Quarterdeck Tools for Memory Management

Published ByDateVersionKnowledge LevelKeywords
Revelation Technologies11 APR 19891.1XNOVICELOADHI.COM, MEMORY, NOEGA.COM, QEMM, RAM

Quarterdeck Office Systems, the developer of Desqview, has available an extended memory manager for 80386 machines that has the ability to increase the amount of string space for Advanced Revelation. This bulletin describes some of the potential benefits for Advanced Revelation users.

QEMM.SYS is a device driver, loaded by the CONFIG.SYS file, which is primarily designed to simulate expanded memory from extended memory. This feature by itself may be useful to some; however, the driver has some ancillary capabilities which can be used to advantage by Advanced Revelation users.

QEMM has the ability to backfill unused memory in the range between 640K and 1MB. If this feature is enabled, it will look for video and ROM in this range, and then fill any unused portions with RAM. This memory can then be used by a supplied utility called LOADHI.COM for transparently loading device drivers or TSR programs. For Advanced Revelation users, network shells are an obvious candidate for this facility.

In addition, if QEMM finds unused video memory in the range between 640K and 736K, it will fill this memory with RAM. Most versions of DOS will locate this memory and report it to programs (such as Advanced Revelation Version 1.1) which ask DOS for the upper limit of RAM. Thus Advanced Revelation 1.1 in conjunction with QEMM.SYS will use this memory for additional string space.

Another utility can be used by those who have an EGA adapter (which has memory between 640K and 704K) but who would rather have extra memory for Advanced Revelation than use the EGA modes of their video adapter. This is logical, since Advanced Revelation won't use these modes even if they are available.

Unused EGA can be used by Advanced Revelation by forcing QEMM to fill it (using a command line parameter). Then by running the supplied utility NOEGA.COM, no program will be able to detect the presence of an EGA adapter. Thus even users with EGA adapters can raise the DOS memory limit from 640K to 704K. Since NOEGA.COM is a TSR program, it can itself be loaded using LOADHI.

To give an idea of the kinds of savings possible, here is a chart showing the initial amount of string space under Advanced Revelation 1.13 on a Compaq 386 with extended memory:

ConditionInitial String Space
Space - No QEMM, no net shell299K
No QEMM, with net shell271K
QEMM, net shell loaded with LOADHI319K
As above with 640K-704K filled378K

Desqview is a trademark of Quarterdeck Office Systems.

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