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IBM 7090 User Manual

IBM 7090
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The
address
of 00005
in
the
PC,
through
the
AR
and
MAR,
brings
the
next
instruction
to
the
SR
and
PRo
Decoding
the
PR,
the
CPU
operation
is
store
and
the
address--
SR
(21-35)
--at
which
to
store
is
00011.
The
PC
advances
to
00006. Sum C
in
the
AC,
be-
cause
of
decoding
store,
goes
to
the
SR
after
SR (21-35)
goes
to
the
AR
and
MAR.
Then
storage
accepts
SR
to
the
memory
data
register
(MDR)
and
stores
it
at
address
00011.
The
operation
is
now
complete
and
sum
C
is
stored
for
printing.
The
only
remaining
task
for
the
C 'pU
is
to
tell
channel
A
to
start
the
printer
and
to
give
channel
A
the
address
of
C.
The
next
instruction,
coming
from
00006
as
dictated
by
the
PC,
decodes
as
write
select.
The
PC
advances
to
00007.
Again,
as
in
read
select,
the
channel
and
unit
selection
is
in
the
address
field
of
the
instruction.
The
bit
configura-
tion
there
indicates
the
printer
on
channel
A.
Channel
A
acknowledges
the
selection
if
the
printer
is
ready.
This
frees
the
CPU
to
ask
for
another
instruction,
this
time
from
00007.
The
instruction,
decoded
in
the
PR,
directs
the
resetting
of
channel
A
registers
and
the
loading
of a
command
from
the
address
found
in
the
address
field
of
the
instruction.
In
this
case,
SR (21-35)
has
the
address
of
the
command.
The
address
goes
to
adders
3-17,
then
to
the
AR
and
MAR.
Storage
delivers
the
contents
of
this
address,
00013,
to
chan-
nel
A
instead
of
the
CPU
because
of
controls
set
up
by
the
PRo
By
this
time,
the
PC
had
advanced
to
00010,
so
when
channel
A
has
received
its
com-
mand,
the
CPU
receives
the
contents
of
00010
as
an
instruction.
Decoding
a
PR
of
zeros
causes
the
CPU
to
stop.
The
operation
code
of
zeros
is
called
halt
and
transfer.
If
the
CPU
should
be
restarted,
the
address
field
of
00010,
which
is
all
zeros,
would
go
to
the
PC
and
the
program
would
restart
at
00000.
The
role
of
the
CPU
in
A+B =
C,
print
C
is
now
ended.
However,
channel
A
still
has
to
print
C.
The
printer
is
started
and
channel
has
a
disconnect
command
in
the
operation
register,
a
word
count
of
one,
and
the
address
of
C--00011--in
the
CAC.
These
all
came
from
storage
location
00013
as
the
CPU
executed
the
instruction
at
00007.
Channel
sends
00011
from
the
CAC
to
the
MAR.
Sum
C
comes
back
to
the
DR,
and
the
WC
steps
to
zero.
As
soon
as
the
printer
is
ready
to
receive
C,
the
word
goes
from
the
DR
to
the
calculator
exit
and
is
printed.
Channel
A
is
also
finished
now,
and
A+B =
C,
print
C
has
been
accomplished.
If
you
have
followed
the
program
for
A
+B
=
C,
print
C,
carefully,
referring
to
Figure
2.3-1,
you
should
now
have
a
general
idea
of
the
operation
of
the
7090
system.
2.5.00
OTHER
COMPONENTS,
INSTRUCTIONS, AND COMMANDS
The
preceding
explanation
is
simplified,
and
many
components
and
functions
are
omitted.
Before
continuing
with
a
study
of
this
manual,
study
the
instructions
and
com-
mands
described
in
IBM
7090
Data
Processing
System
Reference
Manual,
Form
A22-6528.
Figure
2.5-1
shows
two
other
possible
configurations
of
the
CPU
instruction
word:
Figure
2.5-2
is
a
more
complete
representation
of
system
components.
These
figures
will
prove
helpful
in
studying
the
7090
Reference
Manual.
21

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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