On some 80386 machines, the upper memory area (UMA) can become fragmented
by the presence of ROM BIOS extensions, video RAM, and so forth. If
EMM386.EXE cannot find 64K of available contiguous RAM in the UMA, it
cannot establish a page frame. In such cases, the Pn= option can be used to
allocate a partial and/or noncontiguous page frame in 16K segments.
For example, EMM386.EXE can be used to install a noncontiguous, 64K page
frame with four 16K segments at C800, CC00, D800, and DC00 by using the
following command in the CONFIG.SYS file:
device=c:\dos\emm386.exe P0=C800 P1=CC00 P2=D800 P3=DC00 RAM
Alternatively, a 16K segment, or partial page frame, can be installed at
DC00 using the following command in the CONFIG.SYS file:
device=c:\dos\emm386.exe P0=DC00 RAM
Note that both of the above examples provide expanded memory in accordance
with the LIM 4.0 EMS. Applications requiring LIM 3.2 EMS may not be able to
recognize or use this EMS.