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Memory Map Showing Upper, High and Extended Memory
Displaying the Current Memory Configuration
Before you begin making changes to optimize the way in which your system uses memory, it is important that you know what types of memory are available on your computer and how memory is currently being used.The MEM command displays extensive information about memory usage. Refer to the ``Command Reference'' chapter of DOSBook for a detailed description of the MEM command. For a brief description of MEM and its options, simply enter either of the following version of the MEM command at the system prompt:
MEM /?
MEM /H
DR-DOS Memory Managers
To access extended, expanded, or upper memory, the operating system includes memory managers. A memory manager is a special device driver that provides access to different memory types. The memory manager you use depends on what type of hardware you are using.
EMM386
The EMM386 memory manager provides access to the upper memory area. It also uses extended memory to emulate expanded (EMS) memory for those applications that need it.Use EMM386 if your computer is a 386-based machine or later.
EMM386 is loaded and configured by a DEVICE statement in the CONFIG.SYS file. This statement is automatically placed in CONFIG.SYS when you choose to load the 386 memory manager during SETUP (or INSTALL). The configuration of EMM386 depends on the values you set in SETUP and on changes you make yourself to CONFIG.SYS.
The full syntax of the EMM386 DEVICE statement is as follows:
DEVICE = C:\DRDOS\EMM386.EXE [[/]?|[/]H] [[/]AUTO]
[[/]COMPAQ[=ON|OFF]] [[/]DPMI[=ON|OFF]]
[[/]EXCLUDE=start-end[,start-end]...]
[[/]FRAME=AUTO|NONE|address] [[/]GATEA20=type]
[[/]INCLUDE=start-end[,start-end]...]
[[/]INT15=kb] [[/]MULTI[=ON|OFF]] [[/]OFF] [[/]ON]
[[/]ROM=start-end[,start-end]...]
[[/]USE=start-end[,start-end]...]
[[/]VIDEO[=[start-]end]] [[/]VXD=path]
[[/]WEITEK=ON|OFF] [[/]WINSTD] [[/]XBDA] [[/]XMSUMB]
The following table describes the EMM386 options. For information about specifying these options, either through SETUP or by editing CONFIG.SYS yourself, see ``Making More Memory Available'' on page 10-10.