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Maximize Conventional Memory Under Windows 95

Conventional memory is much less important to Windows 95 users than it is to users of DOS, because Windows 95 programs can use all of the extended memory available on the machine instead of trying to squeeze into 640 KB. However, since most people still run DOS programs under Windows 95, they need to still worry about having enough conventional memory to let DOS applications work properly.

One of the nice things about Windows 95 is that it loads drivers into extended memory--drivers that DOS has to squish into conventional or upper memory areas. Since extended memory is large, this means far fewer concerns with how much space various drivers are using. However, when you boot Windows 95, you are really booting a form of DOS and then running Windows 95 on top of it (no matter what Microsoft wants you to believe. :^) ) When you "Restart the computer in MS-DOS mode" (from the Shutdown menu) you are in fact just closing the Windows 95 graphical interface and dropping down to DOS. When you do this, or if you bypass loading the "true" Windows 95 program entirely, you now cannot use the extended-memory Windows 95 drivers, and you are back to using DOS conventional memory drivers. This can cause serious conventional memory problems.

Note: If you don't ever boot into DOS, you're unlikely to have problems with Windows 95 conventional memory.

The first thing you should do is read the section discussing conventional memory maximization for DOS and follow those guidelines. You should find that in most cases, this will give you a good amount of conventional memory, both in an MS-DOS Prompt box under Windows 95, and also when you restart in MS-DOS mode. As long as you don't do anything too fancy in DOS mode, you should be fine.

Tip: Use this DOS command to check memory usage and the amount free: "MEM /C /P".

The one really tricky thing is Windows 95's compression driver and how to manage it. (Well, the best way is not to use compression at all if this is possible...) The DRVSPACE compression driver is large--110 KB in size--so it's difficult to handle. You have a couple of choices of how to configure loading the driver, as there is a tradeoff here:

• Maximize DOS Conventional Memory In DOS Mode: If you tell the system to load the compression driver into upper memory (by using DEVICEHIGH on the command in CONFIG.SYS that loads DRVSPACE.SYS), this will save 110 KB of conventional memory when you are running in MS-DOS mode. However, the 110 KB of upper memory will force other drivers into conventional memory, causing the free conventional memory to decrease. This is still better than leaving the 110 KB also in conventional memory. When you run "true" Windows 95, with the graphical interface, Windows will leave the compression driver in the upper memory area instead of loading an extended-memory version, so your DOS sessions in Windows 95 will have less conventional memory.
• Maximize DOS Conventional Memory In DOS Sessions: If free conventional memory is more important to you in DOS sessions under Windows 95 proper, do not load DriveSpace using DEVICEHIGH, but rather leave it in conventional memory. If you do this, and add the "/MOVE" parameter to the DRVSPACE line, then Windows 95 will automatically move the driver to extended memory when the graphical interface starts, thus saving the entire 110 KB from both conventional and upper memory. This is the best solution when running inside the graphical interface, since the driver is completely out of the way. The drawback is that if you shut down to "MS-DOS mode", Windows will move the driver back into conventional memory, and you will take a 110 KB hit leaving many DOS programs unable to load. The line in CONFIG.SYS if you select this option should look like: "DEVICE=C:\WINDOWS\COMMAND\DRVSPACE.SYS /MOVE". Note that if you use DEVICEHIGH, Windows will not relocate the driver to extended memory, as mentioned above.

Next: Video and Image Optimization

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