A Computer Utility for Interactive Instrument Control - ACS Symposium

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A Computer Utility for Interactive Downloaded by UNIV OF CALIFORNIA SANTA BARBARA on April 3, 2018 | https://pubs.acs.org Publication Date: June 1, 1975 | doi: 10.1021/bk-1975-0019.ch006

Instrument C o n t r o l * PAUL DAY Argonne National Laboratory, Argonne, Ill. 60439

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INTRODUCTION

With few exceptions, laboratory automation has proceeded by the interfacing of a mini-computer to each instrument that requires some type of real-time service; data acquisition, experiment control and/or the analysis of an on-going experiment. To those willing to invest considerable programming effort for each system or those whose needs may be satisfied by a commercially available package, this approach appears attractive. However, limited system f l e x i b i l i t y is the price paid for such systems, which price is derived from the inherent limitations of mini-systems; 16 b i t word size, fixed system resources, custom tailored programs (not modular), inherent difficulty of program development on a teletype, and unavailability of the computer for experiment control during code generation. The recent trend toward interconnecting several minis together into a network overcomes the limitations of fixed system size and provides the possibility of generating new code while real-time service is being provided. However, there is a class of instruments which require, and others which could greatly benefit by, real-time support which included the storage and analysis of large amounts of data (25K bytes/sec.) using such routines as fast fourier transformations, multi-point smoothing, least squares analysis and

*Work performed under the auspices of the U. S. Energy Research and Development Administration. 85 Lykos; Computer Networking and Chemistry ACS Symposium Series; American Chemical Society: Washington, DC, 1975.

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matrix manipulation. T h i s type o f s u p p o r t cannot g e n e r a l l y be p r o v i d e d by a mini-computer network u n l e s s a computer w i t h s i g n i f i c a n t l y more c a p a b i l i t y than a m i n i i s connected t o t h e network. T h i s computer s h o u l d p r o v i d e s u f f i c i e n t s t o r a g e c a p a c i t y and c o m p u t a t i o n a l a b i l i t y (32 and 64 b i t f l o a t i n g p o i n t a r i t h m e t i c ) t o p e r m i t t h e r e a l - t i m e e x e c u t i o n o f 20 t o 30K word FORTRAN programs, and i t c o u l d f u r t h e r i n c r e a s e s c i e n t i f i c p r o d u c t i v i t y i f a l l t h e f i n a l a n a l y s i s f o r each experiment c o u l d be performed on the same system. Rather than a network, our approach i s more analogous t o an o c t o p u s , i n which a l l r e a l - t i m e s u p p o r t i s p r o v i d e d by d i r e c t c o n n e c t i o n t o a c e n t r a l computer. A c a r e f u l study o f the r e a l - t i m e r e q u i r e m e n t s o f our C h e m i s t r y D i v i s i o n i n 1967 i n d i c a t e d t h a t a c e n t r a l computer w i t h s u i t a b l e hardware f e a t u r e s , p r o p e r l y c o n t r o l l e d by an o p e r a t i n g system, c o u l d p r o v i d e a l l the advantages o f a l a r g e computer w i t h o u t s a c r i f i c i n g the i s o l a t i o n advantage o f t h e mini-computer i n t h e l a b o r a t o r y {!) . The o p e r a t i n g system must u t i l i z e t h e s e hardware f e a t u r e s i n a manner which w i l l p r o v i d e each u s e r w i t h t h e l e v e l o f r e a l - t i m e and o t h e r s e r v i c e r e q u i r e d t o run h i s experiment, w h i l e a t t h e same time i n s u r i n g a l e v e l o f d a t a and program i n t e g r i t y e n j o y e d by the i s o l a t e d mini-computer u s e r . To d a t e i t has not been n e c e s s a r y t o enhance our c e n t r a l comp u t e r ' s s e r v i c e by t h e a d d i t i o n o f a mini-computer between t h e c e n t r a l computer and t h e remote i n s t r u m e n t . However, some o f our remote i n t e r f a c e s do p e r f o r m c o m p u t e r - l i k e f u n c t i o n s which i n t e r a c t w i t h an i n s t r u ment on a m i c r o s e c o n d time s c a l e . At f i r s t g l a n c e , t h e i s o l a t e d m i n i - s y s t e m has t h r e e advantages o v e r a l a r g e r system ( i n c l u d i n g a m i n i - n e t w o r k ) : i s o l a t i o n i n s u r e s no c o m p e t i t i o n f o r r e s o u r c e s ; d a t a and program i n t e g r i t y are as good as the s t a n d - a l o n e s o f t w a r e package; s i n c e hardware f a i l u r e r a t e i s somewhat p r o p o r t i o n a l t o t h e number of components i n a system, t h e m i n i w i l l be o u t o f service less often. However, our system has demons t r a t e d t h a t i t i s p o s s i b l e t o meet t h e above s e r v i c e and i n t e g r i t y a s p e c t s . The o n l y d i s a d v a n t a g e o f our c e n t r a l system i s a hardware f a i l u r e r a t e o f about once i n 20 days compared t o m i n i s which o f t e n run f o r many months w i t h o u t f a i l u r e . However, our o n - l i n e u s e r s c o n s i d e r t h i s i n s i g n i f i c a n t compared t o t h e f o l l o w i n g advantages o f our c e n t r a l system: 1.

The system i s o f s u f f i c i e n t s i z e and speed t o p e r f o r m most d a t a a n a l y s i s i n r e a l - t i m e o r a t

Lykos; Computer Networking and Chemistry ACS Symposium Series; American Chemical Society: Washington, DC, 1975.

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the c o m p l e t i o n o f an experiment. In the r a r e case t h a t more computing c a p a c i t y i s r e q u i r e d , 9 - t r a c k magnetic tape i s used f o r d a t a t r a n s f e r t o a l a r g e r computer. Dynamic s h a r i n g p r o v i d e s more r e s o u r c e s (CPU, c o r e , d i s k , magnetic tape) per experiment f o r a g i v e n c a p i t a l investment. F a s t program g e n e r a t i o n and debugging w i t h h i g h speed c a r d r e a d e r and l i n e p r i n t e r , a l o n g w i t h t h e use of modular programming t e c h n i q u e s makes program u p g r a d i n g easy enough t o keep up w i t h the r e s e a r c h s c i e n t i s t ' s changing needs. A t l e a s t seven of our o n - l i n e experiments a r e c o n s i d e r e d s t a t e - o f - t h e - a r t systems. Time-shared e x e c u t i o n of 25K word FORTRAN programs i n r e a l - t i m e . Batch e x e c u t i o n o f up t o 40K word programs f o r f i n a l a n a l y s i s . O n - l i n e keyboard d i s p l a y s and i n t e r a c t i v e g r a p h i c s r u n n i n g a t 9600 baud f o r w o r k i n g with data. D i s k s t o r a g e (75 megabytes) f o r d a t a (FORTRAN a c c e s s i b l e ) , programs and program o v e r l a y storage. Open-shop b a t c h - p r o c e s s i n g p e r m i t s o n - l i n e u s e r s t o d e v e l o p and debug t h e i r own FORTRAN programs which then have d i r e c t a c c e s s t o t h e i r data. Only a s m a l l programming s t a f f i s r e q u i r e d . A programming investment of 15 man-years has completed t h e o p e r a t i n g system and a p p l i c a t i o n s programs f o r 21 o n - l i n e e x p e r i m e n t s . An a d d i t i o n a l 8 man-years was i n v e s t e d i n t h e d e s i g n and c o n s t r u c t i o n o f the hardware i n t e r faces .

A l l c o n t r o l and o r g a n i z a t i o n a l a s p e c t s o f the System were d e s i g n e d , coded and implemented by our Chemist r y D i v i s i o n (2) . The f o l l o w i n g Xerox s o f t w a r e was i n t e r f a c e d t o t h e system; l o a d e r (BCM), assembler (SYMBOL), c o m p i l e r (FORTRAN IV-H) and FORTRAN r u n - t i m e / a r i t h m e t i c s u b r o u t i n e package. The c e n t r a l f a c i l i t y has been s e I f - r u n n i n g (no computer o p e r a t o r ) f o r over f i v e y e a r s 24 hours/day, 7 days/week w i t h t h e e x c e p t i o n of 8 h o u r s : 4 hours o f p r e v e n t i v e maintenance f o l l o w e d by 4 hours o f System development each week. The s y s tem i s c o n t i n u a l l y e v o l v i n g t o s u p p o r t new p e r i p h e r a l s (disks, i n t e r a c t i v e t e r m i n a l s , array processors, etc.) and t o p r o v i d e new s e r v i c e s as t h e needs a r i s e . Prov i s i o n s have been b u i l t i n f o r a u t o m a t i c r e c o v e r y from power f a i l u r e s , t o r e s t a r t f a u l t y p e r i p h e r a l s and t o cease u s i n g f a u l t y memory when d e t e c t e d . System uptime



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averages 157 hours p e r week w i t h one system c r a s h (down time averages about 40 minutes) about e v e r y 10 days ( h a l f a r e hardware r e l a t e d and t h e o t h e r system s o f t ware) . Automatic r e s t a r t f o r u s e r s i s a v a i l a b l e a f t e r weekly maintenance or a c r a s h . D a i l y c o p y i n g t o mag n e t i c tape o f a l l program and d a t a f i l e s s t o r e d on the d i s k s and RAD (Rapid Access Device - f i x e d head p e r track disk) insures users against c a t a s t r o p h i c f a i l u r e . A p a r t i a l l o s s o f d a t a c o l l e c t e d o v e r s e v e r a l hours has o c c u r r e d t h r e e times i n f i v e y e a r s as a r e s u l t o f h a r d ware f a i l u r e . II.

System S e r v i c e s

Computer C o n f i g u r a t i o n . The p r e s e n t computer conf i g u r a t i o n (Table I) has been i n c r e m e n t a l l y expanded from a 24K word system, w i t h o u t d i s k , s u p p o r t i n g 8 experiments t o t h e p r e s e n t system s u p p o r t i n g 21 e x p e r i ments and s i x independent g r a p h i c s / k e y b o a r d t e r m i n a l s . Sigma 5

CPU

Memory MIOP (2) CIOP Disk RAD ( f i x e d - h e a d d i s k ) 9 - t r a c k mag tape (2) Card Reader Line Printer Card Punch Paper Tape Digital Plotter TABLE I .

Central Processing Unit/ floating point arithmetic 56K 32 b i t words p l u s p a r i t y 750K b y t e s / s e c . bandwidth, 32 channels 21 110 baud t e l e t y p e , 2 1200 & 8 9600 baud t e r m i n a l s 251K b y t e s / s e c . t r a n s f e r , 25 megabytes χ 3 s p i n d l e s 170 K b y t e / s e c , 6 megabytes 60 K b y t e s / s e c , 800 b p i 1500 cpm 650 1pm 300 cpm 120 cps r e a d e r : 300 cps Punch: CALCOMP 565

Hardware C o n f i g u r a t i o n

Data T r a n s f e r . A l l u s e r and system d a t a i s han d l e d by i n p u t / o u t p u t hardware (MIOP) t h a t i n t e r a c t s with a l l devices running c o n c u r r e n t l y ; being capable of t r a n s f e r r i n g d a t a a t an aggregate r a t e of 750K b y t e s / sec. Thus, a d e v i c e seldom w a i t s more than a few mi c r o s e c o n d s f o r t r a n s f e r of a datum a f t e r i t s i g n a l s t h e MIOP t h a t i t i s r e a d y . Each u s e r ' s d a t a i s moved d i r e c t l y between h i s a s s i g n e d program c o r e memory and a d e v i c e ; t h e r e i s no system overhead r e q u i r e d beyond the time r e q u i r e d f o r MIOP t r a n s f e r .



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Real-Time Response. A s o f t w a r e p r i o r i t y i s a s s o c i a t e d w i t h each program c o n t r o l l i n g an i n t e r f a c e d i n strument. These p r i o r i t i e s a r e a s s i g n e d on t h e b a s i s o f i n s t r u m e n t r e q u i r e m e n t s a t system b o o t - i n t i m e . Upon r e c e i p t o f a r e q u e s t f o r program e x e c u t i o n (e.g. u s e r ' s d e v i c e s i g n a l s "done"), t h e u s e r ' s r e a l - t i m e program w i l l commence e x e c u t i o n a f t e r a time l a p s e t h a t depends on i t s p r i o r i t y . The h i g h e s t p r i o r i t y program w i l l commence e x e c u t i o n w i t h i n 160 microseconds, whereas the l o w e s t p r i o r i t y may not s t a r t e x e c u t i o n u n t i l up t o 200 m i l l i s e c o n d s l a t e r , i f one o r more h i g h e r p r i o r i t y programs a r e c u r r e n t l y " r e a d y - t o - r u n " . A s i m p l i f i e d r e a l - t i m e e x e c u t i o n s e r v i c e c y c l e may be r e p r e s e n t e d by t h e f o l l o w i n g : 1. Program r e q u e s t s a system s e r v i c e (e.g. s t a r t r e a d i n g d a t a from my d e v i c e ) 2. Program c a l l s e n d - o f - s e r v i c e (EOS) (program has n o t h i n g t o do u n t i l d a t a t r a n s f e r i s complete) 3. An MIOP i n t e r r u p t f o r t h i s d e v i c e i n d i c a t e s t r a n s f e r complete 4. Program p r o c e s s e s d a t a 5. Proceed t o s t e p "1" Custom Designed C o n t r o l Programs. Even though our e n g i n e e r s have e s t a b l i s h e d a b a s i c i n t e r f a c e d e s i g n and our programmers have d e v e l o p e d e f f e c t i v e t e c h n i q u e s f o r a c q u i r i n g d a t a and c o n t r o l l i n g i n s t r u m e n t s , each new system i s custom d e s i g n e d a t a l e v e l which w i l l b e s t s e r v e the u s e r ' s c u r r e n t and p r o j e c t e d needs. A command language i s e s t a b l i s h e d w i t h which the u s e r can e a s i l y communicate w i t h h i s programs i n a n a t u r a l manner. Program prompts a r e p r o v i d e d (e.g. "how many scans") so the u s e r does not have t o memorize an unfami l i a r mneumonic scheme. While our programming s t a f f d e s i g n s and w r i t e s t h e d a t a a c q u i s i t i o n and i n s t r u m e n t c o n t r o l p o r t i o n s of t h e package, u s e r s f a m i l i a r w i t h FORTRAN may code and use t h e i r own FORTRAN programs f o r r e a l - t i m e p r o c e s s i n g and/or f i n a l a n a l y s i s . User Communication and C o n t r o l . Human communicat i o n w i t h the computer system i s p r o v i d e d a t each r e mote e x p e r i m e n t a l s i t e v i a a KSR33 t e l e t y p e . At system b o o t - i n t i m e , i n p u t r e q u e s t s are i n i t i a t e d t o a l l comm u n i c a t i o n s t e r m i n a l s . A t any subsequent time, a u s e r may l o g - o n t o the system; a t which time s u f f i c i e n t c o r e memory space i s a s s i g n e d f o r t h e c o r e r e s i d e n t p o r t i o n o f h i s s p e c i f i c i n s t r u m e n t c o n t r o l program and i n t e r a c t w i t h h i s i n s t r u m e n t through t h i s program. Some o f the remote s i t e s a l s o have i n t e r a c t i v e g r a p h i c s t e r m i n a l s . In a d d i t i o n , s e v e r a l g r a p h i c s t e r m i n a l s and keyboard



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d i s p l a y s are s t r a t e g i c a l l y l o c a t e d f o r s h a r e d use. A u s e r may s i m i l a r l y l o g - o n and i n t e r a c t w i t h h i s graphi c s and/or computation programs from t h e s e t e r m i n a l s . The system p r o v i d e s the u s e r w i t h complete c o n t r o l of h i s i n s t r u m e n t i n t e r f a c e through the c o n s t r u c t i o n and e x e c u t i o n of any I/O command sequence t h a t can be e x e c u t e d by the MIOP and h i s d e v i c e . This permits the b u f f e r i n g of d a t a i n t o a u s e r ' s c o r e a r e a , w i t h i n t e r rupt i n d i c a t i o n s being passed t o the user's c o n t r o l program as each b u f f e r f i l l s , w h i l e t h e MIOP may initiate f u r t h e r d a t a t r a n s f e r i n t o another u s e r - s p e c i f i e d a r e a w i t h i n l e s s than 10 microseconds a f t e r a b u f f e r fills. System i n t e g r i t y i s i n s u r e d by c h e c k i n g f o r c o r e bounds v i o l a t i o n b e f o r e an I/O o p e r a t i o n i s i n i t i a t e d on the u s e r ' s a s s i g n e d d e v i c e . Mass S t o r a g e Usage. The system was d e s i g n e d t o maximize d a t a t h r o u g h p u t . T h e r e f o r e , d i s k (and RAD) f i l e s t r u c t u r e s were s i m p l y d e s i g n e d t o p r o v i d e random a c c e s s i n r e c o r d s i z e s o f t h e u s e r ' s c h o i c e . When d e f i n i n g a new f i l e , t h e u s e r p r o v i d e s t h e name and s i z e o f the f i l e t o be d e f i n e d . The system a s s i g n s a b l o c k o f c o n t i g u o u s s e c t o r s and r e c o r d s t h e f i l e name, l o c a t i o n , s i z e and c r e a t i o n d a t e i n t h e u s e r ' s d i s k r e s i d e n t f i l e index. The f i l e may be "opened" a t any subsequent t i m e , which t h e n p l a c e s t h e f i l e ' s s e c t o r bounds i n the r e q u e s t i n g l e v e l ' s PDT (program d e s c r i p tion table). The f i l e space w i t h i n t h e s e bounds may then be used i n any manner t h e u s e r chooses; however, d a t a t r a n s f e r always commences a t t h e b e g i n n i n g o f t h e l o g i c a l d i s k s e c t o r (LDS) s p e c i f i e d (one s e c t o r = 256 words). Each r e q u e s t c o n t a i n s t h e LDS, the c o r e add r e s s f o r d a t a t r a n s f e r and t h e number o f words t o transfer. The a c t u a l s t a r t i n g s e c t o r address i s t h e n d e r i v e d by t h e a d d i t i o n o f the LDS t o t h e lower s e c t o r bound ( c o r e - r e s i d e n t a f t e r f i l e i s "opened"). After i n s u r i n g t h a t t h e u s e r ' s c o r e and f i l e bounds w i l l not be exceeded, t h e o p e r a t i o n i s i n i t i a t e d . To f a c i l i t a t e t h e r a p i d u p d a t i n g o f l a r g e h i s t o grams, o n l y a p o r t i o n o f which can r e s i d e i n c o r e memo r y a t one t i m e , a w r i t e - r e a d f e a t u r e has been p r o v i ded. T h i s p e r m i t s t h e w r i t i n g back on t h e d i s k ( o r RAD) o f a j u s t - u p d a t e d p o r t i o n o f a h i s t o g r a m and the r e a d i n g i n t o the same c o r e a r e a o f t h e a d j a c e n t p o r t i o n of the d i s k - s t o r e d h i s t o g r a m ; a l l i n one d i s k r o t a t i o n . Non-Resident Program E x e c u t i o n . Our r e a l - t i m e c o m p u t a t i o n a l r e q u i r e m e n t s v a r y o v e r a wide range. p u l s e d NMR experiment r e q u i r e s scan a v e r a g i n g a 16K word h i s t o g r a m e v e r y 300 m i l l i s e c o n d s , t a k i n g about m i l l i s e c o n d s p e r update. While t h i s i s t h e h i g h e s t


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usage r e q u i r e d by t h i s e x p e r i m e n t , i t i s needed o c c a sionally. Other experiments r e q u i r e t h e e x e c u t i o n o f a 25K word h i s t o g r a m t r a n s f o r m a t i o n program ( n u c l e a r f i s s i o n d e t e c t o r s ) e v e r y minute, t a k i n g about 5 s e c onds. Other u s e r s r e q u i r e t h i s t y p e o f e x e c u t i o n e v e r y 10 minutes f o r times r a n g i n g from a few seconds to 30 seconds. To s a t i s f y t h i s v a r i e t y o f demand w i t h o u t r e q u i r i n g an i n o r d i n a t e amount o f c o r e memory, t h e o p e r a t i n g system p r o v i d e s f o r the t i m e - s h a r e d e x e c u t i o n o f nonr e s i d e n t programs (not always i n core) i n t h e b a c k ground core a r e a . These programs are d i s k - r e s i d e n t core images o f r e l a t i v e l y l a r g e programs r e q u i r e d i n f r e q u e n t l y and w i t h o u t s e v e r e time c o n s t r a i n t s . Two queues are p r o v i d e d : one w i t h a 1 and t h e o t h e r w i t h a 32 second e x e c u t i o n time l i m i t . These programs are u s u a l l y FORTRAN which are u s e r - w r i t t e n o r from u s e r group l i b r a r i e s . T h i s system f u n c t i o n a l s o makes i t easy f o r the c a s u a l u s e r , who i s c o n v e r s a n t w i t h FORTRAN, t o perform h i s own r e a l - t i m e p r o c e s s i n g . P r i o r t o e x e c u t i o n , a n o n - r e s i d e n t program must be "opened",which c o n s i s t s o f c r e a t i n g and s t o r i n g the c o r e image on a d i s k f i l e and s e t t i n g t h e r e l e v a n t f i l e i n f o r m a t i o n i n t h e u s e r ' s PDT. M u l t i p l e programs may be opened and/or open a t one t i m e . At execution r e q u e s t t i m e , u s i n g the c o r e r e s i d e n t s i z e i n d i c a t i o n , the system w r i t e s a s u f f i c i e n t p o r t i o n o f t h e c u r r e n t lower p r i o r i t y t a s k on t h e d i s k and t h e n reads i n t h e c o r e image n o n - r e s i d e n t program. The t o t a l time r e q u i r e d between t h e r e q u e s t and t h e s t a r t o f nonr e s i d e n t e x e c u t i o n i s about 250 msec, f o r a 15K word program, i f no o t h e r r e q u e s t i s pending; o t h e r w i s e i t must w a i t i t s t u r n i n t h e queue. S e v e r a l o p t i o n s a r e a v a i l a b l e a t e x e c u t i o n t i m e ; c o r e page s i z e i f l a r g e r than the code, a u t o m a t i c "opening" o f u s e r ' s c u r r e n t f o r e g r o u n d f i l e s t o t h e n o n - r e s i d e n t program, queue s e l e c t i o n (1 or 32 s e c . time l i m i t ) and a "save" o p t i o n ( w r i t e program back on d i s k a t e x i t t i m e ) . The "save" o p t i o n a l l o w s s t e p - w i s e e x e c u t i o n . A t e n t r y time, a r e g i s t e r c o n t a i n s t h e address o f t h e r e q u e s t o r ' s c a l l i n g f u n c t i o n parameter t a b l e (which may c o n t a i n an argument l i s t of any l e n g t h ) f a c i l i t a t i n g argument t r a n s f e r . N o n - r e s i d e n t memory w r i t e l o c k s are "ORed" w i t h t h e r e q u e s t i n g l e v e l ' s w r i t e l o c k s , p e r m i t t i n g m o d i f i c a t i o n of the foreground core. C o n c u r r e n t User O p e r a t i o n s . A u s e r ' s program has the o p t i o n o f o v e r l a p p i n g d i f f e r e n t system s e r v i c e s . T h i s i s e f f e c t e d t h r o u g h a " t y p e " o p t i o n i n each c a l l a program makes t o t h e system, s p e c i f y i n g t h e t y p e o f



92

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a c t i o n t h e system s h o u l d t a k e a f t e r i n i t i a t i n g t h e request: 1. I n i t i a t e r e q u e s t and r e t u r n immediately 2. I n i t i a t e r e q u e s t and r e t u r n when r e q u e s t i s completed 3. Return i f o r when t h e p r e v i o u s r e q u e s t o f t h i s k i n d i s completed 4. I n i t i a t e r e q u e s t , c a l l e n d - o f - s e r v i c e and r e t u r n when r e q u e s t f i n i s h e d 5. I n i t i a t e r e q u e s t , r e t u r n immediately and r e t u r n when r e q u e s t f i n i s h e d M u l t i p l e " r e q u e s t f i n i s h e d " i n d i c a t o r s a r e saved i n t h e r e q u e s t o r ' s PDT, w i t h u s e r n o t i f i c a t i o n b e i n g p r o v i d e d on a f i r s t - i n - f i r s t - o u t b a s i s . Using combinations o f t h e above " t y p e s " , a u s e r program may o v e r l a p a number of o p e r a t i o n s t h a t do n o t have t o be completed i n a s p e c i f i c order. F o r example: 1. S t a r t d e v i c e r e a d i n g i n t o next d a t a b u f f e r 2. Move p r e v i o u s d a t a t o magnetic t a p e 3. Write data t o disk 4. Execute a n o n - r e s i d e n t program which g e n e r a t e s display data 5. Computation Having t h e o p t i o n o f b e i n g n o t i f i e d about t h e complet i o n o f t h e v a r i o u s p r o c e s s e s , t h e u s e r program can p r o c e e d as r e q u i r e d . Graphics F a c i l i t i e s . Graphics f a c i l i t i e s c o n s i s t o f a CALCOMP 565 d i g i t a l p l o t t e r and e i g h t T e k t r o n i x 4010 g r a p h i c s u n i t s , t h r e e o f which have 4610 h a r d copy units. T h e i r r e s p e c t i v e FORTRAN c a l l a b l e d r i v e r subr o u t i n e s w r i t e c a l c u l a t e d move-data t o t h e u s e r ' s d i s k plotter-file. A f t e r e x e c u t i n g t h e FORTRAN program i n the b a t c h mode, a r e a l - t i m e CALCOMP u t i l i t y program i s i n i t i a t e d , which r e a d s t h e move-data from t h e d i s k f i l e and w r i t e s t h i s d a t a t o t h e MIOP-coupled CALCOMP. Thus t h e slow moving CALCOMP p l o t t i n g i s performed w h i l e other batch jobs are running. The T e k t r o n i x i n t e r a c t i v e g r a p h i c s u n i t s a r e supp o r t e d w i t h d r i v e r r o u t i n e s t h a t execute a t a f o r e ground l e v e l which i n t u r n makes c a l l s t o t h e u s e r ' s n o n - r e s i d e n t code, r e t u r n t o t h e f o r e g r o u n d l e v e l r e a d s the move d a t a from t h e d i s k and t r a n s m i t s i t t o t h e T e k t r o n i x s c r e e n . Or, t h e f o r e g r o u n d w r i t e s an i n q u i r y on t h e s c r e e n and, a f t e r a subsequent u s e r r e s p o n s e r e t u r n s t h e r e s p o n s e t o t h e n o n - r e s i d e n t program v i a a new execute n o n - r e s i d e n t program r e q u e s t . Thus, nonr e s i d e n t core i s a v a i l a b l e f o r other users during w r i t i n g , r e a d i n g o r w a i t i n g f o r a u s e r t o r e s p o n d t o an i n quiry. P r o v i s i o n i s a l s o made f o r t h e u s e r ' s program t o a s c e r t a i n t h e c o o r d i n a t e s o f thumbwheel c o n t r o l l e d f


6.

DAY

Instrument

c u r s o r c r o s s h a i r s , p r o v i d i n g the u s e r f u r t h e r a c t i o n w i t h h i s program.


93

Control

inter-

Time-Sharing. P r e v i o u s l y c o m p i l e d and s t o r e d (batch mode) FORTRAN IV-H programs can be e x e c u t e d i n a t i m e - s h a r e d mode from any remote keyboard t e r m i n a l (numbering 31). The keyboard t e r m i n a l i s t r e a t e d as the I/O d e v i c e i n p l a c e o f the c a r d r e a d e r and l i n e printer. A c t u a l code e x e c u t i o n t a k e s p l a c e i n b a c k ground c o r e as a n o n - r e s i d e n t program between I/O statements. Programs e x e c u t e d i n such a manner a l s o have a c c e s s t o d i s k and RAD s t o r a g e . In a d d i t i o n t o the u s e r s ' s p e c i a l i z e d programs a l i b r a r y o f c o n v e r s a t i o n a l programs i s a v a i l a b l e . Routines f o r i n t e r a c t i v e g r a p h i c s t e r m i n a l s i n c l u d e : peak r e s o l v i n g , d a t a smoothing, s p e c t r a l d i s p l a y i n g . Interactive routines are a l s o a v a i l a b l e f o r m a n u s c r i p t g e n e r a t i o n u s i n g a t e x t - e d i t i n g package. Open-Shop B a t c h - P r o c e s s i n g . A very important f e a t u r e o f t h e system i s t h e s u p p o r t o f an open-shop b a t c h - p r o c e s s i n g s e r v i c e i n which jobs a r e queued through the c a r d r e a d e r . T h i s t y p e o f queuing p r o v i d e s the c a s u a l u s e r w i t h immediate feedback f o r the r a p i d debugging of h i s programs. B a t c h i s t h e o n l y l e v e l i n the system which has a c c e s s t o t h e " b a t c h p e r i p h e r a l s " ; c a r d r e a d e r , l i n e p r i n t e r , c a r d punch and paper tape reader/punch. The b a t c h l e v e l a l s o has a c c e s s t o d i s k , RAD and magnetic t a p e . A l t h o u g h t h e o n - l i n e u s e r has the o p t i o n o f p e r f o r m i n g e x t e n s i v e a n a l y s i s o f h i s experiment from h i s remote t e r m i n a l , t h e b a t c h l e v e l i s o f t e n u t i l i z e d where l a r g e amounts o f o u t p u t a r e i n v o l v e d and f o r the t r a n s f e r r i n g o f f i l e d a t a onto magn e t i c tape f o r a r c h i v i n g o r t r a n s p o r t t o a n o t h e r computer. The b a t c h l e v e l i s a l s o used e x t e n s i v e l y t o generate and debug code f o r t h e c o n t r o l o f o n - l i n e experiments. The b a t c h l e v e l uses a l l CPU c y c l e s not used by on-going f o r e g r o u n d p r o c e s s e s w h i l e no h i g h e r p r i o r i t y use (e.g. n o n - r e s i d e n t e x e c u t i o n , f o r e g r o u n d l o a d i n g , c o r e image g e n e r a t i o n ) i s r e q u i r e d of the background core a r e a . Under normal daytime system l o a d i n g , t h e f o r e g r o u n d u s e r s r e q u i r e about 10 p e r c e n t o f t h e CPU c y c l e s and the n o n - r e s i d e n t program e x e c u t i o n about another 40 p e r c e n t . Thus, i t appears t o t h e b a t c h u s e r t h a t h i s program i s e x e c u t i n g on a computer w i t h about h a l f t h e speed o f a Sigma 5 computer which was d e d i c a ted to batch-processing. Long-Term Computation. CPU u t i l i z a t i o n seldom exceeds 30 p e r c e n t i n a 24 hour p e r i o d even w i t h heavy r e a l - t i m e and b a t c h usage. The r e m a i n i n g CPU c y c l e s



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are made a v a i l a b l e f o r e x e c u t i n g v e r y l o n g (hours t o weeks) b a t c h - t y p e computations r u n n i n g a t a p r i o r i t y l e v e l below b a t c h p r o c e s s i n g . These j o b s d i f f e r from normal b a t c h i n t h a t t h e y o n l y have a c c e s s t o d i s k and RAD f i l e s , not t h e "batch p e r i p h e r a l s " . Once i n i t i a t e d (from t h e c a r d r e a d e r ) , the job i s r o l l e d i n t o b a c k ground c o r e anytime t h e r e i s s u f f i c i e n t c o r e space and h i g h e r p r i o r i t y usage p e r m i t s . The d a i l y s a v i n g o f f i l e s onto magnetic t a p e a l s o c o p i e s t h e c u r r e n t c o r e image (now s t o r e d on d i s k ) o f t h e l o n g term j o b a l o n g w i t h i t s d i s k and RAD f i l e s . A u t o m a t i c f i l e (and l o n g term) r e s t o r a t i o n a t system b o o t - i n s u p p o r t s e x e c u t i o n s e x t e n d i n g over l o n g p e r i o d s . Incremental Expansion. As more experiments a r e added t o t h e system, one i s concerned w i t h two t y p e s of system e x p a n s i o n ; hardware and s o f t w a r e . The Xerox hardware a r c h i t e c t u r e i s such t h a t e s s e n t i a l l y a l l hardware c a p a b i l i t y i s m o d u l a r l y expandable e x c e p t t h e CPU. For example memory can be expanded i n i n c r e m e n t s of 8K words t o a maximum o f 128K; I/O c h a n n e l s can be added i n groups o f 8 up t o 64 (2 MIOPS) u n t i l a n o t h e r memory p o r t i s added which would t h e n p e r m i t up t o another 64 c h a n n e l s . The a d d i t i o n o f a new i n t e r f a c e d instrument requires the p h y s i c a l connection of i t s a s s o c i a t e d d e v i c e c o n t r o l l e r t o t h e MIOP bus s t r u c t u r e , a one hour j o b , d u r i n g which computer power i s s h u t down. S o f t w a r e e x p a n s i o n need o n l y be c o n c e r n e d w i t h the g e n e r a t i o n of a p p l i c a t i o n s programs f o r each newly i n t e r f a c e d i n s t r u m e n t . The o p e r a t i n g system does n o t r e q u i r e any m o d i f i c a t i o n f o r a new e x p e r i m e n t . At system b o o t - i n time, a l l of t h e r e q u i r e d PDT's a r e g e n e r a t e d from l e v e l parameter cards,one p e r i n t e r f a c e . T h e r e f o r e , a new i n s t r u m e n t r e q u i r e s t h e a d d i t i o n o f o n l y one c a r d t o t h e boot-deck. The a p p l i c a t i o n s programs f o r a new i n s t r u m e n t a r e d e s i g n e d and w r i t t e n i n c l o s e c o n s u l t a t i o n w i t h t h e u s e r s w h i l e t h e new i n t e r f a c e i s b e i n g d e s i g n e d and c o n s t r u c t e d . T o t a l time from c o n c e p t i o n t o o p e r a t i o n runs about 3 t o 6 months. III.

C u r r e n t On-Line

Experiments

The 21 experiments p r e s e n t l y i n t e r f a c e d t o t h e Sigma 5 r e q u i r e w i d e l y d i f f e r i n g t y p e s and amounts o f service. Data t r a n s m i s s i o n r a t e s v a r y from one b y t e per minute t o 100,000 b y t e s p e r second o v e r s h o r t intervals. C o n t r o l r e q u i r e m e n t s v a r y from none, t o computing t h e a n g u l a r c o o r d i n a t e s o f a goniometer from a c r y s t a l l o g r a p h i c o r i e n t a t i o n matrix, to providing p u l s e s e q u e n c i n g f o r r a d i o f r e q u e n c y g e n e r a t o r s . Mass s t o r a g e r e q u i r e m e n t s v a r y from 1000 t o 1,000,000 words.


6. D A Y

Instrument

95

Control

R e a l - t i m e p r o c e s s i n g i n c l u d e s ; scan a v e r a g i n g 16K c h a n n e l s p e c t r a , p e r f o r m i n g mass-energy t r a n s f o r m a t i o n s on c o r r e l a t e d p u l s e - h e i g h t e v e n t s , f a s t f o u r i e r t r a n s f o r m s , l e a s t squares a n a l y s i s , d a t a smoothing and peak f i n d i n g . Table I I i s a l i s t o f the c u r r e n t l y s u p p o r t e d programs w i t h t h e i r a s s o c i a t e d i n s t r u m e n t s .


Quantity 5 2 1 1 1 1 1 1

1 1 1 1 1 1 1 1

Research

Program

Instrument

Type

P a c k a r d 45 p u l s e height analyzer mass s p e c t r o m e t e r s routine chemical analysis (12 i n . 60° sec) B i o m a t i o n 8100 pulsed r a d i o l y s i s transient recorder B i o m a t i o n 802 stopped-flow k i n e t i c s transient recorder V i d a r 520 4 d a t a p r e c i s i o n heat c a p a c i t y a c q u i s i t i o n system time-of-flight c r o s s e d m o l e c u l a r beams detector neutron d i f f r a c crystal structures tometer b i o l o g i c a l system s t r u c t u r e s V a r i a n HR220 super-con p u l s e d NMR Nuclear Chicago very f a s t k i n e t i c s M u l t i s c a l a r (400) Cary 14 s p e c t r o chlorophyll studies photometer Cary 17H s p e c t r o matrix i s o l a t i o n photometer 30 f t . g r a t i n g s p e c t r o m e t e r p l a t e measuring comparator V a r i a n E-9 ESR primary photosynthesis spectrometer V a r i a n E-700 ENDOR p l a n t pigment s t u d i e s spectrometer e n v i r o n m e n t a l r a d i o a c t i v i t y m u l t i - d e t e c t o r (22) c o u n t i n g system e f f u s a t e spectromhigh-temperature chemistry eter fission

and n u c l e a r s p e c t r a

TABLE I I .

Current Interfaced

Instruments

P u l s e d N u c l e a r M a g n e t i c Resonance S p e c t r o s c o p y . T h i s system c o n s i s t s o f a V a r i a n HR220 s u p e r - c o n NMR o p e r a t i n g i n p u l s e d mode f o r p r o d u c i n g f o u r i e r t r a n s form 1h and l 3 c m s p e c t r a (3^£) . Automation i s p r o v i d e d t o c o n t r o l p u l s e s e q u e n c i n g w i t h up t o 10 interval-width pairs: p u l s e - w i d t h s o f 0.5 t o 511 m i c r o s e c o n d i n 0.5 m i c r o s e c o n d s t e p s and i n t e r v a l s o f r


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N

Μ x 2 (where M and Ν range o v e r 0 t o 31) . Data i s d i g i t i z e d w i t h an ADC (8 t o 13 b i t s e l e c t i o n ) and t r a n s m i t t e d d i r e c t l y t o computer memory i n groups o f up t o 16,384 c h a n n e l s w i t h d w e l l times o f as low as 16 y s e c w i t h o u t l o s i n g more than 5 p e r c e n t o f the s c a n s . Data l o s s i s hardware d e t e c t e d and s o f t w a r e compensa t e d ; i n c o m p l e t e scans are d i s c a r d e d . For shorter d w e l l time a h a r d w a r e / s o f t w a r e i n t e r l a c e f e a t u r e has been p r o v i d e d which t a k e s e v e r y N-th (N = 2, 4, 8, 16) d a t a p o i n t from Ν s u c c e s s i v e scans i n an a d v a n c i n g manner, r e q u i r i n g up t o 16 times l o n g e r a c c u m u l a t i o n p e r i o d s , but p e r m i t t i n g a c q u i s i t i o n o f s p e c t r a w i t h d w e l l t i m e s as s h o r t as 1 y s e c . Data i s s c a n - a v e r a g e d i n r e a l - t i m e onto a d i s k - s t o r e d h i s t o g r a m . After a c c u m u l a t i n g the d e s i r e d number o f scans t h e d a t a i s b a s e - l i n e c o r r e c t e d , apodized, f o u r i e r - t r a n s f o r m e d (4K c h a n n e l s r e q u i r e s 3 sec.) and phase c o r r e c t e d . S p e c t r a may be s t o r e d f o r f u t u r e comparison o r a n a l y sis. A " t a u " mode i s p r o v i d e d which w i l l a u t o m a t i c a l l y c o l l e c t and a n a l y z e s p e c t r a at up t o 10 s p e c i f i e d intervals. The s p e c t r o m e t e r i s p r i m a r i l y used f o r n a t u r a l products chemical s t u d i e s , e s p e c i a l l y i n photos y n t h e t i c pigments and i n e l e c t r o n t r a n s p o r t p r o t e i n s . Neutron D i f f r a c t o m e t e r . We have an e x t e n s i v e program i n v e s t i g a t i n g c r y s t a l and m o l e c u l a r s t r u c t u r e s i n t h e 10-300°K t e m p e r a t u r e range on t h e f o l l o w i n g types of m a t e r i a l s : hydrogen bonded such as h y d r a t e d p r o t o n s ; h i g h c o n d u c t i v i t y i n o r g a n i c complexes; b o n d i n g e l e c t r o n d e n s i t y s t u d i e s on i n o r g a n i c and b i o l o g i c a l compounds. Sigma 5 s u p p o r t f o r t h i s e f f o r t i n c l u d e s automation o f a f o u r - c i r c l e n e u t r o n d i f f r a c t o m e t e r (5^6_) , l o c a t e d one m i l e from the computer, which i s c o n t r o l l e d a t any l e v e l o f i n t e r a c t i o n s e l e c t e d by the experimentalist. T h i s i n t e r a c t i o n can be e i t h e r a t the r e a c t o r or i n the u s e r ' s r e m o t e l y l o c a t e d o f f i c e (not a t the r e a c t o r ) . User commands range o v e r t h e following: move c i r c l e "X" t o N-degrees, t a k e a count, scan a d i f f r a c t i o n peak i n a s p e c i f i e d r e g i o n and s t o r e i t s c o o r d i n a t e s , compute a p r e l i m i n a r y o r i e n t a t i o n matrix, determine the l o c a t i o n s of a s e t of r e f l e c t i o n s u s i n g the p r e l i m i n a r y m a t r i x , compute a least-squares adjusted o r i e n t a t i o n matrix u s i n g s e l e c t e d r e f l e c t i o n s , scan r e f l e c t i o n s (up t o 10,000) i n s e l e c t e d r e g i o n s o f r e c i p r o c a l s p a c e . These o p e r a t i o n s may e x t e n d o v e r p e r i o d s from minutes t o weeks (the program i s a u t o m a t i c a l l y r e s t a r t e d a t the a p p r o p r i a t e p o i n t a f t e r system shut-down o r c r a s h ) w i t h o u t human i n t e r v e n t i o n o r t h e y may be suspended, d i s c o n t i n u e d o r t e r m i n a t e d at any t i m e . With t y p i c a l c r y s t a l s i z e s ,



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about 150 t o 400 r e f l e c t i o n s a r e scanned p e r day. P r o v i s i o n i s a l s o made f o r r e a l - t i m e i n t e r a c t i v e e d i t i n g and g r a p h i c d i s p l a y o f d a t a . A n a l y s i s o f s t r u c t u r e s c o n t a i n i n g up t o 50 atoms i n t h e u n i t c e l l a r e g e n e r a l l y run i n b a t c h mode. The a n a l y s i s i n c l u d e s usage o f : the C a n t e r b u r y f o u r i e r program f o r o b t a i n i n g 3 - d i m e n s i o n a l f o u r i e r a n a l y s i s o f i n t e n s i t y ; ORFLS-3 l e a s t squares r o u t i n e w i t h i s o t r o p i c temperature f a c t o r s ; ORFFE-3 f o r o b t a i n i n g atom d i s t a n c e s , a n g l e s and d i h e d r a l a n g l e s . These programs may be run d u r i n g the d a t a a c q u i s i t i o n phase t o a s s i s t i n e s t a b l i s h i n g t h e measurement s t r a t e g y o f a p a r t i c u l a r l y d i f f i c u l t c r y s t a l system. Pulse R a d i o l y s i s . A broad range o f p u l s e r a d i o l y s i s experiments i s c o n d u c t e d a t t h e "LINAC" ( e l e c t r o n a c c e l e r a t o r ) l o c a t e d about 1200 f e e t from t h e computer. They have d e v e l o p e d a new method t o r e c o r d t h e time dependence a b s o r p t i o n o r e m i s s i o n spectrum produced by a single pulse of electrons. The time r e s o l v e d s p e c trum i s produced by an image c o n v e r t e r camera w i t h a s t r e a k c a p a b i l i t y (7_) . The s t r e a k image on t h e phosphor, which i s a two d i m e n s i o n a l a r r a y o f t h e a b s o r p t i o n (or e m i s s i o n ) , i s scanned by a TV camera and s t o r e d on a v i d e o d i s k . Under computer c o n t r o l : t h e v i d e o d i s k image i s scanned one l i n e a t a time; t h e scan i s d i g i t i z e d and s t o r e d as 2000 p o i n t s i n a B i o mation t r a n s i e n t r e c o r d e r ; t h e B i o m a t i o n d a t a i s t h e n t r a n s m i t t e d t o a d i s k f i l e on t h e computer. This p r o c e s s i s r e p e a t e d u n t i l t h e d a t a from about 100 s c a n l i n e s has been s t o r e d . The d a t a from one s c a n l i n e r e p r e s e n t s the l i g h t i n t e n s i t y a t one wavelength as a f u n c t i o n o f t i m e . The e x p e r i m e n t e r may view t h i s d a t a and i n t e r a c t w i t h h i s a n a l y s i s programs v i a a T e k t r o n i x g r a p h i c d i s p l a y u n i t , which has a 4610 h a r d copy u n i t . A f t e r f u r t h e r p r o c e s s i n g , a FORTRAN program i s u s e d t o generate a 3 - d i m e n s i o n a l d i s p l a y o f i n t e n s i t y v e r s u s wavelength and t i m e . A l t e r n a t e programs a r e a v a i l a b l e to g i v e 2 - d i m e n s i o n a l p l o t s o f i n t e n s i t y v e r s u s wavel e n g t h . The e n t i r e p r o c e s s o f o b t a i n i n g t h e d a t a and s t o r i n g i n t h e Sigma 5 t a k e s a matter o f minutes comp a r e d t o days by t h e c o n v e n t i o n a l methods and makes working w i t h h i g h l y r a d i o a c t i v e m a t e r i a l s more f e a s i b l e . In measuring f a s t k i n e t i c s (50 p i c o s e c o n d r i s e t i m e ) which a r e i n i t i a t e d by a p u l s e o f e l e c t r o n s , s i g n a l s a r e o f t e n s m a l l and s i g n a l - t o - n o i s e r a t i o s a r e l i m i t e d by s h o t n o i s e , which means a g r e a t d e a l o f s i g n a l a v e r a g i n g may be n e c e s s a r y . The computer system a l l o w s the s a v i n g o f p a r t i a l a v e r a g e s , so t h a t l o n g a v e r a g i n g t i m e s may be used w i t h o u t f e a r o f l o s i n g e v e r y t h i n g caused by an e x p e r i m e n t a l problem i n the l a s t f i v e


98

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minutes. Good p a r t i a l averages a r e a v e r a g e d and k i n e t i c d a t a are e x t r a c t e d u s i n g n o n - l i n e a r l e a s t squares c u r v e f i t t i n g ; e d i t i n g and d i s p l a y a r e p r o v i d e d on an i n t e r a c t i v e g r a p h i c s t e r m i n a l l o c a t e d a t the experimental s i t e . T h i s scan a v e r a g i n g system i s e f f e c t e d through an i n t e r f a c e d 400 c h a n n e l N u c l e a r Chicago m u l t i - s c a l i n g a n a l y z e r . ENDOR and ESR S p e c t r o s c o p y . A s i g n i f i c a n t p o r t i o n of our e f f o r t s t o c h a r a c t e r i z e p r i m a r y p h o t o s y n t h e s i s i s b e i n g s u p p o r t e d by two i n t e r f a c e d s p i n resonance spectrometers : a V a r i a n E-700 ENDOR ( e l e c t r o n n u c l e a r double resonance) and a V a r i a n E-9 ESR ( e l e c t r o n s p i n resonance) b u f f e r e d by a N i c o l e t 1074 CAT ( s i g n a l a v e r a g e r ) . The uniqueness o f t h e s e spectrome t e r systems d e r i v e s from the l a r g e memory and computat i o n a l speed ( f l o a t i n g p o i n t a r i t h m e t i c ) o f t h e Sigma 5 which a l l o w s the a c q u i s i t i o n and m a n i p u l a t i o n o f l a r g e q u a n t i t i e s o f t h r e e d i m e n s i o n a l d a t a (3-D) v i a two ADC's. A s i n g l e 3-D e x p e r i m e n t may be composed o f up t o 6 40,000 d a t a p o i n t s . F o r example i n the ENDOR mode s i g n a l i n t e n s i t y and r a d i o f r e q u e n c y a r e r e c o r d e d as a f u n c t i o n o f magnetic f i e l d . In t h e ESR mode, t h e t y p i c a l i n t e n s i t y v e r s u s f i e l d spectrum i s r e c o r d e d as a f u n c t i o n o f a t h i r d d i m e n s i o n , such as time f o r k i n e t i c s t u d i e s , or l i g h t i n t e n s i t y f o r p h o t o c h e m i c a l s t u d i e s . Furthermore, s p e c t r o m e t e r o p e r a t i o n i s c o n t r o l l e d by t h e computer; f o r example, i n t h e ENDOR mode t h e comp u t e r s y n t h e s i z e s t h e r a d i o f r e q u e n c y v a l u e , makes d e c i s i o n s about d a t a v a l i d i t y , and t e r m i n a t e s spectrome t e r o p e r a t i o n i f t h e r a d i o f r e q u e n c y power i s i n s u f f i c i e n t . A l l data c a l c u l a t i o n s , i n c l u d i n g s o p h i s t i c a t e d spectrum s i m u l a t i o n s as w e l l as FFT ( f a s t f o u r i e r t r a n s f o r m ) a n a l y s i s i s performed i n r e a l - t i m e by u s e r w r i t t e n FORTRAN programs. These unique f a c i l i t i e s have g r e a t l y s i m p l i f i e d and speeded up t h e u n r a v e l i n g of v a r i o u s fundamental a s p e c t s o f p r i m a r y p h o t o s y n t h e s i s i n our l a b o r a t o r y . Stopped-Flow K i n e t i c s . Using the stopped-flow t e c h n i q u e , k i n e t i c s t u d i e s a r e b e i n g made on systems w i t h s h o r t - l i v e d r e a c t a n t s and p r o d u c t s a t a q u a n t i t a t i v e l e v e l never b e f o r e a c h i e v e d (10,11). Current s t u d i e s c o v e r a v a r i e t y o f a c t i n i d e rêHbx r e a c t i o n s , i n c l u d i n g work w i t h N p ( V I I ) , one o f t h e most p o w e r f u l o x i d a n t s known i n a c i d s o l u t i o n . The a p p a r a t u s c o n s i s t s o f a Durrum model D-110 s t o p p e d - f l o w s p e c t r o p h o t o m e t e r whose o u t p u t i s d i g i t i z e d and s t o r e d i n a B i o m a t i o n 80 2 t r a n s i e n t r e c o r d e r , which i n t u r n i s i n t e r f a c e d t o t h e computer. One t h o u sand d a t a p o i n t s s p a n n i n g a time range o f 0.5 msec, t o


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20 s e c . are c o l l e c t e d per e x p e r i m e n t . R e a l - t i m e s t o r a g e and a n a l y s i s o f the d a t a a l l o w o u t p u t o f the l e a s t s q u a r e s f i t r e s u l t s a t t h e remote s i t e w i t h i n 30 s e c . of the end o f the e x p e r i m e n t . The f a s t t u r n around a l l o w s the e x p e r i m e n t e r t o a d j u s t c o n d i t i o n s c o n t i n u a l l y f o r optimum r e s u l t s . S p e c t r o s c o p i c P l a t e Reading. The s p e c t r o s c o p i c group i s u s i n g a 30 f o o t g r a t i n g s p e c t r o m e t e r t o i n t e r p r e t a c t i n i d e s p e c t r a , each o f which may have up t o 100,000 s p e c t r a l l i n e s . An a u t o m a t i c comparator measures t h e p o s i t i o n o f spectrum l i n e s on an exposed p h o t o g r a p h i c p l a t e by moving i t c o n t i n u o u s l y under a s c a n n i n g s l i t and p h o t o c e l l ; t h e l o c a l b l a c k e n i n g a t s e l e c t e d i n t e r v a l s i s o b t a i n e d by d i g i t a l v o l t m e t e r (DVM) r e a d i n g s o f the p h o t o c e l l c u r r e n t . About 60,000 r e a d i n g s are t a k e n on one scan o f a 250 mm. plate, r e q u i r i n g about 4 m i n u t e s . The d i g i t i z e d (DVM) data i s t r a n s m i t t e d d i r e c t l y t o the computer, s t o r e d and analyzed i n real-time using non-resident execution. The smoothed r e a d i n g s and d e r i v a t i v e s are scanned f o r peaks, and the peak p o s i t i o n s are c o n v e r t e d t o wavel e n g t h by a p o l y n o m i a l f o r m u l a d e r i v e d i n a s e p a r a t e scan o f known s t a n d a r d w a v e l e n g t h s . An i m p o r t a n t c o n v e n i e n c e i s a d i s k f i l e o f s t a n d a r d wavelengths and p o s i t i o n s ; o n l y one p a i r o f knowns i s r e q u i r e d as i n p u t c a l i b r a t i o n , so the system r e q u i r e s much l e s s e f f o r t than manual measurement and a t the same time g i v e s i n c r e a s e d a c c u r a c y (1 i n 1 0 ) . 7

Nuclear P a r t i c l e Detection. A broad area of r e s e a r crTlifirôrt""^^ i s concerned w i t h e l i c i t i n g the d e t a i l s o f the f i s s i o n p r o c e s s . In s t u d y i n g the dynamics o f a m u l t i - n u c l e o n fissioning system, i t i s n e c e s s a r y t o measure t h e changes i n t h e fragment mass and k i n e t i c energy as t h e i n i t i a l e x c i t a t i o n energy, a n g u l a r momentum, and t a r g e t mass and s p i n are a l t e r e d . The i n i t i a l c o n d i t i o n s are most e a s i l y v a r i e d by u s i n g d i r e c t - i n t e r a c t i o n i n d u c e d f i s s i o n r e a c t i o n s such as (d,pf) which a l l o w t h e s i m u l taneous o b s e r v a t i o n o f e x c i t a t i o n e n e r g i e s from below t o 10 MeV above t h e f i s s i o n b a r r i e r . C h a r a c t e r i z i n g t h e s e r e a c t i o n s r e q u i r e s a f i v e parameter e v e n t - b y e v e n t c o r r e l a t i o n o f t h e f i s s i o n fragment e n e r g i e s as w e l l as the l i g h t p a r t i c l e t y p e and e n e r g y . These q u a n t i t i e s a r e c o n v e r t e d t o mass and k i n e t i c energy d i s t r i b u t i o n s i n r e a l - t i m e by u s e r - w r i t t e n programs ( e x e c u t i n g as n o n - r e s i d e n t programs), p e r m i t t i n g s u f f i c i e n t i n t e r a c t i o n between the e x p e r i m e n t a l i s t and a real-time d i s p l a y of h i s transformed data; f a c i l i t a t i n g optimum use o f t h e e x p e r i m e n t a l i s t ' s and a c c e l e r a t o r time.



100

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The computer system s u p p o r t s f i v e d a t a a c q u i s i t i o n areas l o c a t e d i n t h e C h e m i s t r y b u i l d i n g , C y c l o t r o n b u i l d i n g and a t t h e Van De G r a a f f a c c e l e r a t o r i n t h e P h y s i c s b u i l d i n g l o c a t e d about 2,000 f e e t d i s t a n t . Experiments range from s i n g l e p u l s e h e i g h t s p e c t r a ( u s i n g Packard 45 memories and model 160 ADC's), r e c o r d i n g o f e v e n t - t i m e d a t a (at r e s o l u t i o n s o f 40 y s e c . ^ t o m u l t i - p a r t i c l e p u l s e h e i g h t s p e c t r a on up t o s i x ADC's. S i n g l e s , c o r r e l a t e d and t r a n s f o r m e d s p e c t r a a r e g e n e r a t e d i n r e a l - t i m e and a u t o m a t i c a l l y d i s p l a y e d a t a selected interval. An o p t i o n i s a l s o p r o v i d e d f o r s t o r i n g event d a t a p u l s e - h e i g h t s (one o r more ADC's) on magnetic tape f o r subsequent a n a l y s i s i n b a t c h mode or on t o the d i s k f o r r e a l - t i m e d i s p l a y , e d i t i n g and analysis. E v e n t r a t e s o f up t o 10,000 ADC-events/sec. may be p r o c e s s e d . UV, V i s i b l e and I n f r a r e d S p e c t r o s c o p y . Two i n t e r f a c e d Cary s p e c t r o p h o t o m e t e r s (14 and 17H) s u p p o r t t h e D i v i s i o n ' s c h l o r o p h y l l and s u r f a c e s t u d i e s groups. D i g i t a l d a t a from the Cary 14 i s s e n t d i r e c t l y t o t h e computer f o r subsequent d e c o n v o l u t i o n and p l o t t i n g on t h e Calcomp p l o t t e r . On the Cary 17H, t h e scan speed, c h a r t speed and i n t e n s i t y range a r e under computer c o n t r o l (12,13). D i r e c t d i g i t i z a t i o n of the photom u l t i p l i e r o u t p u t has enhanced t h e absorbance a c c u r a c y by a t l e a s t a f a c t o r o f two. Automatic absorbance s c a l e r a n g i n g i s a l s o p r o v i d e d d u r i n g a s p e c t r a l sweep such t h a t t h e u s e f u l absorbance range has been i n c r e a s ed from 0.3 t o 0.4. In a d d i t i o n , t h e problem o f d a t a f i d e l i t y depending on scan speed has been e l i m i n a t e d . R e p e t i t i v e scans w i t h d a t a a v e r a g i n g p r o v i d e s a ready means o f i m p r o v i n g s i g n a l - t o - n o i s e r a t i o s . The d i g i t i zed d a t a are a v a i l a b l e f o r a n a l y s i s by programs which i n c l u d e base l i n e c o r r e c t i o n , G a u s s i a n - L o r e n t z i a n d e c o n v o l u t i o n , peak a r e a measurement, and p l o t t i n g o f t h e o r i g i n a l or program-modified d a t a . Heat C a p a c i t y Measurements. T h i s system i s used f o r t h e p r e c i s e measurement o f t h e heat c a p a c i t i e s o f v a r i o u s c h e m i c a l compounds between 0,1°K and 350°K, a p l a t i n u m r e s i s t a n c e thermometer b e i n g used between 4°K and 350°K and a germanium r e s i s t a n c e thermometer between 0.1°K and 25°K (14,15). Thermometer r e s i s t a n c e s a r e measured w i t h a 6-dTgIt* p o t e n t i o m e t e r whose d i a l p o s i t i o n s a r e a u t o m a t i c a l l y t r a n s m i t t e d t o t h e computer on command. A f i f t e e n t h o r d e r p o l y n o m i a l ( f o r germanium) which c o n v e r t s v o l t a g e t o temperature i s s o l v e d by a n o n - r e s i d e n t program, r e t u r n i n g the time, temperat u r e and temperature d r i f t . A f t e r d r i f t i n g becomes c o n s t a n t , a h e a t i n g c y c l e i s e n t e r e d i n which r e a d i n g s


6. D ^ Y

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o f h e a t e r power and time a r e r e a d a u t o m a t i c a l l y by an i n t e r f a c e d V i d a r 5204D-DAS and t r a s m i t t e d t o t h e computer. F o l l o w i n g h e a t i n g , t h e thermometer c u r r e n t and r e s i s t a n c e s a r e a g a i n f o l l o w e d , u n t i l d r i f t s become constant. The system makes t h e r e c o r d i n g o f t h e d a t a much e a s i e r and more r e l i a b l e and i n a d d i t i o n i t i s much e a s i e r f o r t h e e x p e r i m e n t e r t o d e c i d e when e q u i l i b r i u m has been a t t a i n e d a f t e r t h e h e a t i n g p e r i o d , s o t h a t a n o t h e r h e a t i n g can be i n i t i a t e d . IV.

New

Directions

Our c e n t r a l computer system has s u p p o r t e d p r e s e n t day i n s t r u m e n t a t i o n q u i t e w e l l . However, as t h e a r t of automation advances, e x p e r i m e n t a l i s t s ' l e a r n t o b e t t e r u t i l i z e t h e i r new s o p h i s t i c a t e d t o o l s and new i n s t r u m e n t c a p a b i l i t i e s e v o l v e , i t i s c l e a r t h a t new and more d i f f i c u l t d a t a a c q u i s i t i o n problems w i l l continue t o a r i s e . One o f t h e more demanding problems i s the scan-averaging o f s p e c t r a acquired a t r a t e s a p p r o a c h i n g a m i l l i o n c h a n n e l s p e r second. Another i s more s o p h i s t i c a t e d r e a l - t i m e c o n t r o l o f e x p e r i m e n t s r e q u i r i n g l o g i c d e c i s i o n s (computation) on a m i c r o second time s c a l e . One might t r y t o s o l v e t h e s e p r o b lems by a d d i n g a mini-computer between t h e s e new i n struments and t h e c e n t r a l system. However, one i s then f a c e d w i t h t h e problem o f programming t h e s e i n d i v i d u a l computers ( p r o b a b l y o f d i f f e r e n t manufacture) and d e s i g n i n g an i n t e r f a c e t o t h e c e n t r a l system. I n a d d i t i o n , a mini-computer's r e s p o n s e time i s f a s t e r than a c e n t r a l computer o n l y by v i r t u e o f t h e f a c t t h a t i t t a k e s 4 nanoseconds p e r f o o t (2 way t r a n s m i s s i o n ) f o r d a t a t r a n s m i s s i o n and communication. We a r e i n t e n d i n g t o p r o v i d e h i g h e r speed c a p a b i l i t i e s i n t h e f u t u r e by u s i n g m i c r o p r o c e s s o r s u p p o r t a t the e x p e r i m e n t a l s i t e . Xerox has a System C o n t r o l U n i t which has a wide v a r i e t y o f c o n f i g u r a t i o n s and o p t i o n s including 8 r e g i s t e r s , interrupts, stacks, clocks, r e a d - o n l y and w r i t a b l e memory (16 b i t , 350 and 700 nanosecond) i n i n c r e m e n t s o f IK words, and o p t i o n a l f l o a t i n g p o i n t . We w i l l l o a d t h e s e computers w i t h code from t h e c e n t r a l computer f o r each phase o f i t s d a t a a c q u i s i t i o n e f f o r t , u s i n g them more as a s o p h i s t i c a t e d i n p u t / o u t p u t d e v i c e than as a computer. T h i s w i l l keep t h e programming l o g i c a l l y simple and thus e f f i c i e n t . In a d d i t i o n , t h i s t y p e o f usage w i l l n o t r e q u i r e much memory, thus k e e p i n g t h e c o s t down below t h a t which would be r e q u i r e d by u s i n g a mini-computer.


102


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A N D CHEMISTRY

Summary

The s u c c e s s f u l o p e r a t i o n o f our system o v e r t h e past f i v e years i s a c l e a r demonstration that a c e n t r a l computer, w i t h o u t remote mini-computers, can p r o v i d e very s o p h i s t i c a t e d real-time support without s u f f e r i n g the disadvantages o f u n r e l i a b i l i t y o f t e n experienced i n l a r g e systems. Users never e x p e r i e n c e t h e consequences o f a n o t h e r u s e r ' s e r r a n t program, o n l y t h e i r own. The l e v e l o f system i n t e g r i t y i s such t h a t we t e s t a comp l e t e l y new i n s t r u m e n t c o n t r o l program d u r i n g normal system l o a d i n g , w i t h o u t h a v i n g t o be c o n c e r n e d about i n t e r f e r r i n g w i t h any o t h e r u s e r ' s i n t e r e s t s . Evidence of t h e system's a c c e p t a n c e as u s e r s have been added o v e r t h e y e a r s , i s t h a t we c o n t i n u e t o have 6-8 new u s e r s w a n t i n g t o be i n t e r f a c e d as funds become a v a i l able. The t o t a l c a p i t a l i n v e s t m e n t f o r t h e e n t i r e system i s about $50K p e r experiment, which compares f a v o r a b l y t o the c o s t o f s o p h i s t i c a t e d mini-systems. But, one has much more r e s o u r c e and c a p a b i l i t y t o supp o r t each e x p e r i m e n t : p r o v i d i n g f u l l experiment cont r o l i n a f l e x i b l y i n t e r a c t i v e manner; f u l l y i n t e r a c t i v e g r a p h i c s c a p a b i l i t y w i t h o n - g o i n g and completed e x p e r i m e n t s ; c o m p u t a t i o n a l a b i l i t y f o r complete f i n a l a n a l y s i s o f experiments. APPENDIX Memory Bus S t r u c t u r e . The 960 nanosecond c o r e memory (32 b i t s p l u s p a r i t y ) i s modular; each 16K words has i t s own r e a d - w r i t e and address r e c o g n i t i o n c a p a b i l i t y and may have up t o s i x p o r t s . The CPU and each p r o c e s s o r (MIOP's and CIOP) i s c o n n e c t e d t o i t s own " p o r t b u s " made by j o i n i n g one p o r t from each memory bank. S i m u l t a n e o u s a c c e s s i s a c h i e v e d when r e q u e s t s a r e i n d i f f e r e n t banks and c y c l e s t e a l i n g t a k e s p l a c e when more than one r e q u e s t c o e x i s t s f o r a s i n g l e memory bank. Memory P r o t e c t i o n . A 2 - b i t l o c k and key f e a t u r e p r e v e n t s a u s e r ' s program from m o d i f y i n g u n a s s i g n e d c o r e , w h i l e p e r m i t t i n g t h e e x e c u t i o n o f r e e n t r a n t code. The "key" r e s i d e s i n t h e c u r r e n t PSD (program s t a t u s doubleword), t h e page (512 words) l o c k s a r e s e t i n f a s t memory i n t h e CPU v i a a s i n g l e i n s t r u c t i o n by t h e s c h e d u l e r each time a program l e v e l commences e x e c u tion. Implementation o f t h e p r o t e c t i o n f e a t u r e w i l l t r a p a c o r e - m o d i f y i n s t r u c t i o n b e f o r e e x e c u t i o n and y e t does n o t i n c r e a s e i n s t r u c t i o n e x e c u t i o n t i m e .



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Data Flow. Each MIOP ( m u l t i p l e x o r i n p u t / o u t p u t p r o c e s s o r ) may handle an aggregate d a t a f l o w of 375K memory a c c e s s e s p e r second (one o r f o u r b y t e s ) on up t o 32 c o n c u r r e n t l y a c t i v e d a t a c h a n n e l s ( t y p i c a l l y one per e x p e r i m e n t ) . Only a s i n g l e i n s t r u c t i o n must be executed by t h e CPU t o i n i t i a t e a d a t a t r a n s f e r between any c o r e memory a r e a and a s p e c i f i e d d e v i c e ; a l l subsequent d a t a movement and communication w i t h t h e remote d e v i c e i s h a n d l e d by the MIOP. A t t h e t e r m i n a t i o n o f d a t a t r a n s f e r (up to 65,536 b y t e s ) , the MIOP g e n e r a t e s a single interrupt. Upon r e c o g n i t i o n o f the i n t e r r u p t , the CPU a s c e r t a i n s t h e c h a n n e l number and t h e c h a n n e l end c o n d i t i o n s by e x e c u t i n g a s i n g l e i n s t r u c t i o n . Thus, h i g h speed d a t a t r a n s f e r t o i n d i v i d u a l l y s e l e c t e d c o r e areas ( s p e c i f i e d by each u s e r ' s program) i s comp l e t e l y handled by t h e MIOP, f r e e i n g the CPU t o p e r form u s e f u l computations c o n c u r r e n t l y w i t h d a t a transfers. T e r m i n a l Communications. The CIOP (communications i n p u t / o u t p u t p r o c e s s o r ) h a n d l e s up t o 128 l i n e s of mixed speeds from 110 t o 9600 baud; c u r r e n t l y d r i v i n g 21 t e l e t y p e s , 8 i n t e r a c t i v e g r a p h i c u n i t s and 2 k e y board d i s p l a y s . T h i s p r o c e s s o r works w i t h t h e CPU i n a manner s i m i l a r t o t h a t used w i t h the MIOP. Thus message t r a n s f e r s t a k e p l a c e t o any c o r e memory a r e a w h i l e the CPU i s p e r f o r m i n g computations. Experiment I n t e r f a c e s . Each of t h e r e m o t e l y l o c a t e d o n - l i n e experiments i s i n t e r f a c e d t o a remote controller. The s i m p l e s t c o n t r o l l e r s c o n s i s t o f a one b y t e b u f f e r and a few l o g i c l i n e s . The more complex ones have up t o s i x t e e n b y t e b u f f e r s , computer i n i t i a ted timing c i r c u i t r y to c o n t r o l instrument f u n c t i o n s to a p r e c i s i o n of 0.1 m i c r o s e c o n d and numerous l o g i c l i n e s . For t r a n s m i s s i o n r a t e s up t o 100,000 b y t e s per second a t d i s t a n c e s up t o 1500 f e e t , a remote c o n t r o l l e r i s connected t o a d e v i c e c o n t r o l l e r v i a a b u n d l e o f c o - a x i a l c a b l e (8 b i t wide d a t a p a t h ) . F o r t r a n s m i s s i o n r a t e s o f up t o 4K b y t e s / s e c o n d and a t d i s t a n c e s o f up t o one m i l e , f o u r t w i s t e d p a i r a r e used. The d e v i c e c o n t r o l l e r s were d e s i g n e d by Argonne e n g i n e e r s and a r e connected t o the MIOP bus s t r u c t u r e i n t h e computer main frame, weekly d a t a t r a n s m i s s i o n v a l i d i t y t e s t s on a l l i n t e r f a c e s r u n n i n g c o n c u r r e n t l y f o r about an hour never d e t e c t a t r a n s m i s s i o n f a u l t . About e v e r y e i g h t months one of t h e i n t e r f a c e s f a i l s s o l i d l y because o f component f a i l u r e , which i s r e a d i l y f i x e d w i t h i n a few hours.



104

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NETWORKING AND CHEMISTRY

Core Memory Assignment. With t h e e x c e p t i o n o f system a r e a s , c o r e memory i s a s s i g n e d d y n a m i c a l l y . As u s e r s l o g - o n from t h e i r t e r m i n a l s , s u f f i c i e n t c o r e i s assigned f o r the r e s i d e n t p o r t i o n of t h e i r data a c q u i s i t i o n program, which i n c l u d e s t h e i r own d a t a b u f f e r areas. The programs a r e s t r u c t u r e d i n t o u s e r c o n t r o l l e d o v e r l a y s which a r e t y p i c a l l y w r i t t e n o n t o t h e i r d i s k f i l e and r o l l e d i n t o t h e i r c o r e a r e a as they require. U s i n g t h i s o v e r l a y t e c h n i q u e , t h e average core r e s i d e n c y r e q u i r e d p e r program runs between 2 and 5 pages (page = 5 1 2 w o r d s ) . To p e r f o r m r e a l - t i m e computations u s i n g FORTRAN, t h e f o r e g r o u n d code may c a l l f o r e x e c u t i o n o f a " n o n - r e s i d e n t " program. Foreground c o r e a r e a i s a s s i g n e d from t h e t o p o f c o r e down i n t h e f i r s t a v a i l a b l e b l o c k o f continguous c o r e pages. Background c o r e (batch and system t a s k s ) i s a s s i g n e d from lower c o r e upward. T h i s p e r m i t s t h e maximum b a c k ground c o r e a r e a t o extend on up t o 42,600 words when no r e a l - t i m e t a s k s a r e l o a d e d . W h i l e background c o r e i s v a r i a b l e i n s i z e , t h e u s e r i s always guaranteed an a r e a o f a t l e a s t 15,900 words. R e a l - t i m e j o b l e n g t h s v a r y from minutes t o weeks. On a t y p i c a l day, about 60% o f t h e i n s t r u m e n t s a r e o n - l i n e a t any one time, r e q u i r i n g about 14,400 words o f c o r e . T h i s l e a v e s about 28,200 words o f background c o r e . R e e n t r a n t Code. The Xerox w r i t e - l o c k f e a t u r e , which p e r m i t s t h e e x e c u t i o n o f code anywhere i n memory y e t f o r b i d s t h e m o d i f i c a t i o n o f memory w i t h o u t t h e p r o p e r "key", f a c i l i t a t e s t h e u t i l i z a t i o n o f r e e n t r a n t code t o p e r f o r m many u s e r f u n c t i o n s . R e e n t r a n t code i s d e f i n e d as code t h a t does n o t m o d i f y i t s e l f . About 800 words o f r e e n t r a n t code a r e i n permanent r e s i d e n c e f o r p e r f o r m i n g such f u n c t i o n s as two-way t r a n s l a t i o n o f keyboard I/O and b i n a r y - c o d e d - d e c i m a l c o n v e r s i o n f o r some o f t h e i n t e r f a c e d m u l t i - c h a n n e l a n a l y z e r s . I n a d d i t i o n , t h e r e a r e 12 8 words o f EBCDIC-ASCII c o n v e r sion tables available. Program D e s c r i p t i o n T a b l e s . I n p r o v i d i n g a m u l t i prog raîmnëd~ênvTr^nn^ number ( c u r r e n t l y 41) o f c o n c u r r e n t l y r u n n i n g programs ( u s e r and system), i t was found t h a t a program d e s c r i p t i o n t a b l e (PDT) a s s o c i a t e d w i t h each p r i o r i t y l e v e l was an e f f i c i e n t method o f k e e p i n g t r a c k o f system s e r v i c e r e q u e s t s and i n d i v i d u a l program s t a t u s . B e s i d e s s i m p l i f y i n g p r i o r i t y queuing and l e v e l t e r m i n a t i o n a t e n d - o f - j o b , a PDT s t r u c t u r e a l s o s i m p l i f i e s t h e a d d i t i o n o f a new program l e v e l t o t h e system. PDT g e n e r a t i o n i s c o n t r o l l e d a t system b o o t - i n by one l e v e l - p a r a m e t e r c a r d p e r t e r m i n a l .


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The PDT f o r each p r i o r i t y l e v e l i s 80 words l o n g p l u s two words f o r each I/O command p a i r needed by the l e v e l ( r a n g i n g from 1 t o 16) t o c o n t r o l i t s a s s o c i a t e d device. The t a b l e c o n t e n t a l s o i n c l u d e s ; u s e r ID number, l e v e l s t a t u s , program s t a t u s double words (PSD), memory w r i t e - l o c k image, time r e m a i n i n g , c o r e bounds, d i s k memory f i l e bounds and r e g i s t e r v a l u e s . These t a b l e s a r e s t o r e d i n a w r i t e - p r o t e c t e d a r e a o f c o r e memory. Scheduling. The system s t r u c t u r e / o p e r a t i o n and usage s t r a t e g y have been d e v e l o p e d c o n c u r r e n t l y . Thus a system has e v o l v e d which maximizes t h e system work per u n i t time i n such a manner as t o p r o v i d e t h e r e q u i r e d l e v e l o f r e a l - t i m e i n t e r a c t i o n between t h e u s e r , h i s keyboard and h i s i n s t r u m e n t . However, t h e s p e c i f i c s t r a t e g y used f o r any p a r t i c u l a r a p p l i c a t i o n i s not d i c t a t e d by t h e system as l o n g as programs make r e q u e s t s which conform i n time, c o r e memory, dev i c e o p e r a t i o n and f i l e bounds. A hardware t r a p i s s e t t o d i s a l l o w t h e e x e c u t i o n of p r i v i l e g e d i n s t r u c t i o n s by u s e r code. The b a s i c s c h e d u l i n g a l g o r i t h m runs each t a s k t o c o m p l e t i o n , c o n t i n g e n t upon i t s p r i o r i t y . The schedul e r d e t e r m i n e s what p r i o r i t y l e v e l w i l l e x e c u t e n e x t , t h r o u g h t h e p r o c e s s i n g of a l l I/O i n t e r r u p t s from t h e MIOP, and the maintenance o f s o f t w a r e p r i o r i t y l e v e l s t a t u s u s i n g the PDT's. Once the i d e n t i t y and s t a t u s o f the l e v e l a s s o c i a t e d w i t h an i n t e r r u p t i s d e t e r mined, the s c h e d u l e r compares i t s p r i o r i t y w i t h t h a t o f the l e v e l i n t e r r u p t e d . I f i t i s o f lower p r i o r i t y , t h e i n t e r r u p t e d l e v e l i s resumed. O t h e r w i s e , t h e e x e c u t i o n dependent p o r t i o n (PSD, e x e c u t i o n time and r e g i s t e r s ) o f i t s c u r r e n t s t a t e v e c t o r i s moved t o i t s PDT. Refere n c i n g t h e new ( i n t e r r u p t s i g n a l l e d ) l e v e l ' s PDT, i t s e x e c u t i o n i s i n i t i a t e d by s e t t i n g the memory w r i t e p r o t e c t l o c k s , e x e c u t i o n t i m e , r e g i s t e r s and t h e PSD. Upon r e c e i v i n g an e n d - o f - s e r v i c e (EOS) request from a l e v e l , the s c h e d u l e r r e c o r d s t h i s i n i t s PDT. Then i t scans down t h e p r i o r i t y c h a i n t h r o u g h t h e PDT's u n t i l i t f i n d s another l e v e l t h a t i s " r e a d y - t o - r u n " . S t a t e v e c t o r s are t h e n a d j u s t e d as above t o i n i t i a t e execution. A n e c e s s a r y f e a t u r e i n a multi-programmed system i s t h e p r e v e n t i o n of p r o c e s s i n g l o c k o u t by some h i g h e r p r i o r i t y l e v e l l o o p i n g e n d l e s s l y . A maximum s e r v i c e c y c l e time ( e x e c u t i o n : f o r e g r o u n d = l s e c , n o n - r e s i d e n t = 1 or 32 s e c . , b a t c h and l o n g term=no l i m i t ) and a time r e m a i n i n g v a l u e are s t o r e d i n each PDT. Any time a l e v e l i s e x e c u t i n g , the t i m e - r e m a i n i n g v a l u e i s d e c r e mented by a CPU c l o c k (2000 Hz). But each time a l e v e l


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calls EOS, the maximum service value is moved into the time-remaining PDT location. By breaking processing into logical service cycles, a program can readily perform its function forever, but w i l l be terminated by time-out i f i t malfunctions time-wise.


ABSTRACT A careful study of our laboratory automation needs in 1967 led us to the conclusion that a central compu ter could support all of the real-time needs of a diverse collection of research instruments. A suitable hardware configuration would require an operating sys tem to provide effective protection, fast real-time response and efficient data transfer. An SDS Sigma 5 satisfied all our hardware c r i t e r i a , however i t was necessary to write our own operating system; services include program generation, experiment control real -time analysis, interactive graphics and final analysis. Our system is providing real-time support for 21 concurrently running experiments, including an automa ted neutron diffractometer, a pulsed NMR spectrometer and multi-particle detection systems. It guarantees the protection of each user's interests and dynamically assigns core memory, disk space and 9-track magnetic tape usage. Multiplexor hardware capability allows the transfer of data between a user's device and assigned core area at rates of 100,000 bytes/sec. Real-time histogram generation for a user can proceed at rates of 50,000 points/sec. The facility has been self-running (no computer operator) for five years with a mean time between failures of 10 days and an uptime of 157 hours/ week. Literature Cited 1.

Day, P. and Krejci, Η., Proc. AFIPS FJCC (1968) 33 1187-1196 2. Day, P. and Hines, J., Operating Systems Review (1973) 7 (4) 28-37 3. Scheer, H. and Katz, J. J., Proc. Natl. Acad. S c i . USA (1974) 71 (5) 1626-1629 4. Crespi, H. L., Kostka, A. G. and Smith, U . , Biochem. Biophys. Res. Comm. (1974) 61 (4) 14071414 5. Peterson, S. W., Willett, R. D. and Huston, J. L., J. Chem. Phys. (1973) 59 (1) 453-459 6. Williams, J. Μ., Petersen, J. L., Gerdes, Η. Μ., and Peterson, S. W., Phys. Rev. Lett. (1974) 33 (18) 1079-1081


6. DAY Instrument Control 7. 8. 9. 10. Downloaded by UNIV OF CALIFORNIA SANTA BARBARA on April 3, 2018 | https://pubs.acs.org Publication Date: June 1, 1975 | doi: 10.1021/bk-1975-0019.ch006

11. 12. 13. 14. 15.

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Gordon, S., Schmidt, Κ. H. and Martin, J. E., Rev. Sci. Instrum. (1974) 45 (4) 552-558 Norris, J. R., Uphaus, R. A. and Katz, J. J., Chem. Phys. Lett. (1975) 31 157-161 Norris, J. R., Druyan, M. E. and Katz, J. J., J. Am. Chem. Soc. (1973) 95 1680-1682 Watkins, Κ. O., Sullivan, J. C. and Deutsch, E., Inorg. Chem. (1974) 13 1712 Weschler, C. J., Sullivan, J. C. and Deutsch, E., Inorg. Chem. (1974) 13 2360 Gruen, D. M., Gaudioso, S. L., McBeth, R. L., and Lerner, J. L., J. Chem. Phys. (1974) 60 (1) 89-99 Green, D. W. and Gruen, D. M., J. Chem. Phys. (1974) 60 (5) 1797-1801 Osborne, D. W., Schreiner, F., Flotow, H. E. and Malm, J. G., J. Chem. Phys. (1972) 57 (8) 3401-3408 Osborne, D. W., Flotow, H. E., Fried, S. Μ., and Malm, J. G., J. Chem. Phys. (1974) 61 1463-1468


A Computer Utility for Interactive Instrument Control - ACS Symposium

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