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IBM 7090 User Manual

IBM 7090
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card
enter
storage
location
zero,
one,
and
two.
The
word
entered
in
address
zero
should
be
a
control
word.
When
the
word
counter
goes
to
zero,
the
channel
asks
for
another
control
word
from
location
zero.
The
CPU
gets
its
next
instruction
from
loca-
tion
one.
Load
Tape
Key
(Figure
6.1-13)
The
load
tape
key
works
the
same
as
the
load
cards
key,
causing
a
reset
to
the
CPU
and
all
channels
not
in
manual
status.
The
load
tape
key
also
causes
a
read
select
of
tape
unit
1 on
channel
A,
IOCP
word
count
of
3.
The
next
command
for
the
channel
will
come
from
location
zero,
and
the
next
instruction
for
CPU
will
come
from
location
00001.
Sense
Control
There
are
two
types
of
sense
controls
on
the
operator's
panel:
sense
lights
and
sense
switches.
The
conditions
of
these
sense
devices
may
be
checked
by
machine
instructions
and
used
to
control
program
flow.
The
four
sense
lamps
on
the
panel
may
be
turned
on
or
off
by
instructions
in
the
main
program
and
then
checked
by
the
sense
instructions.
The
condition
of
the
lamp
determines
if
the
program
steps
are
to
be
skipped.
The
six
sense
switches
may
be
set
on
or
off
from
the
operator's
panel.
The
condition
of
the
switch
may
then
be
checked
by
sense
instructions
in
the
program
to
determine
whether
to
skip
the
following
program
step.
6.2.00
CUSTOMER
ENGINEER'S
TEST
PANEL
In
addition
to
the
indicators
and
manual
controls
on
the
operator's
panel,
the
customer
engineer
has
at
his
disposal
the
indicators
and
controls
on
the
customer
engineer's
test
panel.
The
indicators
provide
a
means
for
checking
the
address
register
contents,
the
tally
counter,
various
test
triggers,
and
the
cycle
time.
The
switches
and
jacks
provide
means
to
continually
execute
any
instruction,
control
1-0
operation,
control
B
time,
and
step
through
instructions
cycle
by
cycle.
Figure
6.2-1
shows
the
layout
of
indicators
and
controls
for
this
panel
and
designates
system
page
locations.
6.2.01
Indicators
Indicators
on
the
customer
engineer's
test
panel
are
of
the
incandescent
type.
Indicators
connected
to
test
triggers
are
on
when
the
trigger
is
on and off when
the
trigger
is
off.
Indicators
concerned
with
the
registers
and
counters
signify
a 1
when
they
are
on
and
a 0
when
off.
Address
Register
The
address
register
contains
the
address
portion
of
the
instruction
under
execution.
158

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IBM 7090 Specifications

General IconGeneral
CategoryMainframe Computer
Introduced1959
Transistor-basedYes
Word Length36 bits
Add Time4.8 microseconds
MemoryCore memory
Memory (words)32, 768 words