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Appendix C: Troubleshooting 37
MCMaster User’s Guide - Rev. B06 Kingston Technology Company
If you are using a third-party memory board that allows you to configure the
board as either EMS or Extended Memory, we recommend configuring the
board as Extended memory, and using a driver like BlueMAX (from Qualitas)
or QEMM-386 (from Quarterdeck) to obtain your Expanded (EMS) memory.
Software Issues
If you're using the MCMaster to upgrade a 286-based system to a 486, you will
have more software options available to you. This chapter summarizes some of
the benefits, and some of the potential pitfalls, of upgrading.
DOS 5.0
If you installed DOS 5.0 on your system while it was still an 80286 system,
there are a few more benefits you might gain with the 80386/486 architecture.
This section mentions them briefly: for a more detailed discussion, please
consult your DOS documentation.
MS-DOS 5.0 contains a number of advanced features to take advantage of the
architecture of the 80286 and 80386 processors. HIMEM.SYS, the XMS
(Extended Memory Specification) driver, can take advantage of the 286 or 386
processor to allow DOS and other drivers to reside in the HMA (High Memory
Area), a 64K block of memory immediately above the 1 MB limit of the older
8086/88 processors.
EMM386.EXE is an Expanded and Extended Memory Manager supplied with
DOS 5.0. As you might guess from its name, EMM386 requires a 386 or 486
processor to be
useful. EMM386 provides two additional features: (1) LIM
4.0 Expanded memory support and (2) UMB's (Upper Memory Blocks).
UMB's are "spare" memory slots between the 640K DOS limit and the start of
the ROM-BIOS area. Traditionally, this area is reserved for option ROMs and
video RAM, and whatever space went unused was wasted. EMM386 and
other memory managers
such as BlueMAX and QEMM take advantage of the
486 processor's memory mapping capabilities to map memory into unused
areas, freeing up
more conventional memory (below 640K) for DOS
applications.