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-
- EMS40.SYS
- Device Driver
-
- Douglas Boling
- 1989 No. 12 (Utilities)
-
-
- Purpose: A device driver that emulates the Lotus/Intel/Microsoft Expanded
- Memory Specification, Version 4.0, in software, permitting extended memory in
- AT-class machines to be used as expanded memory.
-
- Format: DEVICE=[d:\][path\]EMS40.SYS [nnn]
-
- Remarks: EMS40.SYS is installed by being listed in the CONFIG.SYS file.
- The drive and path information must be supplied if needed by DOS to find the
- driver at boot-up. Once installed, EMS40.SYS cannot be removed from memory
- without rebooting.
-
- The optional nnn parameter allows the user to specify the amount of
- extended memory, in KB, that will be used as expanded memory by EMS40.SYS. If
- omitted, the default value is 384 KB. By setting nnn to a smaller value than
- that of the extended memory installed, space can be reserved for extended memory
- programs such as VDISK.
-
- EMS40.SYS maps extended memory into four contiguous 16 KB pages in
- conventional DOS memory, permitting access to large spreadsheets and other data
- that would otherwise result in a "Memory Full" error. While not as fast in
- operation as a dedicated LIM/EMS board and driver, it implements, within the
- limitions of a software emulation, all 28 functions specified in LIM/EMS 4.0.
- (It does not attempt to emulate the DMA functions included in Function 28,
- Alternate Map Register Set, however.)
-
- Available for downloading from PC MagNet (see the EMS40 by Modem sidebar
- in the main article), EMS40.SYS is already compiled and ready to run. As an
- alternative, EMS40.SYS can be created from either of two program files that are
- printed in the article and are also available for downloading from PC MagNet.
- EMS40.BAS will automatically create EMS40.SYS when run once in BASIC. To create
- EMS40.SYS from the EMS40.ASM source code requires use of a macro assembler (IBM
- or Microsoft, Version 2 or later) and the following commands:
-
- MASM EMS40;
- LINK EMS40;
- EXE2BIN EMS40 EMS40.SYS;
- «MDNM»