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Q64591: EMS40.SYS Is Valid LIM 4.0 Driver for EM Use in BASIC PDS

Article: Q64591
Product(s): See article
Version(s): 7.00 7.10
Operating System(s): MS-DOS
Keyword(s): ENDUSER | SR# S900717-157 EMS40 | mspl13_basic
Last Modified: 5-SEP-1990

EMS40.SYS is a device driver that emulates the Lotus/Intel/Microsoft
(LIM) Expanded Memory Specification (EMS) version 4.0. This software
permits AT-class machines with extended memory to adapt their extended
memory (defined by XMS) to expanded memory (defined by EMS). This
driver is compatible with Microsoft BASIC Professional Development
System (PDS) versions 7.00 and 7.10 and can map BASIC PDS source code
segments less than 16K in size to the expanded memory of the machine.

EMS40.SYS is freeware and it is available for downloading from the PC
MagNet bulletin board. Although the source code is also available on
MagNet, EMS40.SYS is already compiled and ready to use. Much of the
information in this article comes from the "readme" file also
available on MagNet.

EMS40.SYS can be installed as a driver specified in your CONFIG.SYS
file with the syntax shown below. The drive and path should be
specified so the system can find the driver during machine boot-up.
Once installed, EMS40.SYS cannot be removed from memory without
rebooting the computer.

   DEVICE=[LogicalDriveName:\][path\]EMS40.SYS [xxx]

The optional "xxx" parameter allows you to specify the amount of
extended memory in kilobytes (K) to be used as expanded memory by
EMS40.SYS. If the "xxx" parameter is omitted, the default value is
384K. By setting "xxx: to a smaller value than that of the extended
memory installed, space can be reserved for extended memory programs,
such as HIMEM.SYS.

EMS40.SYS maps extended memory into four contiguous 16K pages in
conventional DOS memory and permits access to memory in situations
that otherwise could result in a "Memory Full" error. EMS40.SYS is not
as fast as a dedicated LIM 4.0 EMS board and driver, but it implements
(within the limitations of software emulation) all 28 functions
specified in the LIM 4.0 EMS. It does not attempt, however, to emulate
the DMA functions included in Function 28, Alternate Map Register Set.

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