Thanks Shahin. This conventional memory issue is just as complex as it ever was. It's an historic thing, dating from the time when the processor in the PC could only address 1Mb of memory. DOS was built to this specification and ever since we've been in pain. It was a very hot topic when everybody was trying to load DOS drivers, including network drivers, and terminate and stay resident programs, all before loading Windows 3.x. When you use Windows 95 you use virtual protected mode drivers wherever possible, which don't require conventional memory. It's best to try to run DOS programs in a Win95 DOS window to make the best of this feature.
If you must run the application exclusively in DOS mode, your PC is running DOS much as it might have in the 1980s, and you need to load the DOS drivers you require to run your devices such as sound card and CD-ROM. You use the old conventional memory tricks to squeeze more into upper memory. The basic approach is this. You create a config.sys file with lines such as:
device=himem.sys
device=emm386.exe noems
dos=high,umb
devicehigh=
On each line that starts with devicehigh you put the device drivers you need, such as CD-ROM drivers.
Then in the autoexec.bat file you place the other lines you need, including the Microsoft CD extensions line. Use the loadhigh (lh) command to load these into upper memory where possible, eg:
lh MSCDEX.EXE /E:MSCD_000 /M:16 /V
If you don't know what these lines should be, try this. Make a note of the settings of your sound card and CD-ROM drive. You can do this in Win95 by opening the System module in Control Panel, clicking the Device Manager tab and double-clicking on the CD-ROM and sound card devices. Note the interrupts and base address settings. I'm assuming these work. Copy the existing autoexec.bat and config.sys files to a safe place.
Now restart your computer in MS-DOS mode. Find your CD-ROM and sound card installation disks and run them. They'll probably add the appropriate lines to your configuration files. There'll probably be a configuration program which sets the IRQ and base address for your devices, and you'll probably find they're set to the values you've already noted down. If not, set them to those values.
When you have a configuration that correctly runs your devices in DOS mode, copy the new autoexec.bat and config.sys files to a safe place for later reference.
For each DOS mode application you can create specific autoexec.bat and config.sys files before loading the application. When you've finished using the application, you type Exit to return to Windows 95. This is really just a system for managing multiple DOS configurations, but it's convenient.
Now, right-click on the program or a shortcut to it and click Properties. Now in the Properties menu, click the Program tab, and click the Advanced button.
You'll notice that the Advanced Settings dialogue box referes to a .pif file, like the old Win3.x pif files. However, this one lets you check an MS-DOS mode box. When you do, you can choose to use the existing configuration or a new one. There are text boxes where you can type in the config.sys and autoexec.bat configurations specific to this application.
When you've finished, you just click on the shortcut to run the application. Win95 warns you that you're entering DOS mode, closes all your applications and runs MS-DOS with the settings you specify.
- Neale Morison