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IBM 7090 User Manual

IBM 7090
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7.1.
09
Index
Registers
(Systems
02.07.01.
1-02.07.15.1)
The
index
registers
are
three
identical
15-position
registers
using
shift
cells.
When
the
registers
are
read
out,
the
information
comes
out
in
complement
form
(Figure
7.1-6).
Lines
controlling
the
index
register
are:
ADD
to
XR
Gate
XRA
to
ADD
Gate
XRB
to
ADD
Gate
XRC
to
ADD
Set
XR
Hold XR
02.12.70.1
02.12.26.1
02.12.26.1
02.12.26.1
{
02.12.
72.1
and
02.12.73.1
7.1.10
Storage
Register
(Systems
02.01.
00.
1-02.
01.
37.1)
The
storage
register
is
a
36-position
register
of
shift
cells.
The
storage
register
has
eight
inputs
with
the
following
controlling
lines
(Figure
7.
1-7).
ACC
to
SR
02.12.03.1
ADD
to
SR
02.12.05.1
MQ
to
SR
02.12.08.1
OP
Keys
to
SR
02.12.09.1
SR
to
SR
02.12.10.1
IND
to
SR
02.12.13.1
Address
Switch
to
SR
03.06.12.1
SB
to
SR
02.12.50.1
Set
SRR
02.05.00.1
Hold SR
02.05.00.1
7.2.00
SERVICE
AIDS
7.2.01
One
Card
Programs
Programs
other
than
the
normal
diagnostic
programs
may
be
used
to
troubleshoot
the
machine.
For
instance,
in
diagnosing
troubles
which
appear
only
when
the
cus-
tomer's
program
is
being
run,
the
program
may
be
altered
slightly
to
isolate
the
trouble.
Then,
if
the
program
is
one
used
regularly,
it
becomes
a
good
diagnostic
in
its
altered
form.
In
cases
of
this
kind,
pass
along
the
information
to
allow
newly
released
diagnostic
programs
to
incorporate
it.
Short
programs
that
you
write
yourself
are
also
handy
when
working
on
a
machine.
Punch
these
programs
on
cards
and
save
the
time
used
to
enter
them
in
storage
with
the
keys.
Make
each
card
self-loading,
if
possible,
and
there
will
be
less
cards
to
keep
track
of. Keep a
file
of
these
one-card
programs
and add
to
it.
A few
samples
of
one-card
programs
are
given
below.
Display
Storage
This
program
causes
display
of
the
contents
of
sequential
storage
locations,
starting
with
the
location
entered
in
the
operator's
panel
keys.
The
card
is
self-loading
and
halts
on
its
first
pass
to
allow
the
operator's
panel
keys
to
be
set.
After
the
start
key
170

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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