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PROGRAMMED
I/O
BUS SIGNALS
Data Bus
(KDBOl-
through
KDB12-
)
Signals
KDBOl-
through
KDB12-
from
the
controller
represent
the
contents
of
the
ac-
cumulator
(A-register) during
OOP, SMK,
and
OTA
commands.
During
INA
commands
the
addressed
peripheral device places data on
this
bus
for
eventual gating
into the
accumulator.
The
interface
must
leave these
lines
at
+6
volts
until
a
data transfer
to
the controller
is
nnade
in
response
to
an INA.
Thus
these signals are
bidirectional,
being outputs during
OTA's,
SMK's
and
OOP's
and
inputs
during
INA commands.
A
line
will
be
at
ground
when
the
cor-
respondingly
numbered
bit in
the
accumulator
is
set
and
+6V when
reset.
To
transfer
a
ONE
into the
accumulator
in
particular
bit
position
during an
INA command,
the
corresponding
line
must
be grounded.
Address Bus
Lines
(KABOl-
through
KAB06-)
The
six output signals
KABOl-
through
KAB06-
are
the least significant bits
of
the
W-
register
and carry
the
address
portion
of
the
I/O
instruction.
KABOl-
corresponds
to
instruc-
tion
bit
1
and
KAB06-
to bit
6.
Instruction
Lines
(KOTAL-, KINAL-.
KOCPL-, KSKSL-
)
An
output
on one
of
the lines
KOTAL-,
KINAL-,
KOCPL-, KSKSL-
indicates
that the
execution
of
an
OTA,
INA,
OOP,
or
SKS, respectively
is
in
progress.
Execution
of
an
SMK
causes
the
OCP
line
(KOCPL-)
to
pulse.
Set
Mask (KSMKL-
)
The
output signal
KSMKL-
will
be
at
ground
during
the
execution
of
either
an
SMKO
or
SMKl
instruction.
The
peripheral device
is
to
use
this line
with
KAB01+
or
KABOl-
to
deter-
mine which
instruction
is
being executed
and
the
appropriate data bus
bit to
set
or
reset
the
mask
flip-flop.
(KABOl-
is
used
for
SMKO
and
KAB01+
is
used
for
SMKl).
Strobe
Signal
(KSTRB-
)
The
output signal
KSTRB-
indicates
that
an
active (ground) test signal
has been recognized
during
either
an INA,
OTA,
or
SKS
instruction, that the
next instruction
will
be skipped, and
that a
data transfer,
if
any, will
take place.
During
OCP
and
OTA
commands,
this
signal also
serves
to
define the
time
when
the
address and
data
lines
are
stable.
During
OTA,
INA, and
in
some
cases during
SKS commands,
STROBE
is
used
to
reset
a
ready
flip-flop.
This
signal
is
also
active,
but
redundant during
execution
of
an
SMK.
Interrupt Signal
(KINTL-
)
KINTL-
is
an
input signal
to
the controller.
This
line
is
made
active (ground)
to
inter-
rupt
the
program,
and held
until
the
interrupt
is
recognized.
The
line
is
made
+6
volts
when
the
controller resets
the
interrupt via
separate
programming
action.
This
is
usually
accom-
plished via data transfer or
OCP
instruction.
2-3
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