after 'load=' and 'run='. You can remove references to programs here but be warned that Win.ini is a critical file so do not tamper with it unless you know what you are doing and have made a backup.

The third location is the Windows Registry. Once again do not fiddle around unless you have made a backup first and are confident of your abilities. Click Start then Run and type in 'regedit'. Click on the plus sign next to HKEY_LOCAL_MACHINE, then work your way down the directory tree clicking on the plus signs next to: SOFTWARE, Microsoft, Windows, CurrentVersion and Run. Entries can be removed by right-clicking on the relevant icon and selecting Delete.

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