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Q97872: EMS Not Recommended with LAN Man, Windows 386 Enhanced

Article: Q97872
Product(s): Microsoft LAN Manager
Version(s): 
Operating System(s): 
Keyword(s): 
Last Modified: 30-JUL-2001

SUMMARY
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Expanded memory emulators use processes that, under some circumstances, can
retard or stop system operation.

MORE INFORMATION
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Expanded memory managers differ from expanded memory hardware. Software
emulators each behave with some unique characteristics and may even behave
differently from version to version. An emulator that breaks in one environment
may work fine in another.

EMM386 is an emulator type, which depends on protected mode mechanisms. The
emulation is much slower than hardware and during the switch locks out
interrupts.

If expanded memory is used too frequently, the system spends too large a portion
of its bandwidth just switching, and this increases the periods during which
interrupts are not serviced. Users sometimes hang when interrupts are missed,
due to driver situations.

One of the most common problems with expanded memory emulators, is dropped
characters in serial communications applications at high data rates, although
some applications might be able to hide such troubles under certain conditions.
Another problem is hanging up an environmental shell, such as Windows.

Recent versions of the NETWORK.WRI file for Windows 3.1 state that if you are
running Windows in 386 enhanced mode, using expanded memory with LAN Manager is
not recommended because it may downgrade system activity. (One version said
downgrade or HALT; this difference is due to the unpredictability of system
performance factors when expanded memory is involved.)

Additional query words: 2.00 2.10 2.10a 2.20

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