EasyManuals Logo

IBM 7090 User Manual

IBM 7090
190 pages
To Next Page IconTo Next Page
To Next Page IconTo Next Page
To Previous Page IconTo Previous Page
To Previous Page IconTo Previous Page
Page #127 background imageLoading...
Page #127 background image
Place
Index
in
Decrement
PXD
-0754
(I)
Figure
5.3-63
This
instruction
places
the
true
contents
of
the
specified
index
register
in
positions
(3-17) of
the
AC.
The
remainder
of
the
AC
is
cleared.
Execution
of
this
instruction
is
similar
to
PXA.
However,
because
no
shift
is
required,
the
index
register
contents
can
be
routed
directly
from
the
adders
to
the
AC.
Store
Index
in
Address
SXA +0634 (I, E)
Figure
5.3-64
This
instruction
stores
the
true
contents
of
the
specified
index
register
in
the
address
field
(21-35) of
storage
location
X.
The
remaining
positions
of
location
X
are
unchanged.
The
logic
of
the
execution
of
this
instruction
is
similar
to
PXA.
However,
an
E
cycle
is
needed
to
put
the
information
in
core
storage.
Store
Index
in
Decrement
SXD
-0634
(I, E)
Figure
5.3-64
This
instruction
stores
the
true
contents
of
the
specified
index
register
in
the
decrement
(3-17) of
storage
location
X.
The
remaining
positions
of
location
X
are
unchanged.
Execution
of
this
instruction
is
similar
to
SXA
but,
because
there
is
no
shift
required,
the
output
of
the
adders
goes
directly
to
the
SR.
Address
to
Index
True
AXT +0774
(I)
Figure
5.3-65
This
instruction
loads
the
specified
index
register
with
the
address
field
(21-35)
in
true
form.
Address
to
Index
Complemented
AXC
-0774
(I)
Figure
5.3-65
This
instruction
loads
the
specified
index
register
with
the
2's
complement
of
the
address
portion
(21-35) of
the
instruction.
Execution
ofAXC
is
similar
to
that
of
AXT
except
that
the
index
register
contents
must
be
cycled
through
the
adders
during
the
following
I
cycle
to
obtain
the
2's
complement.
Load
Complement
of
Address
in
Index
LAC +0535 (I, E)
Figure
5.3-66
This
instruction
loads
the
2's
complement
of
the
address
(21-35) of
storage
location
X
into
the
specified
index
register.
Execution
of
this
instruction
requires
an
E
cycle
to
obtain
the
word
from
storage.
The
address
portion
is
transferred
to
the
index
regis-
ter
by
way
of
the
adders
at
the
end
of
the
cycle,and,
to
obtain
the
2's
complement,
the
index
register
is
cycled
during
the
following
I
cycle.
Load
Complement
of
Decrement
in
Index
LDC
-0535
(I, E)
Figure
5.3-66
This
instruction
loads
the
2's
complement
of
the
decrement
field
(3-17) of
storage
location
X
into
the
specified
index
register.
Execution
of
this
instruction
is
identical
to
that
of LAC
except
that
the
SR
decrement,
instead
of
the
address,
goes
to
the
adders.
Load
Index
from
Address
LXA +0534 (1,
E)
Figure
5.3-66
This
instruction
loads
the
specified
index
register
with
the
contents
of
the
address
field
(21-35) of
storage
location
X
in
true
form.
Execution
of
this
instruction
is
identical
to
that
of
LAC,
except
that
the
complementing
operation
is
not
required.
126

Table of Contents

Questions and Answers:

Question and Answer IconNeed help?

Do you have a question about the IBM 7090 and is the answer not in the manual?

IBM 7090 Specifications

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