JUMPERS
There are six jumpers on the
board
to
allow
configuring
your
CPU
for
special
situations.
The
chart
below
shows
their
"normar
positions.
NAME
NO~MAL
POSITION
~EMA~KS
STV (Status
Valid)
"0" Used
with
OMA
STK
"E"
Used
with
DMA
1-0
"8" Puts
lower
8-bit
1-0
address on
upper
8-bits
PHANTOM*
"+"
Connects
PHANTOM* line
SXI<Q
(sXTRQ*)
"+"
Connects Sixteen Request line
MWRITE
"+"
Connects
MWRITE
line
Each
of
these jumpers
will
be discussed in
more
detail
to
enable
you
to
determine
if
you
should change them
to
the alternate
position.
STV (Status
Valid)
--
this jumper
controls
the
function
of
the pSTVAL* line (S-100
pin
25)
during
OMA:
In
the
"E"
position
the CPU always drives the pSTVAL*line.
In
the
"Ui
position
this line
is
three-stated
when
COSH*
(control
disable, S-100
pin
19)
is
low
allowing
the OMA
device
to
drive
it.
'-
STK
--
this jumper
controls
the
function
of
the
"SPEED"
line (S-100 pin
98)
during OMA.
In
the
"E"
position
the CPU always drives this line
with
ahigh
to
indicate
8MHz
operation
or
low
to
indicate
4M
Hz
operation.
In
the
"D"
position,
this line
is
three-stated
when
SDSl:3·
(status disable,
5-100
pin
18)
is
low
allowing
the
UMA
device
to
drive
it.
1-0
--
In
the
normal
"8"
position,
this jumper copies the
lower
8bits
of
I-Q
address
information
onto
the
next
higher
8address bits. If
your
1-0
devices
use
a
16-bit
address, the
jumper should
be
in the
16-bit
position.
Most
existing
I-Q
devices use addressing in
which
the
lower
and middle address bytes are the same.
The
upper address byte,
A16-A23,
is
never used in
I/O
addressing.
PHANTOM*
--
This
CPU
board
generates aPHANTOM* signal whenever
it
addresses
memory
locations
located
above
the
lowest
64K. This signal may be used
to
disable
older,
8-bit
memory
cards
which
do
not
have extended addressing. Through the
use
of
this PHANTOM· signal, asystem
may be
composed
of
up
to
64K
of
the
older,
non-extended
addressable
memory
which
would
be
located
in the
lowest
64K and
newer,
extended addressable
memory,
located
in the higher
addresses. The PHANTOM* signal
would
prevent
the
older
memory
from
interfering
with
the
memory
located
at
the higher addresses. If
your
system
uses
this signal
for
some
other
purpose,
the
PHANTOM* generated
on
the CPU
board
should be disconnected
from
the
bus
by
putting
the
PHANTOM* jumper in the "_"
position.
sXT~Q*
--
The Sixteen Request signal
is
generated by the
CPU
whenever
it
wants
to
do
a
16-bit
transfer.
In
our
system, using
16-bit
memory,
this jumper should be
connected
in the
"+"
postion.
If
you
do
not
have
16-bit
memory
in
your
system, the signal
would
serve
no
purpose and
the jumper
could
be
in
either
position.
If
your
system
uses
bus
line 58
for
some
other
purpose, the
sXT~Q*
line should be
disconnected
between the
CPU
and the
bus
by placing the jumper in the "_"
position.
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