Owner`s manual
A3.4 Mapping Registers
Every
page
of
EMS
memory
is 16KB in size. By setting
the
mapping
registers
to
values
from
0 to
127,
one
of
the
16KB
pages in a two-megabyte
EMS
memory
board
can
be
mapped
into
the
page
frame
window.
With
bit
0 to
bit
6 ac-
counting
for
the
0
to
127
range,
the
last
bit
(MSB)
in
the
mapping
register
can
be used as
an
enable/disable flag
for
that
particular
page.
Each
mapping register
can
handle
up
to 2 megabytes
of
EMS
memory (16KB x
128
= 2M). Since
each
page
frame
is 64K,
four
such pages
can
be
mapped
into
the
window
at
any
time.
These
four
mapping
registers
are
located in
the
following addresses:
02X8
42X8
82X8
C2X8
X is
the
variable selected by dipswitch SW1
and
SW2 (EMS
I/O
port
address select).
In
theory,
SW1
and
SW2
can
select
X
from
0
to
F;
but
in
order
to
avoid conflicts
with
other
I/O
devices,
the
Everex
EMM.SYS device
driver
will
accept
only
these X values:
0,
1,
5,
6,
A,
B,
E
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