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Installation
and
Specifications
MEMORY
MAPPING
Memory
Address
The
7706
has
four
memory mapping
options.
Figure 2-7
shows
the four
options,
the
address
thai
each
memory
part
occupies,
and
how
jumper
W4
should
be
configured
fo
select
each
option.
Each
option
maps
the
card
to
a
different
16K
quadrant
of
a
64K memory
system.
The
card
comes
from
fhe
factory
mapped
to
the
last
quadrant, address
C000.
The
four
optional starting
addresses
are:
COCO
4000
8000
C000
The
other versions
of
the
7706
have
fewer
memory
parts
installed.
The
memory
parts
used
are:
2K
version
has
RAM
0
4K
version
has
RAMs
0 and
I
8K
version
has-
RAMs
0,
1,
2,
and
3
Like the
16K
version,
these versions
have
only the four
mapping
options already
mentioned.
Therefore,
an
8K
card
can be
mapped,
for
instance,
a:
C000-DFFF,
but
not
F000-
FFFF.
If
an
8K
card
mapped
at
E000-FFFF
is
needed,
it
is
pos-
sible
to
configure
one by
using a
16K
card
and
disabling the
lower 8K.
Using
this
method,
any amount
of
RAM
can be
located
at
any
part
of
the
16K
quadrant
in
which
the
7706
is
mapped.
Note
that
a
card cannot
be
mapped
to
straddle
a
16K
boundary, such
as
B000-CFFF.
Caution
Users should
not
install
additional
memory
parts
in
boards
that are
only
partially
populated.
The
memory
parts
Pro-Log uses
are selected
for
low
power consumption and
severely
tested,
guaran-
teeing
at least
two years data
retention.
Other
sources
of
functionally
compatible
CMOS
RAMs
have been found
to
draw up
to
100
times as
much
current.
Such
current drains
would
shorten
battery
life
severely,
making
it
impossible
to
determine
when
the battery
will
fail.
If
memory
parts
are
added by
the
customer, Pro-Log
will
consider
the
warranty
on
battery
life
to
be
void.
mi
Figure
2-8.
7706
Chip
Disable
Jumpers
2-7
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