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CONFIG.SYS Commands | Device Drivers


Loads device driver you specify into the upper memory area. Loading a device driver into the upper memory area frees more bytes of conventional memory for other programs. If upper memory is not available, the DEVICEHIGH command functions just like the DEVICE command. You can use this command only in your CONFIG.SYS file. Syntax DEVICEHIGH [drive:][path]filename [dd-parameters] To specify the region(s) of memory into which to load the device driver, use the following syntax: DEVICEHIGH [[/L:region1[,minsize1][;region2[,minsize2] [/S]]= [drive:][path]filename [dd-parameters] Parameters [drive:][path]filename Specifies the location and name of the device driver you want to load into the upper memory area. dd-parameters Specifies any command-line information required by the device driver. Switches /L:region1[,minsize1][;region2[,minsize2]... Specifies one or more regions of memory into which to load the device driver. By default, MS-DOS loads the driver into the largest free upper-memory block (UMB) and makes all other UMBs available for the driver's use. You can use the /L switch to load the device driver into a specific region of memory or to specify which region(s) the driver can use. To load the driver into the largest block in a specific region of upper memory, specify the region number after the /L switch. For example, to load the driver into the largest free block in region 4, you would type /L:4. (To list the free areas of memory, type MEM /F at the command prompt.) When loaded with the /L switch, a device driver can use only the specified memory region. Some device drivers use more than one area of memory; for those drivers, you can specify more than one region. (To find out how a particular device driver uses memory, issue the MEM /M command and specify the device-driver name as an argument.) To specify two or more regions, separate the block numbers with a semicolon (;). For example, to use blocks 2 and 3, you would type /L:2;3. Normally, MS-DOS loads a driver into a UMB in the specified region only if that region contains a UMB larger than the driver's load size (usually equal to the size of the executable program file). If the driver requires more memory while running than it does when loaded, you can use the minsize parameter to ensure that the driver will not be loaded into a UMB that is too small for it. If you specify a value for minsize, MS-DOS loads the driver into that region only if it contains a UMB that is larger than both the driver's load size and the minsize value. /S Shrinks the UMB to its minimum size while the driver is loading. Using this switch makes the most efficient use of memory. This switch is normally used only by the MemMaker program, which can analyze a device driver's memory use to determine whether the /S switch can safely be used when loading that driver. This switch can be used only in conjunction with the /L switch and affects only UMBs for which a minimum size was specified. Related Commands For information about loading programs into the upper memory area, see the <LOADHIGH> command. For information about loading device drivers into conventional memory, see the <DEVICE> command. For information about using the MemMaker program to move programs to the upper memory area, see the <MEMMAKER> command.
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