UMB.DOC
Using UMB.SYS to Activate DOS Upper Memory Blocks
Microsoft with MS-DOS 5.0 and its associated HIMEM.SYS has defined a standard
mechanism for loading T&SRs and loadable drivers into the free memory
address space between 640K and 1 Megabyte. These free memory areas
are called UMBs (Upper Memory Blocks).
UMB.SYS supports the standard UMB protocol as defined in the Microsoft
XMS specification. This is useful if you are debugging a program that
uses UMBs or if you wish to use other load high utilities than the ones
supplied by Nu-Mega Technologies, Inc. (DOS 5 LH and DEVICEHIGH for example.)
To activate these UMBs with a NU-MEGA driver (S-ICE.EXE, BC.SYS or
NU-MEGA.SYS) you must use an additional driver named UMB.SYS. This
driver has no parameters and must be placed after HIMEM.SYS in your
CONFIG.SYS file. The following example using Soft-ICE as the driver
shows the order that the EMM driver, HIMEM.SYS and UMB.SYS must be placed
in your CONFIG.SYS:
DEVICE = S-ICE.EXE
DEVICE = HIMEM.SYS /M:1
DEVICE = UMB.SYS
Notes: 1. The order is critical.
2. The /M:1 parameter should be used with DOS 5.
Defining UMBs
Before using UMB.SYS you must direct the Nu-Mega EMM driver to place memory
in the holes between 640K and 1 megabyte. For S-ICE.EXE and NUMEGA.SYS you
must first run EMMSETUP.EXE (use the syntax EMMSETUP S-ICE.EXE or EMMSETUP
NUMEGA.SYS to be sure the correct memory manager is changed). For BC.SYS
you must run BCSETUP.EXE. In each case you must choose to have high memory
support and you must make sure that there are one or more H's in the memory
page map. See the manual for the specific product in question for details.
Using UMB.SYS with DOS 5
If you are using MS-DOS 5.X then UMB.SYS allows you to load device
drivers and T&SRs high using the DOS built-in commands; LH & DEVICEHIGH.
You should put the command:
dos = high;umb
as the first line in your CONFIG.SYS. See the DOS 5 documentation for details.
