EMS

The following settings control the behavior of EMS memory used by the VDM.

EMS_FRAME_LOCATION

Function:

This DOS setting allows you to change the location of the LIM EMS region. LIM EMS uses a 64KB address region known as an EMS page frame, through which programs can access expanded memory. (This allows programs to use more than 640KB of memory.)

If a user has problems when running a program that uses both a hardware device and LIM EMS expanded memory, the problem may be due to conflicting use of addresses by LIM EMS and the hardware device. If this occurs, the user should first use the EMS_HIGH_OS_MAP_REGION setting to set the extra address region used by EMS to 0. This may solve the problem. If the problem persists, the EMS_FRAME_LOCATION setting can be used to select a 64KB region that does not conflict with hardware.

The user can choose where to place the frame from a list of choices or can choose to have no EMS frame for programs which do not require a frame. The user can also reduce the DOS Memory Size setting and place the frame below 640KB.

The best solution, when problems due to hardware conflicts occur, is to use the MEM_EXCLUDE_REGIONS and MEM_INCLUDE_REGIONS settings to specify the addresses that the hardware uses rather than using this setting.

The default AUTO setting will lead to correct choices of LIM EMS addresses. Most users will never need to change this setting.

At VDM creation time only.

In some cases the default choice may conflict with addresses used by hardware on the machine. This can happen only for devices that are not supported by a virtual device driver.

EMS_HIGH_OS_MAP_REGION

Function:

In addition to the EMS page frame, some programs can use additional addresses to access expanded memory. This setting gives advanced users the capability to adjust the size of the additional EMS region.

See also EMS_FRAME_LOCATION above.

An advanced user can use the MEM_EXCLUDE_REGIONS and MEM_INCLUDE_REGIONS settings to specify the addresses used by devices that do not have virtual device drivers, and can then set the size of the EMS_HIGH_OS_MAP_REGION appropriately for their program. This helps avoiding conflicts with addresses used by devices and programs.

The value set is the size of the region in kilobytes. The default is 32KB.

At VDM creation only.

None.

EMS_LOW_OS_MAP_REGION

Function:

Some programs can use remappable conventional memory. Others do not use this feature. This setting allows advanced users to set the size of the remappable conventional memory available in a VDM.

The value set is the size of the region in kilobytes. The default is 384KB.

At VDM creation only.

None.

EMS_MEMORY_LIMIT

Function:

This setting controls the amount of EMS memory available to a VDM.

The user can set this to a higher value for running programs that require a large amount of EMS memory. Other programs do not use EMS at all. The size can be set to 0 in such cases, to disable EMS support for that VDM. Programs generally state whether they use EMS on the box or in their manuals.

The value set is the size of the region in kilobytes. The default size is 2MB.

At VDM creation time only.

If a spreadsheet runs out of memory, the amount of EMS memory can be increased and the VDM restarted.