FreeDOS help system (hhstndrd 1.0.8 en)[xmgr]

Command: xmgr.sys

XMGR.SYS is a DOS driver that works as an XMS memory manager. XMGR.SYS has to be loaded in CONFIG.SYS / FDCONFIG.SYS.


DEVICE [HIGH] = [path] XMGR.SYS [/B] [/Mn] [/Nnn] [/PA] [/Tn] [/W] [/Z]


XMGR.SYS usually needs only its /B switch if "booting" with JEMM386. XMGR.SYS switch options are as follows: /B Specifies "boot" mode. XMGR.SYS loads in temporary memory until upper-memory is enabled by EMM386. Without /B, XMGR.SYS will load stand-alone in low memory or directly in upper-memory with UMBPCI. /Mn Specifies the temporary area used to load XMGR.SYS in "boot" mode and used for UMBPCI upper memory I/O before DOS can post a "workspace" buffer. Values are: /M1 = 64K. /M3 = 192K. /M5 = 320K. /M7 = 448K. /M2 = 128K. /M4 = 256K. /M6 = 384K. /M8 = 512K. Without /M, /M5 is assumed and the 320K area will be used. NOTE: A DOS system often may NOT load at address 0 up and may leave temporary data anywhere in memory! /Mn changes the temporary area to find a "safe" place for XMGR.SYS to use. /M is ignored if XMGR.SYS loads stand-alone. /Nnn Specifies how many XMS "Handles" can be used by DOS programs. The value nn may be 48, 80, or 128. If /N is omitted, 48 "Handles" are used and work fine for most systems. A big system doing much XMS work may need 80 or 128 "Handles". /PA Specifies use or non-use of PS/2 Port 92h logic to handle the /PN system's "A20" line. /PA indicates "Always" use Port 92h logic. /PN indicates "Never" use it and handle "A20" via normal keyboard-port logic. If /P is omitted, XMGR "asks the BIOS" if the system has Port 92h logic. If not, XMGR will use normal "A20" logic. NOTE: If "A20" was enabled by DOS before XMGR loads, XMGR does not handle it at all! /Tn Specifies the BIOS requests to use in getting extended memory as follows: /T0 Neither "E820h" nor "E801h" requests. /T1 Memory-list requests only (Int 15h, AX=E820h). /T2 A dual-area request only (Int 15h, AX=E801h). /T3 "E820h" requests first, then an "E801h" request. /T can usually be omitted, which causes /T3 to be assumed. In addition, XMGR.SYS always uses an old 64-MB request, to get extended memory for /T0, or if the requests specified with /T1 through /T3 are unsuccessful. Users may need to test /T1 and /T2 separately, to see if their BIOS accepts them. A pre-1994 BIOS may not "ignore" /T1 through /T3 properly and may require /T0 to be used. For compatibility with older QHIMEM drivers, /T4 through /T7 may be used and work the same as /T0 through /T3. /W Specifies use of the DOS "workspace" buffer, for upper-memory I/O if loading with UMBPCI. If /W is omitted, or if the DOS system does not have proper workspace logic, XMGR.SYS will set its own buffer in low memory. An EDR-DOS system must OMIT this switch! Without UMBPCI, /W will be ignored. /Z For XMGR or UIDE only, limits their XMS moves to a maximum 2K bytes in protected-mode, not 64K. /Z is ignored by real-mode systems (UMBPCI etc.) and is not needed if JEMM386 or EMM386 handle protected-mode. Systems using other VCPI/DPMI/EMM drivers must be TESTED, to see if /Z is needed by XMGR or UIDE -- BAD schemes allowing NOT enough interrupts in an XMS move may still exist! UIDE's old /N4 switch is the same as /Z and can still be given. UIDEJR ignores /Z or /N4 and always issues standard XMS calls. For each switch, a dash may replace the slash, and lower-case letters may be used.


XMGR.SYS is a DOS driver that works as an XMS memory manager. It supports V3.70+ UMBPCI by Uwe Sieber. After UMBPCI enables upper- memory, XMGR.SYS can load there directly and provide both upper and XMS memory for a DOS system. XMGR.SYS uses an "I/O catcher" with UMBPCI, to intercept diskette or hard disk I/O above 640K. Such I/O is done through a low memory area, to avoid DMA trouble in UMBPCI "Shadow RAM". XMGR.SYS also supports V4.49 and V4.95 EMM386 (MS-DOS V6.22 or V7.10). With JEMM386, XMGR.SYS using its /B switch can first "boot" into temporary space. After JEMM386 enables upper-memory, XMGR.SYS loads there with no /B switch, copies all its "boot" data, and takes-over XMS work. Only its XMS "Handles" table stays in low memory, so EMM386 can always find them at fixed addresses. For a small XMS-only system, XMGR.SYS can also load entirely in low memory. For more information read "README.txt" in



See also:

(atapicdd.sys) autoexec.bat config.sys devload (emm386) fdconfig.sys (fdxms) (fdxms286) (gcdrom.sys) (himem) himemx jemm386 jemmex (mscdex) shsucdx (udvd.sys) uide.sys (xcdrom.sys) ------------------------------------------------------------------------------ Copyright (C) 2007 Jack Ellis, updated 2011 by W. Spiegl. This file is derived from the FreeDOS Spec Command HOWTO. See the file H2Cpying for copying conditions.