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IBM 7090 - Operators Panel; Indicators

IBM 7090
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6.1.
00
OPERATOR'S
PANEL
The
operator's
panel
provides
for
visual
checking
of
the
information
in
the
computer
and
for
manual
control
of
the
computer's
functions.
It
is
also
a
station
from
which
power
may
be
applied
to
or
removed
from
the
system.
6.1.01
Indicators
All
indicators
on
the
console
are
of
the
incandescent
type.
When
used
to
indicate
the
condition
of a
register,
a
lamp
being
on
signifies
a
1,
while
a
lamp
being
off
Signifies
a
O.
Internal
Registers
The
contents
of
the
internal
registers
(accumulator
t
multiplexor-quotient,
storage
register,
instruction
counter,
instruction
register,
and
index
registers
A,
B,
and
C)
are
displayed
directly
on
the
panel.
Trap
This
lamp
is
on
whenever
the
machine
is
in
the
transfer
trapping
mode.
Simulate
The
simulate
lamp
is
on when
the
7090
is
operating
in
any
of
the
following
modes
associated
with
the
704, 709,
or
7090
compatibility
program:
1.
1-0
select
and
sense
trap
mode
2. Copy
and
locate
drum
address
trap
mode
3.
Storage
nullification
mode
Accumulator
Overflow
The
a
ccumulator
overflow
lamp
is
on
any
time
during
a
fixed
point
operation
(add,
subtract,
and
so
on)
or
shifting
operation
that
a
carry
out
of
position
1 of
the
accumu-
lator
occurs.
It
is
also
turned
on
by
a
bit
in
position
P
during
the
execution
of a
float-
ing
point
instruction
while
in
compatibility
mode.
It
may
be
turned
off
by
the
TNO
or
TOV
instruction.
Quotient
Overflow
This
lamp
is
on
whenever
the
computer
is
using
the
compatibility
program
and
an
MQ
overflow
occurs.
Read-Write
Select
The
read-write
(R-W)
select
lamp
is
on
whenever
the
channel-in-use
trigger
is
on
in
any
data
channel.
146

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