R . F , Penne, D i r e c t o r , U n i v e r s i t y I n f o r m a t i o n P r o c e s s i n g
W,K, P r a t t , D i r e c t o r , E n g i n e e r i n g Computer L a b o r a t o r y and
Image P r o c e s s i n g I n s t i t u t e
J . P e p i n , Manager, E n g i n e e r i n g Computer L a b o r a t o r y and
Image P r o c e s s i n g L a b o r a t o r y
D. Smith, Manager, E n g i n e e r i n g Computer L a b o r a t o r y and
Image P r o c e s s i n g L a b o r a t o r y
U n i v e r s i t y of Southern C a l i f o r n i a
DISTRIBUTED PROCESSING
INTRODUCTION
The USC School of E n g i n e e r i n g employs d i s t r i b u t e d p r o c e s s i n g t o s u p p o r t
a wide v a r i e t y of s c i e n t i f i c and e d u c a t i o n a l computing a c t i v i t i e s . The b u l k
of t h e system r e s i d e s i n t h e E n g i n e e r i n g Computer L a b o r a t o r y (ECL). The
l a r g e s t a p p l i c a t i o n a r e a i s image p r o c e s s i n g .
T h i s p a p e r d e s c r i b e s b r i e f l y t h e o r g a n i z a t i o n of hardware components
and t h e i r u s e s i n a d i s t r i b u t e d p r o c e s s i n g environment.
C u r r e n t System
F i g u r e 1 d e p i c t s t h e d i s t r i b u t e d p r o c e s s i n g network c u r r e n t l y i n s t a l l e d
i n t h e USC School of E n g i n e e r i n g ( t h e two computers n o t y e t i n s t a l l e d a r e
shown w i t h d o t t e d l i n e s ) . For t h e most p a r t t h e network i s h i e r a r c h i c a l w i t h
s m a l l m i n i - c o m p u t e r s , l a b o r a t o r y i n s t r u m e n t s , and t e r m i n a l s a t t h e l o w e s t
l e v e l , l a r g e r m i n i s o r m i d i s a t an i n t e r m e d i a t e l e v e l , and maxi computers a t
the highest level.
The hub of t h e network i s a D i g i t a l Equipment C o r p o r a t i o n PDP 10 (DEC
1 0 ) . The DEC 10 i s a KI model, equipped w i t h 256K words of main memory
( a p p r o x i m a t e l y 1 m i l l i o n b y t e s ) , 4 IBM 33^0 d i s k d r i v e s (about 280 m i l l i o n
"bytes), and 2 IBM 3^20 t a p e d r i v e s . The TENEX o p e r a t i n g system i s used t o
c o n t r o l a l l computing a c t i v i t i e s .
The DEC 10 p e r f o r m s a number of d i f f e r e n t computing f u n c t i o n s i n t h e
network. A l a r g e p a r t of i t s a c t i v i t y i s devoted t o s e r v i c i n g s t a n d a r d time
s h a r i n g t e r m i n a l s whose u s e r s p e r f o r m a v a r i e t y of f u n c t i o n s such a s t e x t
e d i t i n g , s t a t i s t i c a l a n a l y s i s , and computional a c t i v i t i e s . The e x e c u t i o n of
image p r o c e s s i n g r o u t i n e s and c r o s s assembling f o r t h e mini-computers i n t h e
network a r e o t h e r i m p o r t a n t computing f u n c t i o n s handled by t h e DEC 10,
Three mini-computers a r e connected d i r e c t l y t o t h e DEC 10 and may be
t h o u g h t of a s b e i n g i n t h e n e x t l e v e l of t h e d i s t r i b u t e d p r o c e s s i n g network.
The I n t e r f a c e Message P r o c e s s o r (IMP) connects t h e DEC 10 and s u b s i d a r y e q u i p ment t o t h e ARPA network (ARPANET). The IMP, augmented by a Terminal I n t e r f a c e P r o c e s s o r ( T I P ) , p e r m i t s t e r m i n a l u s e r s and l a b o r a t o r y m i n i s a t USC t o
a c c e s s a wide v a r i e t y of computing systems, i n c l u d i n g an ILLIAC IV, CDC 7600,
and an IBM 3 6 0 / 9 1 . I n t h i s mode t h e DEC 10 a t USC can be t h o u g h t of a s an
i n t e r m e d i a t e - s i z e system which could p a s s more demanding computing workloads
t o more p o w e r f u l p r o c e s s o r s i n t h e ARPANET,
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383
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TERMINALS
ANNENBERG
SCHOOL OF
COMMUNICATION
BIOMEDICAL
ENGINEERING
USC SCHOOL OF ENGINEERING
DISTRIBUTED COMPUTING NETWORK
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MARCH 26, 1975 UPDATE
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I n o t h e r words t h e d i s t r i b u t e d network a t USC i s a c t u a l l y p a r t of a
l a r g e r d i s t r i b u t e d network, namely, t h e ARPANET, t h e c u r r e n t computing f a c i l i t i e s of which a r e shown i n F i g u r e 2 .
The IMP a l s o a l l o w s u s e r s a t o t h e r nodes on t h e ARPANET t o a c c e s s t h e USC
ne-toork. P l a n n i n g h a s begun f o r USC t o become a c e n t e r f o r image p r o c e s s i n g
u s i n g i t s f a c i l i t i e s and t h o s e of t h e ARPANET. U s e r s around t h e c o u n t r y would
be a b l e t o a c c e s s t h e images and s p e c i a l image p r o c e s s i n g equipment i n s t a l l e d
i n t h e USC Image P r o c e s s i n g I n s t i t u t e . Large computing problems would be
r o u t e d t o t h e p r o p e r p r o c e s s o r i n t h e ARPANET t o t a k e advantage of d i f f e r e n t
hardware c h a r a c t e r i s t i c s a s much a s p o s s i b l e .
As i n d i c a t e d i n F i g u r e 3 ARPANET u s e r s would u t i l i z e a f r o n t end imaging
system (FEIS) a t USC t o e x p e d i t e t h e i r image p r o c e s s i n g a c t i v i t i e s . FEIS w i l l
make u s e of t h e e x i s t i n g ARPANET s t r u c t u r e on a dynamic b a s i s t o a l l o c a t e
s c a n n i n g , number c r u n c h i n g , d i s p l a y t r a n s p o r t i n g , e t c . r e s o u r c e s of t h e n e t work f o r s p e c i f i c image p r o c e s s i n g job r e q u i r e m e n t s . The system would be
t r a n s p a r e n t t o t h e u s e r , i n t h e sense t h a t he would n o t need i n t i m a t e knowledge
of r e s o u r c e s a v a i l a b l e on t h e network, n o r would t h e u s e r be r e q u i r e d t o have
an i n t i m a t e knowledge of e x i s t i n g image p r o c e s s i n g s o f t w a r e , p r o t o c o l s , o r
network p r o c e d u r e s .
The f u n c t i o n s of t h e IMP and t h e TIP i n t h e ARPANET a r e w e l l documented
and w i l l n o t be covered i n t h i s p a p e r .
R e f e r r i n g back t o F i g u r e 1 t h e o t h e r two mini-computers connected d i r e c t l y
t o t h e DEC 10 a r e a PDP 11/10 and a PDP l l / k O . Both computers a r e connected t o
t h e DEC 10 mainframe t h r o u g h a d e v i c e c a l l e d a DL 10 which p e r m i t s each mini
t o a c c e s s an e x c l u s i v e p o r t i o n of t h e DEC 10 memory d i r e c t l y w i t h o u t e x e c u t i n g
input/output instructions.
The PDP 11/10 i s devoted t o h a n d l i n g and c o n t r o l l i n g communications between
asynchronous t e r m i n a l s and t h e DEC 10. As i n d i c a t e d i n t h e diagram i t i s
c u r r e n t l y c o n f i g u r e d t o s u p p o r t 48 l i n e s w i t h each l i n e o p e r a t i n g a t up t o 9,600
b a u d . The PDP 11/10 p e r f o r m s such o p e r a t i o n s a s l i n e s c a n n i n g , c h a r a c t e r
a s s e m b l i n g and d i s a s s e m b l i n g , b l o c k i n g and d e b l o c k i n g , e r r o r checking, r e t r a n s m i s s i o n of bad b l o c k s , e t c .
Most of t h e d e v i c e s connected t o t h e PDP 11/10 a r e k e y - d r i v e n CRT t e r m i n a l s
o p e r a t i n g a t 2,4-00 b a u d . I n a d d i t i o n a PDP 11/4-0 and a g r a p h i c s t e r m i n a l cont r o l l e d by a PDP 1 1 / 1 0 , a r e a l s o connected t o t h i s communications c o n t r o l l e r .
The o t h e r mini-computer connected d i r e c t l y t o t h e DEC 10, t h e PDP 1 1 / 4 0 ,
p e r f o r m s a wide v a r i e t y of f u n c t i o n s i n t h e d i s t r i b u t e d system. I t s primary
job i s t o handle synchronous communications between t h e DEC 10 and o t h e r
devices.
A System 3^0/44 i s l o c a t e d i n t h e same room a s t h e DEC 10 and i s connected
v i a t h e PDP 1 0 / 4 0 . Among o t h e r t h i n g s t h e 360/44- h a n d l e s a l l p r i n t i n g and card
r e a d i n g o p e r a t i o n s , r e l i e v i n g t h e DEC 10 of t h o s e f u n c t i o n s . I n a d d i t i o n t o
an IBM 1403 P r i n t e r and an IBM 2501 Card Reader, t h e Model 44 i s equipped w i t h
5 Mohawk d i s k d r i v e s (IBM 2314 e q u i v a l e n t ) , and 2 IBM 3420 magnetic t a p e d r i v e s .
Located about i of a m i l e away on t h e USC campus i s an IBM 370/158, which
s u p p o r t s r e s e a r c h , i n s t r u c t i o n a l , and a d m i n i s t r a t i v e computing. Many 158 j o b s
a r e s u b m i t t e d and p r i n t e d u s i n g t h e Model 44 a s an RJE s t a t i o n . Communications
between t h e PDP 11/40 and t h e Model 158 a r e performed over an i n f r a r e d , Optran,
l i n k . I n t h i s mode t h e PDP 1 J / 4 0 s i m u l a t e s an IBM 2701.
The Model 44 i s a l s o used f o r a v a r i e t y of computing f u n c t i o n s i n a s t a n d a l o n e manner. Many j o b s , w r i t t e n mostly i n FORTRAN, a r e r u n f o r i n s t r u c t i o n a l
-
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(F.T.P.)
u> ac
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IMAGE
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ARPA picture - typical mode bf operation.
land r e s e a r c h p u r p o s e s .
At t h i s time a n o t h e r s t a n d a r d RJE s t a t i o n i s remotely connected t o t h e
PDP 11/kO, which p r o v i d e s - a HASP i n t e r f a c e t o t h e t e r m i n a l .
The Hewlett Packard 2100 ( F i g u r e
d i r e c t l y connected t o t h e PDP l l A O ,
i s p r e s e n t l y h a n d l i n g a l l of t h e image p r o c e s s i n g d e v i c e s l o c a t e d i n t h e Image
P r o c e s s i n g I n s t i t u t e . As i n d i c a t e d i n F i g u r e 5 t h e s e d e v i c e s c o n s i s t of A/D
and D/A. c o n v e r t e r s , a f l y i n g - s p o t s c a n n e r , m i c r o d e n s i t o m e t e r , image d i s s e c t o r ,
and f a c s i m i l e p r i n t e r . The HP-2100 p e r f o r m s c o n t r o l , d a t a a c q u i s i t i o n , e d i t i n g ,
and computing f u n c t i o n s i n t h i s h i e r a r c h i c a l network of computing d e v i c e s .
One o t h e r mini-computer, a PDP 11/10, i s connected t o t h e 11/kO and i s
used p r i m a r i l y f o r development p u r p o s e s .
Future Plans
I n t h e n e a r f u t u r e a PDP l l / l O and 11/20, shown w i t h d o t t e d l i n e s i n
F i g u r e 1 , w i l l be added t o t h e o v e r a l l system. The PDP l l / l O w i l l be u s e d i n
t h e USC Annenberg School of Communications f o r t e r m i n a l m u l t i p l e x i n g . The
PDP 11/20 i s ' used i n t h e -Biomedical E n g i n e e r i n g Department f o r l a b o r a t o r y
purposes.
At p r e s e n t t h e HP-2100 i s overloaded due t o t h e p r o c e s s i n g demands made
by t h e image p r o c e s s i n g equipment. Some of t h e s e f u n c t i o n s w i l l be moved t o
t h e PDP 1 1 / 1 0 , now usedi f o r development. This i n e f f e c t d i s t r i b u t e s t h e p r o c e s s i n g l o a d and makes; t h e system l e s s dependent on one d e v i c e .
S t e p s a r e a l s o b e i n g t a k e n t o s h i f t f u n c t i o n s i n case c e r t a i n components
of t h e system go down. I f t h e DEC 10 f a i l s , f o r example, t h e HP-2100 w i l l be
a b l e t o f u n c t i o n a s a h o s t system, o b v i o u s l y , i n a degraded f a s h i o n .
I t i s p h y s i c a l l y p o s s i b l e t o g e n e r a t e d a t a a t t h e l o w e s t l e v e l , say w i t h
an image p r o c e s s i n g d e v i c e , and have i t p r o c e s s e d by any computer system on t h e
ARPANET, i n c l u d i n g such machines a s UlilAC 1 IV, a CDC 7600, o r a 360/91. S o f t ware i s b e i n g developed t o accomplish t h a t f u n c t i o n .
Summary*
D i s t r i b u t e d computing i s indeed b e i n g performed i n t h e School of E n g i n e e r i n g a t t h e U n i v e r s i t y of Southern C a l i f o r n i a . While t h e a p p l i c a t i o n s a r e
s c i e n t i f i c research r a t h e r than administrative the p r i n c i p l e s are b a s i c a l l y
t h e same. Mini-computers a r e used t o c o l l e c t , e d i t , and massage d a t a . The
d a t a i s t h e n r o u t e d t h r o u g h h i g h e r - l e v e l m i n i s t o l a r g e r computers f o r f u r t h e r
processing.
r
-
388
-
Image p r o c e s s i n g l a b o r a t o r y c o m p u t e r / c o n t r o l l e r f a c i l i t i e s .
I m a g e p r o c e s s i n g d i g i t i z a t i o n and
display
devices.
Figure 5
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