|Aptiva TechDoc #10011
Last updated 11/08/99
Graphics Without Pain
by Brian Livingston
Windows 95 is notorious for its intermittent, inexplicable crashes, particularly on older systems. To add insult to injury, the error message you receive (if you even get one) may not pinpoint the root of the problem. In many cases, the culprit is your graphics driver. If this situation sounds familiar, here are some troubleshooting tips that can help.
The Acceleration Box
In the Advanced Graphics Settings dialog box, there are four levels of graphics acceleration: None, Basic, Most, and Full. As you move the slidebar, the description for each setting changes accordingly. To get to this dialog box, right-click on My Computer, then select Properties, the Performance tab, and the Graphics button. If you change the graphics-acceleration setting here, you must restart Windows so the change will take effect.
To use the information described in this column, you'll need to know what type of display adapter your system is using. You can find this information in the Device Manager, under the Display adapters category (or in the Display Properties sheet).
In the System Properties dialog box, go to the Device Manager tab and make sure the View devices by type radio button is selected. Within this list of devices, click on the plus sign to the left of the Display adapters icon to reveal your adapter type, such as S3 Trio32/64 PCI. Also, when you boot your system, and before the Windows logo displays, you may see information about the type of display adapter and the BIOS revision number. In some cases, Windows 95 incorrectly identifies graphics hardware within the same family, by identifying a particular card as a different (often older) model from the same manufacturer or as a generic VGA card. To be absolutely sure of the type of graphics hardware, check the card itself or consult the system's documentation (if you're still using the adapter that came with the system, that is).
Windows may also make mistakes identifying your monitor. So while you're in the System Properties dialog box, verify the monitor's information as well. To do this, select the plus sign to the left of the Monitor icon. Your monitor type should be listed. If it isn't, close the dialog box, then right-click on the desktop, and select Properties from the pop-up menu. In the Display Properties dialog box that appears, select the Settings tab and choose Change Display Type. Then click on the Change button under Monitor type. You may see a Show all devices option in the bottom right-hand section of the resulting dialog; if you do, select it. Now select the appropriate manufacturer and model. If you're unsure, don't select a model name that isn't displayed somewhere on your monitor--this could damage it.
When Hardware Acceleration Doesn't
Based on compatibility testing and user feedback, Microsoft recommends different hardware-acceleration settings for systems that have intermittent, inexplicable crashes.
Sometimes changing the Hardware acceleration setting in the Advanced Graphics Settings dialog from Full to Basic, and restarting Windows, can almost completely eliminate the system's unexplainable crashes. And the change may not degrade the system's graphics performance. The fact is some of Windows' features, such as the speed of displaying a usually hidden Taskbar, are faster with the Hardware acceleration option set to Basic than with it set to Full. Apparently, using the Full acceleration setting's functions can cause problems with certain graphics chip sets and drivers.
Changing the slidebar to Most, Basic, or None may clear up some of the problems you might be experiencing. The following is a more detailed description of each of these settings.
Advanced Graphics Settings
The Full acceleration setting lets Windows send display information to your graphics adapter in the fastest, most accelerated manner. But some graphics hardware may not be able to read the information at such a rapid speed, thereby causing the "unexplainable" crashes. Primarily, this problem is due to graphics adapters that are somewhat older, such as the S3-based Diamond Stealth 32 and 64, and that conflict with modems attached to a COM4 serial port.
And when the system crashes, you won't get an error message such as "Change from Full acceleration to a lower setting," but you will get one that reads "Explorer.exe caused a General Protection Fault in Kernel32.dll." If you've been seeing this kind of message, changing to a lower acceleration setting may help and, in my opinion, may not even hurt your system's graphics performance.
The Most setting enables most acceleration functions but disables some graphics functions related to displaying the mouse pointer (or cursor). This setting disables what's known as the hardware cursor, which is a way to make your graphics adapter display the position of the mouse, and takes a processing load off your CPU.
Changing the setting to Most has the same effect as inserting SWCursor=1 in the Display section of your SYSTEM.INI file. This is one of many cases in which Windows 95 uses settings in SYSTEM.INI to set the proper mode for various devices. And setting SWCursor=1 in SYSTEM.INI has the same effect as loading the real mode Microsoft Mouse driver in the AUTOEXEC.BAT file with the /y switch. When AUTOEXEC.BAT includes /y (which stands for yes) on the MOUSE.EXE line, the hardware cursor is disabled for the real mode driver. (If you never use your mouse outside Windows, you have no need for the real mode Microsoft Mouse driver.) Typically, the Most setting is used with some Western Digital and S3-based graphics adapters.
The Basic setting adds the line MMIO=0 to the Display section of your SYSTEM.INI file, as well as the SWCursor=1 line (discussed above), thereby disabling memory-mapped input/output on S3-compatible graphics adapters. The line SafeMode=1 is added to the Windows section of your WIN.INI file, which enables a fairly safe type of acceleration involving small screen patterns (or bit-block transfers). The Basic setting is useful primarily for some models of graphics hardware that are based on S3 chip sets.
The None setting eliminates all of the acceleration "tricks" that Windows uses. As with the Most and Basic settings, setting acceleration to None writes into your SYSTEM.INI and WIN.INI files. But it does so with one distinction: The None setting adds the line SafeMode=2 instead of SafeMode=1 to WIN.INI, which forces Windows to draw to the screen using its own functions, rather than relying on the graphics display driver.
Brian Livingston is coauthor with David Straub of Windows 95 Secrets and author of three other books on Windows, all from IDG Books.
The Worst Offenders
Some of the problems we've discussed affect certain hardware. The following exhibit such symptoms.
S3-Based Graphics Adapters
Some adapters based on the S3 graphics chip set (such as the Diamond Stealth 32 and 64 and Orchid Technology's Fahrenheit 1280) may need a lower acceleration rate than Full acceleration and may conflict with modems attached to a COM4 serial port. One symptom of this: The lights on an external modem flash when you move your mouse or initiate any hard disk or network activity.
The cure for problems with S3-based adapters is to use a level of acceleration that's lower than Full and to move modems from COM4 to a lower-number serial port, such as COM1, COM2, or COM3. Or you can simply change the Display Properties to a graphics mode of 256 colors or fewer.
Adding the line HighColor=15 to the Windows section of the WIN.INI file corrects a problem with incorrect color display in modes that support 16 colors per pixel (or high color).
Microsoft recommends that you insert the line TrueColor=24 into the Display section of SYSTEM.INI to obtain true 16.7-million-color support.
If you installed Windows 95 over Windows 3.1 while running Setup from a DOS prompt, it will incorrectly use its own standard VGA driver. Microsoft recommends that you copy the Viper files from the \Drivers folder on the Windows 95 CD-ROM and use the Diamond Viper setup program to install them.
ATI Mach 8, 32, 64
Microsoft says that you must use the ATI INSTALL.EXE program to configure your adapter and your monitor to correctly handle high-resolution modes.
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