Reference / Paper · 1964

CANDIDE: Overall Plan for Possible Developments of Linkage of the CETIS Analog and Digital Computers

NASA Technical Translation TT F-8591 (January 1964) of the 1963 EURATOM/CETIS report No. 33 by A. Riotte. The paper presents an overall development plan (project CANDIDE) for linking the CETIS analog and digital computers at the Joint Nuclear Research Centre, Ispra, Italy. Two linkage types are addressed: one-directional static linkage placing the analog computer under digital control via the APACHE programming code, and dynamic two-directional linkage using A/D and D/A conversion so the digital computer acts as a real-time function generator. Planned subprojects SATANAS and ATANASE are outlined, along with ancillary studies on automatic scaling, subroutine libraries, and time estimates for each development stage.

Manufacturer: NASA / EURATOM
System: CETIS hybrid computer complex (ADIOS analog + IBM 1620 digital); APACHE programming code
Author: A. Riotte
Year: 1964
Type: Reference / Paper
Language: English
Learning track: specific applications
Pages: 19
Credit: Translated for NASA by John F. Holman and Co. Inc. Original: CETIS Report No. 33, Centre Commun de Recherche Nucleaire, Etablissement d'Ispra, Italy, 1963.

CETIS hybrid computer complex (ADIOS analog + IBM 1620 digital); APACHE programming code
NASA / EURATOM
hybrid computing
analog-digital linkage
APACHE code
digital programming of analog computers

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CANDIDE: OTTERALL PLAN FOR P O S S I B L E DETELOPf/lENTS OF 4 LINKAGE OF T H E C E T I S ANALOG AND D I G I T A L COMPUTERS j / Z2 (NASA CR OR TMX OR AD NUMBER) A u. (CATEGORY) - T r a n s l a t i o n of CANDIDE Plan d 'ensemble s u r l e s d6velopements p o s s i b l e s du couplage des c a l c u l a t e u r s analogiques e t d i g i t a u x du C E T I W NATIONAL AE;RONAUTICS AND S P A C E ADMINISTRATION WASHINGTON January 1964 COIQ&TNAUT~m o p h m m DE L 1 ~ G I E ATOMIQUE-=TOM CANDIDE: O V m PLAN FOR POSSIBLE DEVELOPlMEfJTS OF LINKAGE OF THE CElllIS ANALOG AND DIGITAL COMPUTERS A. RIOTTE 1963 Centre Commun de Recherche Nuclkaire Etablissement d'Ispra Italie Centre Europken de Traitement des Informations Scientifiques-CEIS - CElfIS Report No. 33, 1963 ^..._._.._..,._._,I_ ........... .,. ..... ... . . .. . ... ~ ............. ............................ 1 ............................ r ....I ~ .....I---.-. .-.I._ ............................................. ........................................ comms . _-_. ) 1 % ntroduction ~ 1. Present Position of the APACHE Code . . . . . . . . . . . . . 2. Review of Numerical Inputs and Outputs Available on the Two Types of Computers . . . . . . . . . . . . . . . 21 1 3.1 Linkages in the digital-to-analogdirection . . . . . . . 6 6 1 3.1.1 3.1.2 SATANAS project ATANASE project . . . . . . . . . . . . . . . . . ................. ...................... 4.1 Automatic verification of analog function . . . . . . . . 4.1.1 Automatic maintenance . . . . . . . . . . . . . . 4.1.2 Static check processing . . . . . . . . . . . . . 4. Ancillary Studies ' I I / 10 10 10 12 4.2 Constitution of a library of subroutines in APACHE 2 . . 12 4.3 Special programs connected with problems to be solved . . 12 4.4 Mathematical analysis of the new tool . . . . . . . . . . 4.5 Application to the CARN project . . . . . . . . . . . . . 12 13 . Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . 13 ibliography . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 1 [ I CAKDIDE: OVERALL PLAN FOR POSSIBLE DEVELOPMENTS OF LINKAGE OF THE CETIS ANALOG AND DIGITAL C m B S flTMMARY a4 d g/ ,k .,.a,. The s t u d i e s required f o r development of linkages* between t h e CETIS analog and d i g i t a l computers are described. Two t y p e s o f linkage a r e distinguished: 4*ck.*+%z 1. One-directional s t a t i c or s t r u c t u r a l linkage by which t h e analog computer i s placed under t h e d i r e c t or i n d i r e c t c o n t r o l of t h e d i g i t a l computer f o r t h e set-up phase. The problem i s furnished t o t h e computer i n t h e form o f a d i g i t a l program i n APACHE code, and 2. Dynamic two-directional linkage. The d i g i t a l computer a f t e r a n a l o g - d i g i t a l conversion processes t h e analog values and r e s t o r e s o t h e r s by d i g i t a l analog conversion, thus a c t i n g as a f u n c t i o n generator. A study p l a n t o d i v i d e t h e t h e o r e t i c a l and pract i c a l work i n t o s t a g e s i s presented, w i t h t i m e e s t i mates. ?9- , Since t h e a s s o c i a t i o n of teams s p e c i a l i z i n g i n t h e two t y p e s of corn puters a t CETIS has a l r e a d y born f r u i t i n t h e form of t h e &ACRE code, t h e need arises f o r establishment of an o v e r a l l plan f o r development of a d i r e c t a n a l o g - d i g i t a l linkage. _*-_ I - For several years, t h e bringing t o g e t h e r of t h e two d i s c i p l i n e s has been attempted i n various ways, e i t h e r by considering t h e o r d i n a t o r as a p i g i t a l computer i n r e a l t i m e , simulating t h e p a r t of t h e problem prockssed d i g i t a l l y i n r e a l i t y ( c o n t r o l of machinery, f o r example, Ref. l), o r by s p l i t t i n g up t h e problem i n t o sequences o f successive analog schemas, a d i g i t a l memory connecting t h e preceding with t h a t which follows e f . 5 ) . Other methods have been i n v e s t i g a t e d : one of them which i s 11 known c o n s i s t s i n organizing a d i g i t a l computer as an analog comu t e r with a view t o p a r a l l e l functioning of t h e c i r c u i t s ( D i g i t a l D i f e r e n t i a l Analyzer). Attempts have been made a t d i g i t a l programing bef o r e analog set-up ( R e f s . 4, 8). F i n a l l y , i n t h e course of preliminary study from which t h e present r e p o r t d e r i v e s , t h e r e has been an opportun i t y t o become acquainted w i t h a p r o j e c t (Ref. 9 ) whose goals and aprs, b u t without -- s u f f i c i e,n t d e = o - m g n s x & P pa C so __X" '-19pc:d by /f' x * " C ___x p*."ni<*.cd 31' ,cfC..'d~i~D,,S I' / ~ _ - -_ ~ ~ ? O O P ? S tby--d . r - O * e e c l i & P s Iypod by- __ 2 d primarily t o exploit with The following study p l a n w a s e s t a b l i maximum e f f e c t i v e n e s s t h e analog complex e x i s t i n g a t CETIS and t o i n crease i t s p o t e n t i a l i t i e s and t h e r e l i a b i l i t y of i t s use by means of inkage w i t h t h e powerful neighboring d i g i t a l i n s t a l l a t i o n . . Present P o s i t i o n of t h e APACHE Code 3 APACHE 1 i s being used. It permits preparation of t h e setup and s t a t i c check of a problem on an analog computer by means of IBM 1620 ( R e f . 7). It must be regarded as a code f o r intra-CETIS use, permitting those who apply it t o draw from it experience t h a t i s r e q u i s i t e f o r cons t r u c t i o n of t h e d e f i n i t i v e APACHE 2 code. Indeed, although it f u n c t i o n s adequately within i n i t i a l l y f i x e d l i m i t s , it i s t o be wished t h a t two d i f f e r e n t types of codes w i l l not be s t a r t e d which r e f e r t o two stages of t h e same problem. Moreover APACHE 2 i n t h e course of d e f i n i t i o n a t t h e Computer Center w i l l respond t o requirements c l e a r l y more ambitious t h a n those imposed upon APACHE 1. Intended t o be used on IBM 7090, it w i l l allow: 1. D i r e c t processing of high order d i f f e r e n t i a l equations without breakdown i n t o equations of t h e f i r s t order, 2. Writing w i t h marked v a r i a b l e s , and 3. I n t r o d u c t i o n of subroutines corresponding t o l i b r a r y block d i a grams. The f i r s t condition w i l l r a d i c a l l y ease t h e w r i t i n g of t h e program. E t w i l l a l s o allow: I 1. I n a d d i t i o n t o processing of d a t a furnishing setup c o e f f i c i e n t s of t h e potentiometers and the s t a t i c check ( t h e s e already provided by APACHE I), an automatic addressing of t h e elements of t h e analog compute amplifiers, potentiometers, l o g i c a l fbnctions, nonlinearities,. 2. An optimizing of t h e b e t a f a c t o r , r e p r e s e n t i n g t h e r e l a t i o n s h i p of machine t i m e t o t h e independent variable of t h e problem, and 3. A p r e p a r a t i o n of s t a g e s of computation by p a r t i a l modifications of t h e program. F i n a l l y an adaptation of t h i s d e f i n i t i v e code for i t s use on IBM 1620 with punched card i n p u t s and outputs, i n d i r e c t addressing system an 40,000 memory p o s i t i o n s i s envisioned as of now, i n o r d e r t o permit a p o s s i b l e spread t o analog computer centers. Indeed, t h e s e c e n t e r s can contemplate a c q u i s i t i o n of such a machine t h a t would j u s t i f y i t s e l f by t h e s u b s t a n t i a l i n c r e a s e of power, r e l i a b i l i t y and speed of t h e i n s t a l l a tion. A l l t h a t precedes c o n s t i t u t e s t h e language permitting d i g i t a l processing of information b i t s contained i n t h e d a t a . The r e s u l t determines ...................................................................... .............................................. ................................ .................. 1 ...............--...... 3 - t h e choice of s p e c i a l s t r u c t u r e t h a t t h e analog computer assumes upon r e s o l u t i o n of t h e problem. It i s a c c e s s i b l e t o t h e u s e r i n form of a c o n t r o l r e g i s t e r which picks up t h e d a t a , a s s o c i a t i n g t o them a l l t h e r e q u i s i t e information (such as choice of s c a l e s , i n i t i a l values, s t a t i c check, d i s t r i b u t i o n by address of t h e operation t o t h e computers, e t c . ) . There remain t o b e s p e c i f i e d t h e various e x i s t i n g and nonexistent rgans t h a t w i l l support t h e p r a c t i c a l embodiment of t h i s s t r u c t u r e , and, t o s t a t e p r e c i s e l y what stages can reasonably be provided before t h e achieving of a two-way dynamic linkage. 2. Review of Numerical I n p u t s and Outputs Available on t h e Two Types of Computers The present computer materiel comprises analog and d i g i t a l computerg, of which t h e former have p o s s i b i l i t i e s of numerical command for c e r t a i n elements . 2.1 Analog computer The Analog Section i n s t a l l a t i o n comprises E l e c t r o n i c Associates 231 R with ADIOS console (Automatic D i g i t a l Input Output System). When a problem i s put on t h e machine, t h e d a t a i n p u t s are of various types. 2.1.1 Setup or pre-computation d a t a e.1.1.1 Value of t h e numerical c o e f f i c i e n t s The t a b l e of numerical c o e f f i c i e n t s corresponds t o t h e f u r n i s h i n g of parameter d a t a and i n i t i a l conditions. It can be introduced by perf o r a t e d t a p e (FRIDEN p e r f o r a t o r and r e a d e r ) , t h e code used being a 7channel code (Ref. 10). Setup of t h e block diagram 2.1.1.2 It corresponds t o t o p o l o g i c a l connection between u n i t s o f computat i o n and it i s achieved manually by i n t r o d u c t i o n of p i n s i n t h e hubs of t h e p a t c h board. Since t h e coordinates of t h e p o i n t s t o be connected are itssumed t o b e furnished by t h e program, t h e operation can be regarded a s ( 8 purely manual one. ~ ~ - - Setup of f u n c t i o n generators 2.1.1.3 The c o n s t i t u t i o n of present f u n c t i o n generators (DFG, pot padders) provides only manual setup on t h e potentiometer of p o i n t s determined by an a n a l y s i s of t h e furnished curves: mathematical or experimental func- -_ -_ ._ _ _ -__ tTons. I x ~ I I I . I - -- - - I 4 ns of two or more v a r i a b l e s can b e c a r r i e d by various procedures, depending upon t h e required precision, t o a fragment of t h e block diagram t h a t uses t h e e x i s t i n g u n i t s including f u n c t i o n gene r a t o r s , w i t h i n t h e range of t h e a v a i l a b l e materiel. 2.1.1.4 R e g i s t e r of various cases of computation . . : i, , j i It can b e characterized by modifications of parameters, of i n i t i a l conditions, of block diagram, of setup of f u n c t i o n generators. The f i r s t two cases occur w i t h t h e i n t r o d u c t i o n of a new perforated t a p e i n t h e ADIOS console, while t h e l a s t two n e c e s s i t a t e a manual i n t e r v e n t i o n . 2.1.2 R e s u l t s i n s t a t i c output When t h e 2 3 l R ’ s a r e stopped i n t h e course of computation, e i t h e r a t t h e end of a predetermined period or by comparison of a v a r i a b l e w i t h a preset value, t h e ADIOS console allows numerical readout, p r i n t e d by a typewriter, of values taken by a l l t h e variables i n play a t t h e moment o f h a l t i n g , and t h e i r t r a n s f e r on perforated t a p e according t o a reading program t h a t states t h e u n i t s o f which t h e output value i s desired. 2.1.3 R e s u l t s i n dynamic output I They are obtained i n a purely analog form: output voltage of t h e computer a m p l i f i e r s developing between + and - 100 V w i t h a n o p e r a t i o n a l frequency range l i m i t e d t o 100 cycles. 2.2 I < Arithmetical computers The customary i n p u t and output supports are: 1. Perf orated t a p e s (1620), 2. Punched cards (7090 and 1620 with extension), and 3. P r i n t e r or typewriter. 2.2.1 S t a t i c linkage t The u s e of punched cards for intermediate phases where t h e informat i o n support makes manual t r a n s p o r t p o s s i b l e w i l l be generalized. To e l i m i n a t e t h i s support, t h e d e f i n i t i v e stage w i l l n e c e s s i t a t e t h e r e a t i o n of d i r e c t transcoding apparatus, using e l e c t r i c s i g n a l s before card punching, b u t t h e communication path w i l l be a t t h e l e v e l of t h e punch and reader. .. ~ 5 ... 2.2.2 Dynamic linkage The solutions heretofore adopted of which we are cognizant all had he disadvantage of blocking the digital item for the benefit of the an item, in consequence of the direct access of the transcoders to the ory. To avoid this immobilization, communication ought to be effect the channel level, but with the possibility of calling from the analo side. It will thus be necessary to design a special channel system comprising a certain number of registers associated with analog-digital and digital-analog transcoders, and an operations coordinator (Figure 1). ' By this means, communication with the memory will not imraobilize the ' ,entire 7090 computer assembly but will enter into the sequence of programs in progress. t I 1 i E Figure 1. Junction between Analog Installation and IBM 7090 3. Definition of Contemplated Technical Stages In order to retain a constant check on the scope of obtained result and a clear view of the volume of research and of budgetary requirements - --_ ~ I ^ - - - 1 - x X X I -x x I- 1 1 _ 1 1 1 1 - ~ 1 1 - 6 involved by t h e development of t h e linkage, it a succession of w e l l defined stages. preferable t o e s t a b l i & A s has been seen, two l i n k a g e types are presented, bound t o t h e comp u t e r concept : 1 I [ : $ 1. A one-way d i g i t a l - a n a l o g linkage permitting automatic setup of t h e problem, which could b e described as an "analog s t r u c t u r e linkage," 2. A two-directional linkage i n which analog variables can be t r e a t e d by t h e d i g i t a l computer, which a f t e r processing of t h e s e d a t a can: a. b. E i t h e r a c t v i a t h e s t r u c t u r a l linkage, or Reintroduce new variables a t t h e l e v e l of t h e analog items. Up t o a c e r t a i n p o i n t t h e s e problems are independent. I n f a c t , w i t h t h e r e s t r i c t i o n of abandoning t h e s t r u c t u r a l l i n k a g e i n t h e second p o s s i b l e arrangement, and of not contemplating d i g i t a l p a r t i c i p a t i o n except as a s o p h i s t i c a t e d organ of analog computation, t h e l a t t e r could be developed before t h e former. W e w i l l however keep t h e order i n t h i s d i s c u s s i o n t h a t corresponds t o t h e growing closeness of t h e likkage, even i f i t s order m u s t be modiTied i n t h e course of a c t u a l embodiment. 1 ' I 3.1 Linkages i n t h e d i g i t a l - t o - a n a l o g d i r e c t i o n 3.1. l SATMAS p r o j e c t (Semi AuTomatic ANalog S e t t i n g ) 1 A f i r s t r a p i d l y a c c e s s i b l e embodiment i s t h e e x p l o i t a t i o n of i n f o r mation of address of elements furnished by APACHE 2, reducing t h e setup @f patchboards t o a purely manual operation. A panel w i t h luminous p o i n t s w i l l be c o n t r o l l e d by a r e l a y decoder s t a r t i n g from punched cards furnished by t h e program and i n d i c a t i n g t h e (start and t h e completion of each connection t o be e s t a b l i s h e d . A p a t e n t a p p l i c a t i o n f o r t h i s w i l l be f i l e d immediately. The inexpensive assemb l i n g has t h e advantage of development w i t h i n a reasonable time. Thou he automation thusobtained i s only a semi-automation i n which manipul i o n s t i l l occurs a t t h e l e v e l s of: Transfer of punched cards, and Se f t h e patchboard and i t s i n s t a l l a t i o n on t h e machine; it does a l r e a d permit t e s t i n g of t h e operation of t h e "address" p a r t of APACHE 2, and t h e a c q u i s i t i o n of experience for t h e succeeding phase. I n t h i s stage, t h e addressing c o n s i s t s simply i n t h e assignment of analog items accordi n g t o a v a i l a b i l i t y , a f t e r preliminary s e l e c t i o n of types of n o n l i n e a r i t i e s upon reduction of t h e program. A l i m i t e d number of simple r u l e s w i l l permit r a t i o n a l o r g a n i z a t i o n of a panel. _. . . _. . . .. . .-~ . 7 tant The r e l i a b i l i t y of setup w i l l be very much enhanced a t i m e saving w i l l r e s u l t from elimination o f e r r o r s i n t h i s phase of t h e work. On t h e o t h e r hand, t h e transcoder f o r perforated cards t o t a p e s t o t r a n s l a t e t h e d i g i t a l information coming from t h e APACHE 2 processing has ; t a l r e a d y been e f f e c t e d i n t h e form of an i n t e r n a l modification of t h e f ADIOS console (Ref. 10) and of an IBM 026 card punch used i n reading. 3.1.2 ATANME p r o j e c t (AuTomatic ANAlog SEtting) This s t a g e develops n a t u r a l l y i n p r i n c i p l e from t h e preceding one. This time without e x t e r n a l intervention, it i s a question of e f f e c t i n g complete setup of a problem w i t h command o r i g i n a t i n g i n e x p l o i t a t i o n of a d i g i t a l program. Figure 2 shows c l e a r l y t h e p o i n t s a t which it i s s u i t able t o introduce an automatic arrangement: patchboard and f u n c t i o n gene r a t o r s. For t h e s e l a t t e r a version designed by E l e c t r o n i c Associates should allow d i r e c t setup of t h e potentiometer slopes controlled by t h e more expensive ADIOS system (D.D.F.G. ) and occupying more space t h a n present f u n c t i o n generators. They have t h e advantage of being s u b s t a n t i a l l y a u t matic. I n f a c t t h e present v e r i f i c a t i o n by s t a t i c check only t a k e s i n t c account one p o i n t on t h e curve and manual setup r e q u i r e s a rigorous chec independent of t h e s t a t i c check. The problem of t h e automatic patchboard i s t e c h n i c a l l y much more d i f f i c u l t : a board r e p r e s e n t s a p o s s i b i l i t y of connections between outp u t s and i n p u t s of i t e m s whose number, taken without any r e s t r i c t i o n , approximates 3,OOO,OOO. Taken i n t h i s form, a commutation system i s p r a c t i c a l l y impossible t o achieve: but a more systematic study of t h e organization of a board makes apparent: exclusions, preferred s t r u c t u r e s , a breakdown of t h e block diagrams i n t o subunits connected by a small number of variables corresponding i n g e n e r a l e i t h e r t o a physical l o c a l i z a t i o n due t o t h e s t r u c t u r e proper of t h e u n i t t o be designed, or t o a l o c a l i z a t i o n due t c t h e mathematical processing (passage t o f i n i t e d i f f e r e n c e s i n a p a r t i a l d i f f e r e n t i a l equation system). I n advancing t h i s i d e a and t a k i n g i n t o account a c e r t a i n number of r e s t r i c t i o n s stemming from s t a t i s t i c a l s t u d i e s , t h e r e should emerge an automatic d i s t r i b u t o r of about 10,000 contacts, according t o preliminarg estimates. There i s a r e t u r n t o p o s s i b l e o r d e r s of magnitude; t h e use c r e l a y s or of a step-by-step arrangement i s imposed by t h e q u a l i t y of the connections t h a t i s t o assume t h e i n t e g r a l c h a r a c t e r of t h e transmissior of analog voltages. I 8 I Figure 2. "SATANAS" Pro je& - _ - .._. ._. - I n p a r a l l e l , t h e organization of t h e address code w i l l be completed t o t a k e i n t o account r e s t r i c t i o n s , exclusions and a r e l a t i v e optimization of t h e a p p l i c a t i o n of t h e computer elements. The f i r s t s t a g e of t h i s study w i l l c o n s i s t i n simulating on t h e IBM 7090 t h e various p o s s i b l e , arrangements of automatic patchboards and comparing t h e i r e f f i c i e n c y and! s i m p l i c i t y of p r i n c i p l e . A b a s i c redesign of t h e present computer s t r u c t u r e required by t h e exigencies of technology i s not ruled out. A t t h e conclusion of t b i s study a setup system w i l l be a v a i l a b l e t h a t i s completely f r e e d from t h e manual i n t e r v e n t i o n of t h e operator. Only t h e t r a n s f e r of punched cards w i l l be necessary (Figure 3). Figure 3. "AWNASE'' P r o j e c t . AuTomatic i--n g~ . _--_ ~ -ANAlog - ~ - ~ -S-a t- ~ x 1 - ~ L 9 B u t it i s w e l l t o s t r e s s t h e t e c h n i c a l d i f f i c u l t i e s presenting a m u l t i p l i c i t y of problems i n t h e development of t h e setup panel: contact q n a l i t y , command systems, q u a n t i t y of materiel, organization of t h e address system, p o s s i b l e p a r a l l e l manual i n t e r v e n t i o n , method of c o n t r o l , ( : , j t . 3.2 3.2.1 . , Two-way linkage . CRESSIDA p r o j e c t (Couplage REverSible S t a t I q u e D i g i t a l Analog) (Two-way s t a t i c d i g i t a l - a n a l o g linkage) I n t h e two preceding p r o j e c t s t h e t r a n s f e r of information from t h e d i g i t a l computer t o t h e analog input elements i s e f f e c t e d by means of t w successive supports, punched cards, perforated t a p e . Another p o s s i b i l i t y ought t o be t h e e l i m i n a t i o n of t h i s double t r a n s l a t i o n which can be considered as p r a c t i c a l l y independent. Indeed, a minimal modification of t h e ADIOS system m&es it p o s s i b l e f o r word-forword acceptance of coded information. This information can b e furnished d i r e c t l y without t h e perforated t a p e phase, s t a r t i n g from a p e r f o r a t o r assembly adjacent t o t h e reader; t h e furnished e l e c t r i c s i g n a l s would be s u b s t i t u t e d f o r t h e s i g n a l s furnished by t h e ADIOS reader. S i m i l a r l y , output d a t a from ADIOS would b e taken ahead of i t s p e r f o r a t o r system and r e f e r r e d t o t h e card punch. Human i n t e r v e n t i o n would be confined t o t h e carrying of cards between 1401 and t h e p e r f o r a t o r . I> 2 F i n a l l y a d e t a i l e d study of t h e e l e c t r i c s i g n a l s should make it poss i b l e t o develop an adapter t o assure d i r e c t s t a t i c connection w i t h chanl ne1 7090 as indicated i n Figure 1. 3.2.2 , ClWDIDE p r o j e c t (Couplage ANalog D I g i t a l DynamiquE) (Dynamic a n a l o g - d i g i t a l linkage) $ The problem i s t o cause a l l or p a r t of t h e analog values simultaneously i n play t o be communicated t o t h e d i g i t a l computer e i t h e r as a d i s c r e t e sample o r continuously. Several types of high speed converters already exist, f o r example, ADDALINK converters b u i l t by E l e c t r o n i c AssoI ciates and ADDAVERTEB (EPSCO), e t c . Thus t h e r e could be used: ’ i 1. E i t h e r a number of converters equal t o t h e analog channels t o b e t r a n s l a t e d t o d i g i t a l and v i c e versa (continuous l i n k a g e ) , or 2. Multichannel e l e c t r o n i c commutation devices each followed by a j s i n g l e converter (sampling l i n k a g e ) . I ! I A problem of o p e r a t i o n s s p c h r o n i z a t i o n i s added t o t h e problem of apparatus : r i n g t h e memories of t h e 7090, 1 . .- I $ .- _- --- -- - S e t t i n g i n t o operation t h e program t h a t answers t h e d i g i t a l par of t h e analog problem, and 1 3. Orders f o r i n i t i a t i o n and ending computation t r a n s f e r r e d t o t h e I 2. -_-- I _ _I I I I - I- I /7090 I A l l t h e above c o n s t i t u t e s only a bare o u t l i n e of t h e problem (speed ]synchronization, compatibility of s i g n a l s , study of s p e c i f i c programs, letc.) which should be examined i n d e t a i l . I I n f a c t t h i s dynamic linkage has already been used i n s p e c i a l cases / ( R e f . 5 ) b u t n o t w i t h p o s s i b l e d i g i t a l processing of t h e results and r e ' a c t i o n s on t h e block diagram s t r u c t u r e . The d e f i n i t i v e stage would conisist i n p u t t i n g simultaneously i n t o play t h i s dynamic l i n k a g e using t h e / d i g i t a l computer as a "super-generator of functions'' with extensive posj s i b i l i t i e s during t h e computer phase and hence a dependence upon t h e ana J o g i n s t a l l a t i o n , and as a " s t r u c t u r e c o r r e c t o r " t a k i n g i n t o account a icongeries of r e s u l t s t o prepare a new setup i n t h e s t a t i c phase, under ,the d i r e c t c o n t r o l of t h e d i g i t a l i n s t a l l a t i o n . f I The synoptic schema of t h e i n s t a l l a t i o n would then be as appears i n P i g u r e 4. 8 $ 14. A n c i l l a r y Studies 1 1 A whole s e r i e s of problems could be attacked i n p a r a l l e l with t h e / t e c h n i c a l s t u d i e s of linkage. Among o t h e r s t h e y relate to: I 1. Automatic v e r i f i c a t i o n of functioning of t h e analog materiel, 2. . C o n s t i t u t i o n of a l i b r a r y of subroutines i n APACHE 2, 3. S p e c i a l programs r e l a t e d t o problems t o be solved, 4. A mathematical a n a l y s i s of t h e new t o o l t h u s c o n s t i t u t e d i n i t s bwo aspects, s t r u c t u r a l linkage, dynamic linkage, and t h e i r a p p l i c a t i o n , land 5. S p e c i a l a p p l i c a t i o n of t h e linkage of p r o j e c t CARN. ih.1 Automatic v e r i f i c a t i o n of analog f u n c t i o n ib.1.1 Automatic maintenance To save t i m e i n t h e e f f e c t i v e u t i l i z a t i o n of analog machines, it i s o s s i b l e t o b r i n g up t h e problem of automatic maintenance. This could b by: I 1. A scheme f o r p u t t i n g t h e whole of t h e materiel i n t o play by I heans of a setup panel with s p e c i a l f i x e d wiring, 2. An ADIOS t a p e s e t t i n g up a l l t h e potentiometers from a s p e c i a l ~ A ~ ~ - p r o - p r ~ - ~ ~ - ~ ope ~ ra ~t x 1 5 .,--u~ ~ g ~ ' ~ ~ ~ I I I ' .' I I I I I' I I I *I I I I I ! I ' I ' Figure 4. Scheme of t h e P r i n c i p l e of P r o j e c t CANDIDE Black l i n e s : o r d e r s of s t a t i c linkage I I .....,........ '12 . . _._ _ ~ 3. 4. S p e c i a l elements as n o i s e d e t e c t o r , and < A series of s t a t i c t e s t s processed d i g i t a l l y ( p r o j e c t CRESSIDA) and f u r n i s h i n g t h e l i s t of d e f e c t i v e u n i t s . i T h i s embodiment can extend t o various kinds of m u l t i p l i e r s : a s p e c i a l method could be developed f o r f u n c t i o n generators w i t h manual setup. I 1 14.1.2 S t a t i c check processing I n p r i n c i p l e a l l t h e information b i t s of t h e s t a t i c check can be processed d i g i t a l l y . A comparison of obtained a c t u a l values and desired Values f o r d i f f e r e n t d e r i v a t i v e s could be done automatically. 1 1 1 I n any case t h i s operation would be of i n t e r e s t only i n s o f a r as a bethod could b e developed t h a t would provide a means f o r determining the jexact p o i n t s of sources of e r r o r . i 1 k.2 I 1 C o n s t i t u t i o n of a l i b r a r y of subroutines i n APACHE 2 The block diagrams corresponding t o c l a s s i c problems o f t e n reprokuced: k i n e t i c s of nuclear r e a c t o r s , p e r t u r b a t i o n f u n c t i o n s i n mathemat 1 p e a l form (Bessel function, attenuated or divergent sinusoids, exponenrtial superpositions, e t c . ), t r a n s f e r f u n c t i o n s i n general, could b e t h e jsub j e c t matter of l i b r a r y programs. S i m i l a r l y a mathematical processin6 pf d a t a such t h a t t h e breakup of f i n i t e d i f f e r e n c e s of equations t o parb i a l d e r i v a t i v e s i n c l a s s i c form could e n t e r i n t o t h i s framework. i4.3 t S p e c i a l programs connected w i t h problems t o be solved 1pf The present s u b j e c t i s too enormous t o b e attacked w i t h i n t h e l i m i t t h i s r e p o r t . A preliminary study of each problem w i l l be necessary 1 bequire t h e d e s i r e d experience. A s p e c i a l a p p l i c a t i o n of g r e a t importar bould be t h e operation of t h e f l o a t i n g decimal analog computer, i.e., a I preliminary setup t a k i n g i n t o account m a x i m a l known values of v a r i a b l e s ould automatically be corrected by t h e d i g i t a l computer after t h e i n i t j a l c u l a t i o n phase w i t h i n a l i m i t e d period t o reset t h e v a r i a b l e s w i t h ur known l i m i t s . On the o t h e r hand a lower l i m i t being e s t a b l i s h e d f o r thc r i n c i p a l v a r i a b l e s , any passing beyond t h i s l i m i t would give rise t o a ew s e t t i n g of t h e l i m i t s . ! --- ~ .4 Mathematical a n a l y s i s of t h e new t o o l ' i A new d i s c i p l i n e r e l a t e d t o t h e hybrid i n s t a l l a t i o n should b e devel I It should i n t e g r a t e t h e p r i n c i p a l problems not y e t resolved by @ped. L ____--I.-__. -.. ,,.,I_ l_^l_l l___..l.l..^. ............................................................... _..........^l^_.l___l_^l___I_^_-___~ ~ , c l a s s i c methods: generation of v a r i a b l e delays, opt on of c o e f f i b e n t s of d i f f e r e n t i a l equations from a known response, s y n t h e s i s of i ' t r a n s f e r f u n c t i o n s t a k i n g i n t o account t h e pulsed response of a system / ( R e f s . 13, 14). 14.5 Application t o t h e CARN p r o j e c t I I The most important a p p l i c a t i o n of t h e linkage technique i s c l e a r l y ,a c o n t r i b u t i o n t o Calcul Automatique de Reacteurs Nucleaires (Automatic /Computation of Nuclear Reactors) towards which development a l l t h e par$ i a l s t u d i e s a l r e a d y described ought t o be d i r e c t e d : optimization of Icoefficients, equation system synthesis, v a r i a b l e delays, processing of partial d e r i v a t i v e equations. A p o s s i b l e study of a d d i t i v e l i n k a g e of a / r e s i s t o r network (Ref. 1 2 ) t o t h e hybrid i n s t a l l a t i o n a l r e a d y described bought t o afford g r e a t e r p o t e n t i a l i t i e s f o r t h i s (simulation of r e a c t o r s /in theory t o two groups, heterogeneity of media, e t c . ) . it C e r t a i n new techniques concerning a c t i v e networks using a t i m e quan k i f i c a t i o n according t o a p r i n c i p l e derived from d i g i t a l methods ( R e f . 1 pould acquire f l e x i b i l i t y and speed by ltnkage with a d i g i t a l computer. t i s indeed p o s s i b l e t o a t t a c k p a r a b o l i c and hyperbolic equations with hese techniques w i t h an assured l o o p s t a b i l i t y from one s t a g e t o t h e tother, k 1 i b. Conclusions I i A s i n g l e l i n e of a t t a c k emerges immediately from t h e congeries of roblems posed by t h e linkage of t h e two types of computers. I n f a c t , he d i s t i n c t i o n between s t r u c t u r a l linkage and dynamic linkage permits a a r a l l e l development: t h e SATANAS p r o j e c t being immediately obtainable, I h i l e p r o j e c t s CRESSIDA and CANDIDE 1 can b e advanced independently of r o j e c t ATANASE concerning which fundamental questions of c o n s t r u c t i o n still exist. P B1 I l . l I n any case, t h e conjunction of CRESSIDA and CANDIDE 1 w i l l already f f e r extensive p o s s i b i l i t i e s i n t h e realm of automatic advance p r o j e c t s nd t h e study of i t s a p p l i c a t i o n t o CARN w i l l i n d i c a t e a l i n e of procedu 'n r e f e r e n c e t o s p e c i a l e f f o r t s t o b e c a r r i e d o u t f o r t h e d e f i n i t i v e r e a ' z a t i o n of CANDIDE 2. F i n a l l y , t h e a n a l y s i s of methods using passive and a c t i v e impedance networks and i n v e s t i g a t i o n of t h e i r p o s s i b l e linkage w i t h t h e two t y p e s bf computers envisioned i n t h i s r e p o r t w i l l be a b l e t o provide a s t i l l r e a t e r development of t h e t o o l s of a g r e a t Computer Center. It i s poss l e indeed t o imagine a meshed network r e p r e s e n t i n g a heterogeneous me&ium t o which would be applied conditions a t t h e l i m i t s and i n j e ct i o ns a i." --.--.--------- f I _ m m ......'_. ._... ". '. a,G O---Q--.--. 2-L .\ r) ...... ~ . " .._..... .... ..........'...'.. .........'...'...: 4 H I4 8 ; m a, 9d a, k cd Pi ... 0 -P a, . <:e c t h e nodes ("second member" terms) which would be variable as a f u n c t i o n of t i m e , furnished by an analog computer. The e x p l o i t a t i o n of t h e r e s u l t s (inventory of t h e f i e l d i n s p e c i a l areas, i n t e r p o l a t i o n being assured by t h e d i g i t a l computer which could--on condition of t h e compatibility of computing time--furnish new d a t a for t h e l i m i t i n g conditions to t h e analog computer. A r e t r o a c t i o n of t h e f i e l d on l i m i t i n g conditions would t h e n be f e a s i b l e . I n any case, t h e conjunction of t h e two computer d i s c i p l i n e s cannot b u t b e f r u i t f u l through t h e changes of viewpoint t h a t it r e q u i r e s of t h e respective specialists. Bibliography Combined Analog and D i g i t a l Systems, 1. McLeod, J. H. and Leger, R. M. Wiley, men and How, Instruments and Automation, V o l . 30, No. 6, June 1957. The General Trend Towards D i g i t a l Analogue Tech2. M a x w e l l , Paul niques. Actes d e s 2nd Journdes I n t e r n a t i o n a l e s de Calcul Analogique, Strasbourg, 1958. 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(APACHE l), Rapport EURATOM EUR 189.f, January 1963. 8. Witzel, T. and Wilson, J. L. D i g i t a l Computer-Programs Analog Solutions, V o l . 8, No. 6, June 1961. The Hybrid Computer. Automatic Data-Processing, 9. Diebold, J. e t al. J u l y 1961. ~10. Van Wauwe, A. Modifications apportges & 1'ADIOS en vue de l ' u t i l i s a t i o n du code APACHE 2 (Modifications of ADIOS for t h e Purpose of U t i l i z a t i o n of APACHE 2 Code). Rapport EURATOM, i n p r e s s . 11. Green, C., Debroux, A., D e l Bigio, G. P. and d'Hoop, H. Le code APACHE destine/ l a programmation d ' u n proklbme analogique a u moyen ~~~~~ ~~~ ~ ~ _ _ _ _ ^ _ _ ~ ~ - _ _ _ _ _ _ - . ___ __._.I. ~ _ . _ 1 _ - ~ , d'un calculateur digital (The APACHE Code Intended for Programming 1 of an Analog Problem by Means of a Digital Computer). Communicatio to the 3rd Journees Internationales de Calcul Analogique OPATIJA, September 1961. Karplus, W. A New Active-Passive Network Simulator for Transient / Field Problems. 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