PLUS Series Technical Notes
#52: Memory management utilities and Plus Series programs

Memory management utilities can improve performance and usefulness of suitably equipped computers. This document contains a highly technical discussion of some issues involved when running CD-ROM programs (such as Bowker's Plus Series, and the Martindale-Hubbell Law Directory on CD-ROM) under various memory managers.

UMB memory can be implemented on 386-based computers by using the EMM386.EXE driver which accompanies DOS v5.0 and v6.0. Third party memory managers such as Quarterdeck's QEMM and Qualitas' 386MAX also implement UMB memory in their recent releases. Similar products are available for suitably equiped 286-based computers.

Customers may attempt to load the Microsoft CD-ROM Extensions into upper memory blocks explicitly (by invoking the DOS LOADHIGH command). Third-party memory managers provide installation programs that will set up the customer's computer to place MSCDEX into UMB memory. For example, QEMM's Optimize program will change AUTOEXEC.BAT to load MSCDEX into UMB memory using Quarterdeck's LOADHI.EXE program. This document will focus on QEMM, since it is the most popular third-party memory manager.

Several customers have reported that the CD-ROM Extensions will give unpredictable results if MSCDEX is loaded into UMB Memory. Others have reported no difficulties. In limited testing, we have discovered that using Quarterdeck's LOADHI.EXE rather than the DOS LOADHIGH command gives better results. The success or failure of loading MSCDEX high appears to involve several factors; BIOS manufacturer and date, motherboard manufacturer, etc. No clear rule applies; for maximum compatibility, we recommend that customers do not load MSCDEX high, if they are using a version of MSCDEX prior to 2.21

Current device drivers (HITACHIA.SYS, SONY_CDU.SYS, etc.) can be loaded into UMB memory without problems.

Placing MSCDEX into upper memory should have no impact on the Bowker Plus Series products, since none of them use MSCDEX.

The MARTINDALE-HUBBELL Law Directory on CD-ROM does use MSCDEX, and thus will be affected.

If the customer is experiencing problems with other CD-ROM products, and wish to avoid this, try loading MSCDEX as a conventional TSR. This means either adding MSCDEX to the list of programs that Optimize will ignore (see the QEMM documentation for this procedure) or changing AUTOEXEC.BAT after Optimize has been run. Change the line that reads

	C:\QEMM\LOADHI C:\BIN\MSCDEX . . .

to read:

	C:\BIN\MSCDEX . . .

Since QEMM provides EMS memory, the conventional memory required to run MSCDEX can be reduced by adding the /E parameter. This will force MSCDEX to allocate its buffers in EMS memory, and should keep the conventional memory usage down to about 15K. This may or may not work with other memory managers, depending on how they are configured.

In summary:

• If using EMM386.EXE, do not load MSCEX high.
• If using QEMM, load MSCDEX high using LOADHI.EXE rather than LOADHIGH.
• If problems occur with CD-ROM products under QEMM, do not use LOADHIGH.
• In all cases, use the /E parameter to free up conventional memory.