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UBC Theses and Dissertations

A digital data acquisition system for astronomical spectra Isherwood, Barclay Clifford 1971

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A DIGITAL DATA ACQUISITION SYSTEM FOR ASTRONOMICAL SPECTRA by BARCLAY CLIFFORD ISHERWOOD B.Sc., U n i v e r s i t y of B r i t i s h Columbia, 1969 A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE i n the Department of GEOPHYSICS We accept t h i s t h e s i s as conforming to the r e q u i r e d standard THE UNIVERSITY OF BRITISH A p r i l , 1971 COLUMBIA In presenting t h i s thesis in p a r t i a l f u l f i l m e n t of the requirements for an advanced degree at the University of B r i t i s h Columbia, I agree that the Library s h a l l make i t f r e e l y a v a i l a b l e for reference and study. I further agree that permission for extensive copying of t h i s thesis for s c h o l a r l y purposes may be granted by the Head of my Department or by his representatives. It is understood that copying or p u b l i c a t i o n of t h i s thesis f o r f i n a n c i a l gain shall not be allowed without my written permission. Depa rtment The University of B r i t i s h Columbia Vancouver 8, Canada i ABSTRACT C e r t a i n r e s t r i c t i o n s a s s o c i a t e d w i t h conventional photographic techniques have l e d to the use of a low l i g h t l e v e l t e l e v i s i o n tube (isocon tube) as an a l t e r n a t i v e detector f o r astronomical s p e c t r a . An o n - l i n e d i g i t a l data a c q u i s i t i o n system has been developed to process and analyze data from the t e l e v i s i o n camera. The d i g i t a l system c o n s i s t s of a high speed . analog -t o - d i g i t a l c o n v e r t e r , a d i g i t a l computer w i t h magnetic tape t r a n s p o r t and o s c i l l o s c o p e d i s p l a y , and some d i g i t a l c o n t r o l l o g i c . Spectra d i s p l a y e d on the photocathode of the isocon tube are d i g i t i z e d by the A/D converter and s t o r e d on magnetic tape v i a the computer processor. Data a c q u i s i t i o n time f o r one frame of data (1360 samples) i s l e s s than 1.5 seconds. Results obtained w i t h the system i n d i c a t e that i t performs as i n i t i a l l y intended and i s able to r e s o l v e s p e c t r a l f e a t u r e s of the order of 0.1 mm. i i TABLE OF CONTENTS I n t r o d u c t i o n 1 Con t r o l Logic 6 Analog to D i g i t a l Converter 16 The D i g i t a l Computer System 20 Systems Computer Programming 27 Some Results Using the System 29 Summary 41 B i b l i o g r a p h y 42 Appendix A D i g i t a l Logic Symbols 43 Appendix B Systems Program L i s t i n g 44 i i i LIST OF FIGURES Figure 1 Isocon tube arrangement 3 2 System block diagram 5 3 Control Logic 7 4 Timing diagram for control l o g i c 8 5 Timing diagram for beam control pulse 10 6 Programmable decade d i v i d e r 14 7 A/D converter timing 19 8 Systems interface block diagram 23 9 Computer interface f o r A/D converter 25 10 Single lunar spectrum 30 11 Mean lunar spectrum 32 12 Spectrum of Orion 34 13 Spectrum of Arcturus 36 14 Solar spectrum 37 15 Oscilloscope photographs 39 16 Synthetic spectrum 40 i v LIST OF TABLES Table I Standard d e v i a t i o n s and f r a c t i o n a l f o r a mean lunar spectrum e r r o r s 33 V ACKNOWLEDGEMENTS The w r i t e r wishes to acknowledge the a s s i s t a n c e and s t i m u l a t i o n provided by s e v e r a l people i n the Department of Geophysics and Astronomy. S p e c i f i c a l l y , I wish to thank Drs. G. A. H. Walker and T. J . Ul r y c h f o r s u p e r v i s i n g my research and reviewing t h i s t h e s i s and Messrs. P. Michalow and V. Buchholz f o r t h e i r a s s i s t a n c e w i t h the design and c o n s t r u c t i o n of the d i g i t a l data a c q u i s i t i o n system. Mr. J . Blenkinsop and Mr. R. Meldrum provi d e d i n v a l u a b l e a s s i s t a n c e w i t h the computer i n s t a l -l a t i o n and o p e r a t i o n . The f i r s t year of study was supported w i t h a Chevron Standard Graduate Student Fellowship and subsequent work was supported by the N a t i o n a l Research C o u n c i l . 1 INTRODUCTION U n t i l very r e c e n t l y v i r t u a l l y a l l astronomical s p e c t r a have been recorded on photographic p l a t e s . This technique suf-f e r s from a r e l a t i v e l y small dynamic range (15 or 20:1), and a quantum e f f i c i e n c y of l e s s than one percent. A l s o , the response of a photographic p l a t e i s n o n - l i n e a r and c a l i b r a t i o n i s only accurate to about 15 percent. Another disadvantage of t h i s method i s th a t the e x t r a c t i o n of the appropriate astronomical i n f o r m a t i o n i n a form s u i t a b l e f o r a n a l y s i s on a d i g i t a l com-puter i n v o l v e s a considerable amount of tedious work. To circumvent some of these problems a s p e c t r a l data a c q u i s i t i o n system u s i n g t e l e v i s i o n techniques has been developed i n the I n s t i t u t e of Astronomy and Space Science at the U n i v e r s i t y of B r i t i s h Columbia. The p r i n c i p a l components of the system are a low l i g h t l e v e l image isocon t e l e v i s i o n camera, a twelve b i t high speed a n a l o g - t o - d i g i t a l converter w i t h m u l t i p l e x e r and sample-and-hold a m p l i f i e r , a d i g i t a l computer w i t h e i g h t thousand bytes of core memory, and some d i g i t a l c o n t r o l l o g i c . Spectra d i s p l a y e d on the photocathode of the isocon tube are d i g i t i z e d by the A/D converter and sto r e d on magnetic tape v i a the computer processor. The c o n t r o l l o g i c i n t e r c o n n e c t s the t e l e v i s i o n camera, A/D con v e r t e r , and computer. The a c t i o n of the isocon tube has been described by P. D. Nelson (1969). I t has a peak quantum e f f i c i e n c y of about 2 10 percent, and a l i n e a r response over a dynamic range of at l e a s t 200:1. The isocon i s e s p e c i a l l y s u i t e d f o r low l i g h t l e v e l a p p l i c a t i o n s , being able to produce a c l e a r p i c t u r e w i t h i l l u m i n a t i o n s of the order of 10" 6 f o o t - c a n d l e s . A diagram of the isocon tube appears i n Figure 1. L i g h t i n c i d e n t upon the photocathode causes the emission of photo e l e c t r o n s which are a c c e l e r a t e d and focussed by e l e c t r i c and magnetic f i e l d s and s t r i k e the surface of the t a r g e t causing secondary emission. As a r e s u l t , the surface of the t a r g e t charges p o s i t i v e l y and t h i s charge image i s t r a n s f e r r e d to the reverse side of the conducting g l a s s t a r g e t . A beam of e l e c t r o n s produced by the e l e c t r o n gun, and t r a v e l l i n g i n a h e l i c a l path scans the reverse side of the t a r g e t (by magnetic d e f l e c t i o n ) . Since the beam approaches the t a r g e t w i t h very low energy, i t i s only able to land on areas which have been charged to a p o s i t i v e p o t e n t i a l , corresponding to the white parts of the p i c t u r e . A p a r t of the beam which does not land on the t a r g e t r e t u r n s along an almost s t r i g h t path and s t r i k e s the f i r s t dynode. This curre n t i s a m p l i f i e d i n a seven stage dynode c h a i n , then c o l l e c t e d at the anode to produce the video s i g n a l . To enhance low l i g h t l e v e l s i g n a l s , i t i s p o s s i b l e to i n t e g r a t e or accumulate a charge on the t a r g e t f o r an i n t e g r a l number of frames. By b l a n k i n g the reading beam f o r a preset number of frames, i n t e g r a t i o n s i n excess of one hundred seconds are p o s s i b l e . Target read-out l a s t s f o r 0.025 seconds, or one frame time. ISOCON TUBE ARRANGEMENT F O C U S I N G C O I L T A R G E T M E S H D E F L E C T I N G C O I L S P H O T O C A T H O D E V, D Y N O D E C H A I N kW \\ \\\\\ \\ WW \ I A N O D E F I G U R E 1 4 For each observation two spectra are imaged on the photocathode, the sky or background spectrum, and the star (star plus sky) spectrum. There are 680 li n e s i n the scanning raster which i s normal to the spectra. As the reading beam passes over a spectrum, the video signal i s applied to one of two integra-tors which i n turn presents an integrated voltage to the A/D converter. The output of the A/D converter, along with some data check information i s stored in core memory of an Interdata Model IV computer. At the end of a frame of data, some pre-liminary data checks are made on the 1360 samples before they are stored on magnetic tape for future analysis. At the same time the two spectra and the sum of the difference between them are displayed on an oscilloscope monitor. A block diagram of the system appears i n Figure 2. After each frame of read-out, the target must be wiped (neutralized) before the next frame of data i s taken. This i s accomplished by scanning the target with the reading beam on for several frames a f t e r read out. This thesis describes the d i g i t a l instrumentation i n the data a c q u i s i t i o n system. Some of the res u l t s which have been obtained to date using the equipment are also discussed. SYSTEM BLOCK DIAGRAM TELEV IS ION CAMERA A A A INTEGRATER INTEGRATER MPXR A/D CONVERTER CONTROL LOGIC OS I LLOSCOPE DISPLAY TAPE RECORDER c V COMPUTER FIGURE 2 6 CONTROL LOGIC There are two primary f u n c t i o n s f o r the c o n t r o l l o g i c : to provide the r e q u i r e d pulses f o r the c o n t r o l and o p e r a t i o n of the t e l e v i s i o n camera, and to provide the necessary i n t e r -connection and s y n c h r o n i z a t i o n of the d i g i t a l data a c q u i s i t i o n e l e c t r o n i c s . V i r t u a l l y a l l i n t e g r a t e d c i r c u i t s used i n the c o n t r o l l o g i c are of the t r a n s i s t o r - t o - t r a n s i t o r (TTL) l o g i c type. Appendix A gives a d e s c r i p t i o n of the b a s i c l o g i c sym-bols used i n the c o n t r o l l o g i c c i r c u i t diagram of Figure 3. R e f e r r i n g to Figure 3, the l o g i c i s clocked w i t h an o s c i l l a t o r which provides 0 to 5 v o l t pulses at a frequency of 27.2 KHz ( l i n e frequency). The o s c i l l a t o r output i s a p p l i e d d i r e c t l y to the master c o n t r o l u n i t , to produce the l i n e scan waveform. The pulses necessary f o r l i n e r e t r a c e b l a n k i n g are obtained by passing the o s c i l l a t o r output through two monostable m u l t i v i b r a t o r s connected i n tandem. The f i r s t monostable i s used to delay the p u l s e s , w h i l e the second widens the pulses to approximately 10 microseconds. To o b t a i n f i e l d scan p u l s e s , the o s c i l l a t o r output i s counted down by 680, the number of l i n e s per frame, then passed through a monostable m u l t i v i b r a t o r to widen the pulses to one m i l l i s e c o n d before they enter the camera c o n t r o l e l e c t r o n i c s . The decade count down c i r c u i t r y used f o r t h i s and other a p p l i c a t i o n s i n the c o n t r o l l o g i c w i l l be discussed i n more d e t a i l l a t e r . The r e l a t i v e t iming f o r the above l o g i c i s shown i n Figure 4. C O N T R O L L O G I C T I M I N G L I N E P U L S E S L I N E B L A N K I N G T 6 8 0 O U T P U T F I E L D P U L S E L O G I C P U L S E G A T E I G A T E I I A / D C L O C K -SS-•ss-• Si-ll-ss-F I G U R E k 9 As mentioned p r e v i o u s l y , i t i s sometimes d e s i r a b l e to i n t e g r a t e , or b u i l d up a charge on the ta r g e t of the t e l e -v i s i o n tube f o r an i n t e g r a l number of frames. During t a r g e t i n t e g r a t i o n the reading beam must be turned o f f to allo w the charge image to b u i l d up, then turned on f o r the frame of read out, and then f o r seven more frames to wipe ( n e u t r a l i z e ) the ta r g e t before the next i n t e g r a t i o n begins. The beam c o n t r o l pulse i s obtained by counting down the f i e l d frequency (pulses) by the number of frames of i n t e g r a t i o n , then passing these pulses through a s e r i e s of nand gates and f l i p - f l o p s , as shown i n the r i g h t c e n t r a l p o r t i o n of Figure 3 . A d e t a i l e d t i m i n g diagram f o r the d e r i v a t i o n of the beam c o n t r o l pulse appears i n Figure 5 . When the beam c o n t r o l l o g i c i s enabled by s w i t c h i n g S i on, f l i p - f l o p IA i s enabled and f o l l o w s the output of the v a r i a b l e i n t e g r a t i o n count down c i r c u i t . The output of f l i p - f l o p IA along w i t h the i n v e r t e d output of the count down c i r c u i t i s a p p l i e d to gate A to produce a twen t y - f i v e m i l l i s e c o n d p u l s e , the l o g i c p u l s e . As the l o g i c pulse goes h i g h , nand gate C goes hi g h , t u r n i n g the beam pulse on. The t r a i l i n g edge of the l o g i c pulse turns gate C o f f . The three D-type f l i p - f l o p s marked IB, IIA, and IIB coupled w i t h gates B and D act to hold gate C low, hence beam pulse h i g h , f o r seven frames a f t e r read-out. The ei g h t h f i e l d pulse a f t e r read-out turns gate C on which shuts the beam pulse o f f . The beam pulse then remains low f o r a pre-set number of frames of i n t e g r a t i o n , which i s v a r i a b l e from 2 FIGURE 5 11 to 9991, then another c y c l e of read-out and t a r g e t wiping begins. Besides i n i t i a t i n g the beam c o n t r o l p u l s e , the l o g i c pulse i s used to enable the sampling gate which t r i g g e r s the sampling e l e c t r o n i c s . The other input to the sampling gate are p ulses from a dual channel o s c i l l o s c o p e w i t h a v a r i a b l e delay time base. The o s c i l l o s c o p e acts to delay the l i n e scan pulses so that they t r i g g e r the sampling e l e c t r o n i c s as the reading beam passes over the s p e c t r a . This i s accomplished by apply-ing the video s i g n a l to channel one of the o s c i l l o s c o p e and e x t e r n a l l y t r i g g e r i n g the A time base w i t h the l i n e frequency p u l s e s , w h i l e the scope i s operat i n g i n the A i n t e n s i f i e d during B mode. The t r i g g e r pulses can be v i s u a l l y delayed through the o s c i l l o s c o p e using the delayed time base, so that they c o i n c i d e w i t h the p o s i t i o n of the spectrum on the scope and consequently on the photocathode. The pulses to the sample gate are taken from the B gate output of the scope which i s c o i n c i d e n t w i t h the delayed B sweep of the o s c i l l o s c o p e . The output from the sample gate i s put through a mono-s t a b l e m u l t i v i b r a t o r which widens the pulses s u f f i c i e n t l y to t r i g g e r the f i r s t i n t e g r a t o r . The output from t h i s monostable i s a l s o used to t r i g g e r the second i n t e g r a t o r a f t e r the pulses have been widened and delayed s u f f i c i e n t l y u sing two more mono-s t a b l e s . Gate 1, the pulse which f i r e s the f i r s t i n t e g r a t o r , i s a l s o used to switch the m u l t i p l e x e r and cl o c k the A/D con-v e r t e r . This i s done by passing the gate 1 pulses through two 12 one shots connected i n p a r a l l e l . As i n d i c a t e d i n Figure 3, the f i r s t monostable delays the pulses f o r 2.5 microseconds, while the second one has a delay of 14 microseconds. The "0" outputs of these two one shots are a p p l i e d to a nand gate to y i e l d s uccessive pulse p a i r s w i t h approximately 10 microsecond s e p a r a t i o n which are fed to the m u l t i p l e x e r and A/D converter. A t h i r d f u n c t i o n of the l o g i c pulse i s to generate the computer block pulse using f l i p - f l o p IVA. The computer block pulse which i s the same width as the l o g i c pulse (25 m i l l i s e c o n d s ) i s used to open and c l o s e the computer i n t e r f a c e . When the block pulse i s o f f (low) a l l data t r a n s f e r s to the com-puter are i n h i b i t e d . The d i g i t i z e d data i s clocked i n t o com-puter memory using the data a v a i l a b l e pulse which i s generated by the A/D converter at the completion of each d i g i t i z a t i o n . For each d i g i t i z a t i o n the computer r e c e i v e s f i f t e e n data b i t s . Twelve b i t s , b i t s 0 through 11, are output from the A/D c o n v e r t e r , while the other three are data check b i t s . B i t 12 i s the address b i t from the m u l t i p l e x e r and i s used to check that the m u l t i p l e x e r i s s w i t c h i n g from channel to channel. B i t 13, the quarter wave p l a t e b i t , which i s de r i v e d from the l o g i c pulse i s -used to check i f the computer misses a frame of data. B i t 14 i s the output of a fourteen b i t p a r i t y t r e e which generates odd p a r i t y f o r the above fourteen data b i t s . The p a r i t y b i t i s used to check each data t r a n s f e r f o r any malfunc-t i o n i n the data l i n e s between the A/D converter and the computer. Variable Divide-By C i r c u i t s The d i g i t a l counters used i n the c o n t r o l l o g i c f o r f i e l d scan and beam b l a n k i n g c o n t r o l are programmable decade d i v i d e - b y c i r c u i t s . The p r i n c i p a l component of each decade i s a s h i f t r e g i s t e r which i s composed of four c l o c k e d master-slave f l i p - f l o p s w i t h D i n p u t s . The D input of every stage can be switched between two l o g i c a l sources of the P a r a l l e l Enable (PE) i n p u t . When the PE input i s low, the D inputs of the four stages (Q 0, Q i , Q2, and Q 3) are l o g i c a l l y connected to the p a r a l -l e l inputs ( P 0 , P i , P2, and P 3 ) . When the PE input i s h i g h , the D inputs of stages Q i , Q2, and Q3 are connected to the outputs of Q0, Q i , and Q2 r e s p e c t i v e l y , thus forming a f o u r - b i t s h i f t r e g i s t e r . Each counter decade c o n s i s t s of one s h i f t r e g i s t e r and seven nand gates interconnected to y i e l d a programmable counter which i s v a r i a b l e from one to nine. The c i r c u i t d i a -gram i s shown i n Figure 6A. Any number of these decade program-mable d i v i d e r stages may be connected together to produce a d i v i d e r of any value. In t h i s case the value of each d i g i t of the d i v i d e r depends only on the four i n p u t s , P 0, P i , P2 and P 3 of that decade. Both the d i v i d e by X and the d i v i d e by 680 c i r c u i t i n the c o n t r o l l o g i c use three decades connected together as shown i n Figure 6B. The inputs to the d i v i d e by 680 c i r c u i t P R O G R A M A B L E D E C A D E D IV IDER B O R R O W I N P U T L O A D E N A B L E I N P U T -P R O G R A M I N P U T P E P P P P C S H I F T KP R E G I S T E R Q n Qi Q ? Q 3 B O R R O W T O N E X T S T A G E L O A D E N A B L E O U T P U T F I G U R E 6 A C L O C K I N L l O N E O N E O N E D E C A D E r> D E C A D E D E C A D E C L O C K O U T F I G U R E 6 B 15 are hard wired to f i x the count at 680 while the inputs to the i n t e g r a t i o n counter are s e l e c t a b l e to produce a counter which i s v a r i a b l e from 2 to 991. An a d d i t i o n a l times ten c i r c u i t i s a v a i l a b l e to increase the count to 9,9910. 16 ANALOG-TO-DIGITAL CONVERTER The a n a l o g - t o - d i g i t a l converter used i n the system i s a Biomation Model 712 converter manufactured by Data Labo-r a t o r i e s L t d . This device was chosen as the most s u i t a b l e d i g i -t i z e r f o r s e v e r a l reasons. The A/D converter chosen f o r the system would have to process 1360 samples i n one frame time or 25 m i l l i s e c o n d s . This t r a n s l a t e s to a minimum conversion r a t e of 54.4 k i l o c y c l e s . The Biomation A/D converter i s w e l l above t h i s minimum, being capable of 100,000 conversions per second f o r twelve b i t d i g i t i z a t i o n s . A l s o , the Biomation converter has a l a r g e o p e r a t i n g temperature range (0 to 60°C), which i s important f o r astronomical work, and was about one h a l f of the cost of most comparable A/D systems. A b r i e f d e s c r i p t i o n of the o p e r a t i o n of the A/D converter i s given below. The conversion technique used i n the A/D converter i s the b i n a r y approximation method. Currents of b i n a r y weighted p r o p o r t i o n s are s u c c e s s i v e l y switched i n t o a current summing network; the input v o l t a g e to be d i g i t i z e d i s converted to an equ i v a l e n t c u r r e n t and i s compared wi t h the weighting network c u r r e n t . The weighting c u r r e n t s are switched i n sequence, s t a r t i n g w i t h the most s i g n i f i c a n t v alue; each time a new cur-rent i s switched i n , a comparison i s made and depending on the r e s u l t , that c u r r e n t i s l e f t i n or removed. The sample-and-hold a m p l i f i e r used i n the A/D system has an e f f e c t i v e aperture time (the minimum time p e r i o d over 17 which the sample-and-hold e l e c t r o n i c s must look at the input to o b t a i n a sample) of l e s s than 20 nanoseconds. The sampling e r r o r i n t r o d u c e d due to a f i n i t e aperture time of 20 nanoseconds i s very s m a l l , about 0.1% f o r an input s i g n a l frequency of 8 k i l o c y c l e s . The A/D converter has been modified by the a d d i t i o n of a dual channel m u l t i p l e x e r . The necessary e l e c t r o n i c c i r -c u i t r y f o r t h i s m o d i f i c a t i o n was provided by the manufacturer and i n s t a l l e d i n the A/D converter by the w r i t e r . The m u l t i -p l e x e r s i t s i n f r o n t of the sample-and-hold c i r c u i t r y so that channel s w i t c h i n g and data s e t t l i n g may be accomplished during a previous conversion p e r i o d , thus m a i n t a i n i n g the high through-put r a t e of the A/D converter. The m u l t i p l e x e r r e q u i r e s 4.5 microseconds to switch channels and s e t t l e to 0.025 percent of maximum, whereas the A/D converter r e q u i r e s a minimum of 5.6 microseconds f o r each d i g i t i z a t i o n so that the analog data should be w e l l s e t t l e d on the l i n e s before i t i s r e q u i r e d by the sample-and-hold a m p l i f i e r . The d i g i t i z e d output from the A/D converter i s i n 2's complement n o t a t i o n and i s b u f f e r e d through a s e r i e s of f l i p - f l o p s so that each d i g i t i z a t i o n i s a v a i l a b l e at the out-put u n t i l the subsequent conversion i s complete. As mentioned p r e v i o u s l y , the A/D converter and mul-t i p l e x e r are c o n t r o l l e d by pulses d e r i v e d from the system c o n t r o l l o g i c . The A/D converter generates two output c o n t r o l 18 lines; Data available •which is at logic one at the end of each conversion, and Busy which is at logic one for the duration of each conversion and at logic zero otherwise. Figure 7 shows the input and output control pulses for the A/D converter on the time scale used in the present system. CONVERT (CLOCK) n/Jisec A/D CONVERTER TIMING DIAGRAM ZQMsec SAMPLE ( INTERNAL) t>/isec £ftsec BUSY 10/iSCC DATA AVAIL , MPXR. STEP MPXR. ADDRESS DATA IN BUFFER Data, of first con/ert Data of next conversion FIGURE 7 20 THE DIGITAL COMPUTER SYSTEM The d i g i t a l computer system c o n s i s t s of an In t e r d a t a Model IV processor w i t h 8K bytes of memory, a nine t r a c k syn-chronous tape t r a n s p o r t , and a cathode ray o s c i l l o s c o p e . The processor accepts d i g i t i z e d data from the A/D con v e r t e r , performs some p r e l i m i n a r y data checks on the data, and w r i t e s i t on to magnetic tape. The o s c i l l o s c o p e i s used to monitor the contents of core memory at the end of each frame of data. The I n t e r d a t a Model IV was chosen over comparable processors f o r s e v e r a l reasons. The Model IV has s i x t e e n 16-b i t general purpose hardware r e g i s t e r s , twelve more than other processors considered. These r e g i s t e r s are u s e f u l as accumu-l a t o r s i n f i x e d p o i n t a r i t h m e t i c , or as index r e g i s t e r s i n addressing and indexing o p e r a t i o n s . An advantage i n having a la r g e number of hardware r e g i s t e r s i s that any two of these r e g i s t e r s may be used f o r r e g i s t e r - t o - r e g i s t e r i n s t r u c t i o n s , thus e l i m i n a t i n g redundant load and stor e operations w i t h core memory. Another advantage of the In t e r d a t a system i s that a l l core memory i s d i r e c t l y addressable w i t h the primary i n s t r u c t i o n word; no paging or i n d i r e c t addressing such as that r e q u i r e d f o r most small computers i s used. Further, the I n t e r d a t a system provides a comprehensive assembly language i n s t r u c t i o n set wi t h a high degree of i n d i v i d u a l programming f l e x i b i l i t y . The set inc l u d e s r e l a t i v e l y f a s t byte processing i n s t r u c t i o n s , s i n g l e i n s t r u c t i o n s f o r loop c o n t r o l which increment, t e s t and branch 21 on i n d e x i n g v a l u e s , as w e l l as i n s t r u c t i o n s that t e s t the c o n d i t i o n code of the program st a t u s word and branch to any l o c a t i o n i n memory. The I n t e r d a t a processor i s i n t e r f a c e d to a model 6X60 synchronous tape t r a n s p o r t manufactured by P e r i p h e r a l Equipment Corpora t i o n . The tape d r i v e has nine read/write heads, a tape packing d e n s i t y of 800 b i t s per i n c h , and a con-tinuous tape read/write speed of 25 inches per second. A nine t r a c k tape d r i v e was chosen to permit the most e f f i c i e n t packing of 8 - b i t bytes of data from the I n t e r d a t a processor. The n i n t h t r a c k on the magnetic tape i s used f o r v e r t i c a l p a r i t y . A tape packing d e n s i t y of 800 b i t s per inch was chosen over 556 b i t s per i n c h to ensure a f a s t data t r a n s f e r r a t e (20,000 bytes per second at a tape speed of 25 inches per second). The tape t r a n s -p o r t c o n t r o l l e r i s equipped w i t h a c y c l i c redundancy check cha r a c t e r generator. This generator provides s p e c i a l charac-t e r s to make a l l tapes w r i t t e n w i t h the P e r i p h e r a l Equipment d r i v e f u l l y I.B.M. compatible. The o s c i l l o s c o p e used to monitor the contents of the computer core memory i s a model RM503 instrument manufactured by T e k t r o n i x Inc. The computer i n t e r f a c e f o r the o s c i l l o s c o p e i n c l u d e s a ten b i t d i g i t a l - t o - a n a l o g converter which converts the contents of core memory f o r d i s p l a y on the o s c i l l o s c o p e . The i n t e r f a c e a l s o provides the t r i g g e r c o n t r o l f o r the scope. 22 The RM503 does not have a storage f a c i l i t y so that the computer must c o n t i n u a l l y recharge the d i s p l a y on the cathode ray tube. A/D Converter Interface There are three separate methods by which the I n t e r -data processor communicates wi t h p e r i p h e r a l devices or systems. They are the M u l t i p l e x e r Channel, the S e l e c t o r Channel, or the Standard Memory Bus I n t e r f a c e (S.M.B.I.). Each of the three methods communicates v i a a bus w i t h i n d i v i d u a l device c o n t r o l l e r s , which provide data and c o n t r o l . i n t e r f a c e to the i n d i v i d u a l de-v i c e s . The I n t e r d a t a system being used f o r the present a p p l i -c a t i o n makes use of both the m u l t i p l e x e r channel and the standard memory bus i n t e r f a c e . The m u l t i p l e x e r bus, a byte o r i e n t e d I/O system handles data t r a n s f e r s f o r the tape t r a n s p o r t and the o s c i l l o s c o p e d i s p l a y , while the A/D converter i s i n t e r f a c e d to the computer through the "standard memory bus i n t e r f a c e . A block diagram of the systems i n t e r f a c e appears i n Figure 8. A d e t a i l e d d i s c u s s i o n of the i n t e r f a c e c o n t r o l l e r s f o r the tape t r a n s p o r t and o s c i l l o s c o p e i s beyond the scope of t h i s t h e s i s , but may be found i n standard I n t e r d a t a p u b l i c a t i o n s . The Standard Memory Bus I n t e r f a c e was chosen as the most s u i t a b l e access route f o r the data from the A/D converter because of i t s high data t r a n s f e r r a t e (100 k i l o c y c l e s ) and i t s a b i l i t y to t r a n s f e r s i x t e e n data b i t s i n p a r a l l e l . The S.M.B.I. SYSTEMS INTERFACE BLOCK DIAGRAM C O R E M E M O R Y H I G H S P E E D M E M O R Y B U S P R O C E S S O R M U L T I P L E X E R C H A N N E L 7^ Z. S E L E C T O R C H A N N E L 7 ^ M U L T I P L E X E R B U S x S C O P E C O N T R O L L E D S E L E C T O R B U S 0 T A P E M T C O N R O L l E R S C O P E T A P E D R I V E S T A N D A R D M E M O R Y B U S I N T E R F A C E A / D C O N V E R T E R D E V I C E C O N T R O L L E R A / D C O N V E R T E R F I G U R E 8 24 i s capable of t r a n s f e r r i n g one halfword (16 b i t s ) of data i n l e s s than one microsecond. The device c o n t r o l l e r to accompany the S.M.B.I. was designed and b u i l t by I n t e r d a t a according to spe-c i f i c a t i o n s . Through the c o n t r o l l e r the d i g i t i z e d data i s t r a n s f e r r e d d i r e c t l y to memory where each data word occupies one halfword of core memory. As discussed p r e v i o u s l y , twelve of the s i x t e e n b i t s c o n t a i n A/D converter data, three more con-t a i n data check i n f o r m a t i o n , and one i s l e f t unused. The i n -t e r f a c e i s capable of t r a n s f e r r i n g up to 125,000 data words per second. Data are t r a n s f e r r e d to memory a block (frame) at a time; a s s o c i a t e d w i t h each block are s t a r t and end memory address l i m i t s which are set i n t o the i n t e r f a c e by the programming to determine where i n core the data w i l l go. Once the address l i m i t s are set and the i n t e r f a c e i s enabled, i t w i l l accept data from the A/D converter and store them i n memory independent of the processor. At the end of a frame of data, the i n t e r f a c e n o t i f i e s the processor by an i n t e r r u p t or stat u s c o n d i t i o n . A block diagram of the i n t e r f a c e i s shown i n Figure 9. As mentioned p r e v i o u s l y , the c o n t r o l pulses f o r the i n t e r f a c e are obtained from the system c o n t r o l l o g i c . The block pulse must be high before the i n t e r f a c e w i l l accept data from the A/D converter, while the data are clocked through the i n t e r -face by the Data A v a i l a b l e pulses from the A/D converter. I f the A/D converter t r i e s to send data to the i n t e r f a c e while i t i s i n the c l o s e d mode (block pulse low) a stat u s ( e r r o r ) b i t i s C O M P U T E R I N T E R F A C E B L O C K D I A G R A M M E M O R Y I / O M P X B U S 0 < M E M O R Y B U S I / O B U S C O M M U N I C A T I O N S L O G I C C O N T R O L L O G I C I N T . G E N S T A T U S G A T E S 7f M E M O R Y C O M M U N I C A T I O N S L O G I C M E M A D D R S T A R T A D D R E S S » ( I N C R E M E N T I N G ) R E G I S T E R E N D A D D R E S S R E G I S T E R C O M P A R E L O G I C I N C M E M O R Y A D D R E S S A D O N M E M D A T A M E M O R Y C O N T R O L L O G I C A / D C O N V E R T E R F I G U R E 9 26 set i n the i n t e r f a c e . S i m i l a r l y , i f any data pulses from the A/D converter a f t e r the t o t a l b l o c k , as p r e s c r i b e d by the s t a r t and end addresses have been t r a n s f e r r e d , another sta t u s ( e r r o r ) b i t i s s e t . At the end of each block t r a n s f e r the c o n d i t i o n of these b i t s i s checked and a record of any e r r o r s i s kept i n the memory, of the computer. 27 COMPUTER PROGRAMMING The computer programming f o r the data processing and a n a l y s i s was w r i t t e n i n I n t e r d a t a assembly i n cooperation w i t h Dr. J . R. Auman. The program takes up approximately 1300 bytes of core memory. There i s an a d d i t i o n a l requirement of 6600 bytes of memory f o r b u f f e r storage of incoming d i g i t a l data and magnetic tape read/write data checks. When the system i s i n o p e r a t i o n , the operator may request the computer to perform any one of s e v e r a l f u n c t i o n s by p r e s s i n g one of twelve switches on the d i s p l a y panel of the computer. These options i n c l u d e whether or not the incoming data i s to be w r i t t e n on magnetic tape, which channels of the incoming data are to be d i s p l a y e d on the o s c i l -loscope monitor, and which p a r t i c u l a r form of data enhancement i s to be a p p l i e d to the data. B a s i c a l l y the computer program i n s t r u c t s the computer to perform the f o l l o w i n g f u n c t i o n s i n about the order given. The computer accepts a block of data (1360 halfwords) from the A/D converter and checks i t f o r p a r i t y e r r o r s . At the same time, i t checks the quarter wave p l a t e b i t ( b i t 12) and the A/D converter address b i t ( b i t 13) to make sure that they have switched between each block and each halfword of data respec-t i v e l y . A count of quarter wave p l a t e , p a r i t y , and address e r r o r s are kept i n separate f i x e d p o i n t r e g i s t e r s . The program then computes the d i f f e r e n c e between the s i g n a l and background values f o r the 680 data p o i n t s i n the frame and adds t h i s r e s u l t to a 28 b u f f e r area which c o n t a i n s the sum of the d i f f e r e n c e f o r a l l frames of a s i n g l e spectrum. Next the p r o c e s s o r outputs the data (2720 bytes) on to magnetic tape, backspaces the tape, reads the data back and compares t h i s to the o r i g i n a l m a t e r i a l s t i l l h e l d i n core memory. I f a tape w r i t e e r r o r i s d e t e c t e d , the o r i g i n a l data i s r e - w r i t t e n on to tape and checked a g a i n . A f t e r the frame of data has been w r i t t e n , the d i s p l a y p a n e l c o n t r o l switches are checked f o r any changes i n program execu-t i o n . F i n a l l y the computer d i s p l a y s the r e s u l t s of the most r e c e n t d i g i t i z a t i o n on the o s c i l l o s c o p e monitor. The computer co n t i n u e s to r e f r e s h the o s c i l l o s c o p e d i s p l a y u n t i l i t i s n o t i f i e d by the A/D c o n v e r t e r t h a t more data i s a v a i l a b l e f o r p r o c e s s i n g . A l i s t i n g o f the program i s g i v e n i n Appendix B. 29 SOME RESULTS USING THE SYSTEM The f i r s t t e s t run of the equipment took place at the coode focus of the f o r t y - e i g h t inch telescope at the Dominion A s t r o p h y s i c a l Observatory i n V i c t o r i a , B.C. during October 1970. The primary f u n c t i o n of t h i s experiment was to p i n - p o i n t any weaknesses-in the i n s t r u m e n t a t i o n . Several minor f a u l t s i n the A/D converter and computer c o n t r o l l o g i c were discovered and c o r r e c t e d at t h i s time. During mid-December 1970, the system was used by Drs. Walker and Auman of the U n i v e r s i t y of B.C. on the McMath So l a r Telescope at the K i t t Peak N a t i o n a l Observatory near Tucson, A r i z o n a . In g e n e r a l , the equipment performed up to expectations and a l a r g e amount of good s p e c t r a l data was obtained. For each observation about f i f t y frames of s p e c t r a and f i f t y frames of dark current were processed and s t o r e d on magnetic tape. The time r e q u i r e d to acquire and process one frame of data i s approximately 1.5 seconds. The data were l a t e r analyzed and p l o t t e d using the I.B.M. system 360/65 at the Uni-v e r s i t y of B.C. Figures 10 through 14 show some of the p l o t t e d p r o f i l e s . Figure 10 i s a s i n g l e l i n e spectrum of the moon i n o the wavelength re g i o n of 5250 A. The moon was chosen as the f i r s t o b j e c t f o r o b s e r v a t i o n f o r s e v e r a l reasons. Being a r e l a t i v e l y b r i g h t o b j e c t i n the n i g h t sky, i t would be a good source f o r p r e l i m i n a r y adjustments of the t e l e v i s i o n camera and a s s o c i a t e d e l e c t r o n i c s i n the system. Secondly, the moon 31 provided an extended source of known spectrum f o r determining the r e s o l u t i o n of the t e l e v i s i o n camera. A l s o , i t was hoped to look at the same wavelength re g i o n i n the s o l a r spectrum l a t e r i n the observing program, and p o s s i b l y compare the two sp e c t r a f o r s c a t t e r i n g e f f e c t s caused by the lunar s u r f a c e . Unfor-t u n a t e l y i t was d i f f i c u l t to o b t a i n a very good p r o f i l e from the sun due to s c a t t e r e d l i g h t e n t e r i n g the camera and lens system and a d e t a i l e d comparison of the two s p e c t r a could not be made. The s p e c t r a l f e a t u r e s at about 115 and 530 samples are f i d u c i a l marks on the photocathode. The mean p r o f i l e of one hundred frames of the lunar o spectrum at 5250 A i s shown i n Figure 11. As one would expect, the mean p r o f i l e contains c o n s i d e r a b l y l e s s noise than the s i n g l e spectrum of Figure 10. Moreover the i n d i v i d u a l f e a t u r e s of the p r o f i l e appear to be sharper on the mean spectrum than on the s i n g l e spectrum. From the 650 mean sample values used to p l o t the mean spectrum, the standard d e v i a t i o n , a, and the f r a c t i o n a l e r r o r were c a l c u l a t e d . The l a r g e s t value obtained f o r o was 0.033 w i t h an a s s o c i a t e d f r a c t i o n a l e r r o r of 0.056. This r e s u l t i n d i c a t e s that measurements taken w i t h the data a c q u i s i t i o n system should be very p r e c i s e indeed. A l i s t i n g of the c a l -culated'values f o r the standard d e v i a t i o n and f r a c t i o n a l e r r o r f o r sample p o i n t s one t o . f i f t y - o n e appears i n Table 1. Figure 12 shows a l i n e p r o f i l e from the Orion Nebula o i n the re g i o n of 4950 A. The strong emission l i n e appearing 33 TABLE I -- STANDARD DEVIATIONS AND FRACTIONAL ERRORS FOR A MEAN LUNAR SPECTRUM MEAN SIGMA FRAC. ERROR 0.02 1158 0 .004739 0 .223993 1 0.0 18813 0.004745 0.252245 2 0.021856 0.004283 0. 195943 3 0.019062 0.004447 0 .233266 4 0.022954 0.004672 0.203540 5 0.024651 0.004826 0.195756 6 0.021058 0.004454 0.211495 7 0.023503 0.0 04409 0.187610 8 0.020359 0.004413 0.216736 9 0.020409 0 .004096 0.200673 10 0.024352 0.004621 0.189744 11 0.024901 0.004759 0 . 191122 12 0.019311 0.004188 0.216879 13 0.027396 0.004904 0 . 179003 14 0.034581 0 .005025 0.145319 15 0.031487 0.004945 0.157054 16 0.033434 0 .005662 0.169339 17 0.031338 0.005019 0.160 160 18 0.0 32435 0 .005200 0.160332 19 0.0 32236 0.005131 0 . 159167 20 0.027645 0.005066 0. 183253 21 0.030589 0.005159 0.168652 22 0.030789 0 .005400 0 . 175390 23 0.029841 0 .004840 0 .162196 24 0.034182 0.004863 0 . 142256 25 0.037526 0 . 005025 0 . 133896 26 0.033084 0.004587 0.138644 27 0.0412 18 0.004731 0.114781 28 0.048803 0.005535 0.113424 29 0.080490 0.006244 0.077579 30 0.101200 0 .0.0 69 81 0.068981 31 0.160 183 0 .008462 0 .052825 32 0.238874 0.009249 0 .038720 33 0.350202 0.009253 0.026423 34 0.468670 0.008874 0 .0 18934 35 0.574410 0 .0 10705 0.018636 36 0.699664 0.0 10381 0.0 14838 37 0.797758 0.0 11267 0.0 14124 38 0.880602 0 .009812 0.011142 39 0.939586 0.009614 0.0 10232 40 0.993869 0.010911 0 . 0 10978 41 1.026817 0.010931 0.010645 42 1.095822 0.009965 0.009093 43 1.129158 0 .009713 0 .00 8602 44 1.147118 0.010034 0.008747 45 1.175373 0.011437 0.009731 46 1.196921 0 .0 10709 0.008947 47 1.224874 0 .0 10965 0 .008952 48 1.259550 0.011125 0 .008833 49 1.282561 0.011477 0.008949 50 1.331257 0.010082 0.007573 51 oo SPECTRUM OF ORION CD. to 9-i o . o 0.0 10.0 20.0 30.0 40.0 50.0 60.0 70 FIGURE 12 35 on the p r o f i l e i s the [0 I I I ] l i n e at 4958 A. The Doppler h a l f - w i d t h of t h i s l i n e was measured from the p r o f i l e and c a l c u l a t e d to be l e s s than 3 km s e c " 1 . The i r r e g u l a r concave shape across the spectrum i s b e l i e v e d to be due to the poor low frequency response of the video a m p l i f i e r which was being c o r r e c t e d at the time of w r i t i n g . The wavelength s c a l e f o r o t h i s spectrum i s approximately 7 A per i n c h , which suggests that the much weaker emission l i n e appearing on the p r o f i l e o i s the HEI l i n e at 4921 A. I t i s worthwhile to p o i n t out that o o the r e l a t i v e i n t e n s i t i e s of the l i n e s at 4958 A and 4921 A i s about 100:1, yet the h a l f - w i d t h of both features i s approxi-mately the same. This would i n d i c a t e that there i s very l i t t l e charge spread over the tube t a r g e t at these i n t e n s i t i e s . The spectrum i n Figure 13 was taken from the s t a r o A r c t u r u s . The wavelength re g i o n i s 5250 A, again, the change i n s i g n a l amplitude across the p r o f i l e i s b e l i e v e d to be due to the poor low frequency response of the video a m p l i f i e r . Data was taken from Arcturus i n an attempt to detect the pre-sence of a magnetic f i e l d by l o o k i n g f o r the Zeeman E f f e c t . A n a l y s i s of these data i s yet to be completed. Figure 14 i s a s i n g l e spectrum of a sunspot i n the o wavelength re g i o n of 5250 A, the same s p e c t r a l region as the lunar spectrum of Figure 11. Data was taken from a sunspot to v e r i f y the experimental technique used i n o b t a i n i n g magnetic SPECTRUM OF ARCTURUS a a FIGURE 13 FIGURE 14 38 f i e l d data. The lower p r o f i l e of Figure 14 i s the d i f f e r e n c e between two s o l a r s p e c t r a ; one d e r i v e d from right-hand p o l a r i z e d s u n l i g h t and the other from l e f t - h a n d p o l a r i z e d s u n l i g h t . The s i n u s o i d a l c h a r a c t e r of t h i s d i f f e r e n c e p r o f i l e confirms a r e l a t i v e s h i f t of the s p e c t r a l features i n the l e f t - h a n d and r i g h t - h a n d p o l a r i z e d s p e c t r a , and hence i n d i c a t e s the presence of a magnetic f i e l d . Comparison of Figures 14 and 10 i n d i c a t e that the former shows s i g n i f i c a n t l y b e t t e r r e s o l u t i o n , although both s p e c t r a were taken under s i m i l a r c o n d i t i o n s . This discrepancy i s undoubtedly an i n d i c a t i o n of the t r a n s f e r f u n c t i o n of the l u n a r s u r f a c e . At the end of each o b s e r v a t i o n , a P o l a r o i d photograph of the o s c i l l o s c o p e d i s p l a y i s taken to be used as a reference whi l e working at the t e l e s c o p e . Figure 15 shows three photo-graphs taken from the system o s c i l l o s c o p e monitor. Figures 15a and 15b are the same sp e c t r a as Figures 12 and 10 respec-t i v e l y . These photographs were taken at the time of observa-t i o n . Figure 16 i s a s y n t h e t i c spectrum produced i n the l a b o r a t o r y to check the r e s o l u t i o n of the t e l e v i s i o n camera at d i f f e r e n t t a r g e t voltage s e t t i n g s . To produce the s y n t h e t i c spectrum, s t r i p s of f i n e wire 50 microns wide a l t e r n a t e w i t h 210 micron wide threads across the photocathode, w i t h t h i c k e r threads at e i t h e r end. Results from the s y n t h e t i c spectrum i n d i c a t e that the r e s o l u -t i o n of the t e l e v i s i o n camera, and hence the e n t i r e system i s about 0.1 to 0.15 m i l l i m e t e r s . 39 OSCILLOSCOPE PHOTOGRAPHS FIGURE 15a FIGURE 15b 40 SYNTHETIC SPECTRUM FIGURE 16 41 SUMMARY A d i g i t a l data a c q u i s i t i o n system has been developed to process analog data from an image isocon t e l e v i s i o n system. A des c r i p t i o n of the d i g i t a l l o g i c and e l e c t r o n i c s used i n the system has been given and some spectral data obtained with the system has been described. The r e s u l t s obtained to data i n d i -cate that the system as a whole performs as i n i t i a l l y intended and i s able to resolve spectral features of the order of 0.1 mm. Data a c q u i s i t i o n time i s less than 1.5 seconds per frame (1360 samples) and the data obtained appears to be very precise. Since most of the data processing time i s required for mag-ne t i c tape operations, a sixteen track magnetic disc i s being added to the system. This should reduce the data a c q u i s i t i o n time to less than 0.5 seconds. The data a c q u i s i t i o n system has also proved to have an a p p l i c a t i o n i n astronomical observations where fin e time resolution i s required. The system i s now being used to record d i f f r a c t i o n patterns from lunar occultations. In the near future the computer and interface w i l l be connected to a pulse counting photometric system which w i l l be used for observa-tions of r a p i d l y varying astronomical sources. 42 BIBLIOGRAPHY Goldberg, B. A., P e r s o n a l communication, Department of Geophysics and Astronomy, U n i v e r s i t y o f B r i t i s h Columbia, 1971. M i d d l e h u r s t , B. M. and A l l e r , L. H., Nebulae and I n t e r s t e l l a r M a tter, The U n i v e r s i t y of Chicago P r e s s , London, 1968. Motz, L. and Duveen, A., E s s e n t i a l s o f Astronomy, Wadsworth P u b l i s h i n g Company, C a l i f o r n i a , 1967. Nashelsky, L., D i g i t a l Computer Theory, John Wiley § Sons, New York, 1967. Nelson, P. D., Advances in Electronics and Electron Physics, ed. by J . D. McGee, D. McMullen and E. Kaham, V o l . 28A, p. 209, Academic P r e s s , London, 1969. R i c h a r d s , R. K., E l e c t r o n i c D i g i t a l Systems, John Wiley § Sons, New York, 1966. Smith, M. G., Weedman, D. W., I n t e r n a l Kinematics of Two B r i g h t HII Regions, The Astrophysical Journal, V o l . 160, p. 65, The U n i v e r s i t y of Chicago P r e s s , Chicago, I l l i n o i s , 1970. Wickes, W. E., L o g i c Design w i t h I n t e g r a t e d C i r c u i t s , John Wiley $ Sons, New York, 1968. 4o APPENDIX A DIGITAL LOGIC SYMBOLS A B NAND =r> o o I B O I I f I o A B NOR O O I I B O I O I I 0 0 O INVERTER A I O D TYPE FLIP-FLOP s C Q V,' _ D Q R tn tntl D Q Q O O si / 1 0 a , it Q = V MONOSTABLE MULTIVIBRATOR 1 ORG X' 50' 2 PE EQU 0 . 3 .CWPE. _.. _....EQU._ 0 EOU 1 5 RT S EQU 2 6 R TM EOU 2 7 MT EOU 3 8 SC EOU 4 9 F IGHT. ... EQU 4 10 ADC EOU 5 11 SW EOU 6 1? ONE EOU 7 13 TWQ EOU 8 14 OP EQU 7 . 1 5 . TT „_.ED.U 8 16 STAT EQU 9 17 R9 EQU 9 IB R I O EOU 10 19 R 11 EOU 11 20 R12 EQU 12 21 R .13 EQU 13._ 22 R 14 EQU 14 23 R15 EQU 15 24 STAR T L P SW * + 4 25 DC - X ' 0 0 0 0 • 26 DC A ( * + 1 4 ) 27. AODR DS 4H 28 SUM OS 2H 29 LHI O N E f l 30 L H I TWO , 2 31 L H I M T , X » 8 5 * LOAD D E V I C E NO. OF TAPE UMIT 32 LHI A D C , X « EO' D E V I C E NUMBER FOR ADC ..33. . _ L H I SC.,_8 ......DEVICE. NO...OF SCOPE. .. 34 BA L R15,WAIT 35 OC MT,WRTEOF WRITE EOF ON MAGNETIC T A P E 36 BLOCK LM R 1 4 , NDATA LOAD NO. OF DATA WORDS 37 STH R15 ,SUM+2 END ADDRESS OF BLOCK 3 38 SHR R 1 5 , R 1 4 . .39. .SI H _ R15.., AD.DR+6.. . .END....A.DDRESS .0F B.IOC K 2 40 AH R R15,TW0 41 STH R15,SUM S T A R T I N G A D D R E S S OF BLOCK 3 4? AH R R 1 4 , R14 A3 SHR RI 5 , R 1 4 44 STH R 1 5 , ADDR +4 S T A R T I N G A D D R E S S OF BLOCK 2 .. 45 . ..SHR _R15,TW0 . 46 STH R l 5 , A D D R + 2 E N D I N G ADDRESS OF BLOCK 1 47 SHR R 1 5 , R 1 4 48 AH P. P15 ,TWO 49 STH R 1 5 » A D D R S T A R T I N G ADDRESS OF BLOCK 1 50 * T H I S SECT ION ZEROS THE B L O C K S OF STORAGE 51 . I R.IK. LHJL. . J U 3 , R 1 5 _ 52 l.HR P. 1 4 , TWO 53 LH R 1 5 , SUM+2 54 XHR R l ? , R l ? 5 5 ST H R12,0(R13 ) 56 BXLE RI 3 f*-a 57 * 50 nc AOC.INIT ZERO STATUS BITS IN ADC 59 * THIS SECTION ZEROS THE REGISTERS 60 RETURN X HR PE.PE RO HAS THE NO. OF PARITY ERRORS 61 XHR NBLK,NBLK Rl. HAS NO. OF BLOCKS READ 62 XHP. RTStRTS .63 ST H ..... .PE, ENDS'W ... 64 STH PE tRSUM6 65 STH NBLK,COUNT 66 STH nbi.k.OWPI 67 STH NBLK,QWPERR 63 STH NBLK tTP ERR 69. * ... 70 SSR ADC,STAT CHECK STATUS OF ADC 71 BTC 7,EP.RTS BRANCH IF DATA TOO SOON 72 RET RAL R15,AnC0N PREPARE ADC TO READ DATA 73 * THIS SECT ION MAKES THE COMPUTER WAIT UNTIL DATA HAS BEEN RECEIVED 74 SSR ADC,ST AT 75 .... BEX ...7,.*-2.. ... WAI T FOR STATUS. BIT TO BE SET 76 RET2 BT C 5 » E R R T M BRANCHES IF TOO MUCH DATA 77 * THI S SECTION. CHECKS HOW MUCH DATA HAS BEEN READ IN 78 R LAST OC ADC,RD AO PREPARE TO READ END ADDRESS 79 RO R ADC,Rl2 HIGH ORDER BYTE 80 RD R ADC t Rl 3 LOW ORDER BYTE S 1 SLHL .R12, 8 .. _ _ SHIFT. HIGH ORDER BYTE LEFT ... 82 AMR R12tR13 83 STH R12,RLAST2 84 85 OC A D C » I N IT ZERO ADC STATUS BITS 86 -X. ... 87. ..*.... THIS . S EC.T..ION..„CHE.CK S....FOR QUARTER. WAVE PLATE, ERRORS. 88 OWP LH R13 , ADDR 89 LH R10,0(R13) 90 LH R 15, COUNT 91 BZ 0WP02 92 LH R l l t 0(R13) 93. .... XH -R11,.QWR1: . _ 94 NH R Rl1,EIGHT 95 BNZ QWP 02 96 LH R15.CWPFRR 97 AH R Rl5,ONE 98 STH R15,QWPERR ° 9 -QWRQ.2. . S.LH RIOtOWPl _ 100 STH ONE,COUNT 101 L HR R14, TWO 1 02 LHR R12,R13 103 LH Rl5,ADDR+2 104 QWP03 LH R11,0(R13) 105 XH _R1.1 ,0(R12) 106 NH R R11,EIGH T 10-7 BNZ 0WP01 108 BXLE R13 .0WP03 ~ 109 B PRTY 110 QWP01 AH R QWPE,ONE 111 .SHR .. .R13.R12.. . - -112 SRHA R13,1 113 STH R13,NREAD 114 ! H SW.SWITCH 1 1 5 NH I SW.X'OOOV CHECK IF TELETYPE IS DISABLED. 116 BZ PR TY 1 17 * THIS SECTION PREPARES BYTES OF DATA TO BE OUTPUT ON THE Tt LETYFE 118 A SC I I XHR RI4 , RI4 ZERO BUFFER COUNTER. 119 XHR R l OfR l 0 120 AS C I I 05 LB P11,NRFAD(R10) LOAD BYTE IN R 11 121 LBR R12 ,R1 1 122 SRHL R l l , 4 HIGHER ORDER 4 BITS IN R l l •123 NH.L_._. R12, X'OOOF V .. . .... . . LOWER ORDER 4 BITS IN R12. 124 XH R R15,R15 125 ASC I 101 XHR R13.R13 1 26 CI.HI R l 1 , X ' 0 0 0 A « 127 BTC 8,ASCI 103 BRANCH IF HEX CHAR. IS A NUMBER . 128 LHI R13,X'0007* 129 ASCI I 03. AH I .RLl'f X!0030MR13).. . .TRANSLATE HEX CHAR. TO ASCII 130 STB Rl 1 ,3UFF(R14) STORE IN BUFFER 131 AHR R14, ONE ADD ONE TO BUFFER COUNTER 1 32 l.H R PI 5 , Rl5 CHECK WHETHER THROUGH WITH BYTE . 133 BP A SCI I 02 BRANCH IF THROUGH 134 AHR R15,0NF 135 LHR R1.1 ,.R12.. LOAD.LOWER ORDER .BITS INTO R l l 136 B A SCI I 01 137 ASCI 102 LHR RIO, RIO CHECK IF THROUGH WITH HALF WORD. 138 BP ASCI IC4 BRANCH IF THROUGH 139 AHR RIO,ONE 1 40 B ASCI 105 _ 141 A SCI I 0.4 _L.HI _R.1.2.t.X« QD_Q&_'__ - _ 142 STH R12,BUFF(R14) PUT CARR. CONTROL CHAR. [N BUFFER. 143 * OUTPUT ROUTINE FOR TELETYPE TO WRITE MESSAGE 144 OUPT LHI R 13,BUFF 145 LHI R14, BU FF+5 146 OC TT,INIT INITIALIZE TELETYPE. 147. W RR JX,JU3. _ __ .. ...0U.TPUT . _MESSAGE. 148 * 149 * ROUTINE TO CHECK PARITIES OF A BLOCK OF DATA FROM THE ADC 150 PRTY LH R13» A DOR STARTING ADDRESS 151 * THIS SECTION DETERMINES THE PARITY OF A SINGLE DATA WORD 152 PR TY02 I.H R12 ,0(R13) LOAD DATA INTO P12 15.3.. .... XHR Rl 1,R11. 154 LHI R10,15 155 PR TY04 SLHL R12 ,1 SHIFT WORD LEFT ONE BIT 156 BFC 8,PRTY03 BRANCH IF BIT 0 = 0 1 57 AHR Rl1 ,ONE R l l KEEPS COUNT OF BITS - 1 153 PRTY03 SHR RIO,ONE . .159. _ 3.2. ..PRTY 04 BRANCH_IF. NOT ..THROUGH WITH WD 160 SRHL R l l ,1 CHECK IF ODD NO. OF BITS = 1 161 BC PRTY06 BRANCH IF ODD 162 AH I PE,X'0100' 163 PR TY06 BXLE R13 ,PRTY0? 164 * CHECK WHETHER . DATA IS TO BE PUT ONTO MAGNETIC TAPE . 165 _..EAI R15 ,Dp.SW 166 NHR SW,E IGHT 167 BZ RD IS 168 * THIS SECTION PUTS THE DATA ON MAGNFTIC TAPE 169 XHR R10,R10 1.70 WTMT LM R13,ADDR 171 ___.AH R R14,0NE. 172 BAL R 15, WAIT WAIT FOR NMTN = 1 173 OC MT , WRITE WRITE OPERATION 1 74 WR R MT .Rl^ WI TF PT OCK 175 SSR MT ,ST AT 176 NH I STATjX'Cl1 ERR, EOF, DU MUST = 0 177 BNZ WTMT01 BRANCH IF ABNORMAL WRITE 178 * BACKSPACE AND READ DATA 179 BAL R l 5 » W A I T 1 80 OC MT.BKSP BACKSPACE TO EOF MARK 181 L M R13 , ADDR+4 182 AHR Rl4,ONE 183 ._ BA! _R 15, WAIT 1 84 OC MT , RFAD 185 RBR MT.R13 READ BLOCK 1 86 * THIS SECT TOM CHECKS WHETHER THE TWO BLOCKS AR F IDENTICAL 187 LH Rl3,ADDR 188 LHR R14,TWO . .189 ._ 1 ..... . ..LH .R1.5, ADDR+2. . . . ._ _ 1 90 LH R12,A0DP>4 191 WTMT02 LH R l l , 0(R13) 1«5? XH Rll,0( P I 2 ) 193 BNZ WTMT01 194 AHR . R12,TWO 19 5 BXLE... Rl 3,WTMTO? 196 AHR NBLK.ONE 197 BAL R15,WAIT 198 or. MT,WRTEOF 199 B EOT 200 * THIS SECT ION BACKSPACES THE TAPE AND CHECKS HOW MANY TIMES ... ...201. f THE ..BLOCK—HAS ..BEEN READ _ _. ... . _ _ . 202 WTMTO 1 BAL R I 5, WA I T 203 OC MT , BKS P 2 04 AH R Rl CONE 205 CL HR RIO,EIGHT 206 BL WT MT ... 207 * I F R E AQ....D.AT.A. ,bl^S_^lLm^LG.HT_TJil£Sj_A__BLO_CK...OF_ONES W ILL BE. RUT.ON.-_ 208 * THE TAPE 2 09 WTMT03 LH R10,A0DR+4 210 LHR Rll,TWO 211 LH R12.ADDR+6 212 WTMT04 STH 0NE,0(R10) .21.3. B X L £ _ R 1.0.t.WXMJ.04 . . . . . . 214 BAL R15,WAIT 215 OC MT,WRITE 216 WB MT,ADDP+4 217 LH Rl5tTPERR 218 AHR Rl5,ONE . _2 1.9.. . -STH Rl 5, TPFRR 220 EOT SSR MT , S T AT 221 NH I STAT,X'20' 222 BNZ EM OTP 223 * THIS SECTION WRITES DATA ON THE DISPLAYS 224 RDI S LHR R13 ,QWPE 225 NH I. .RL3»_X«.0E0E..I .. ... . . 226 LHR Rl 5 t RTM 227 NH I R 1 5 , X • OF OF • 228 SLHL R15. 4 229 AH R R13,R15 230 STH R13,RDSPLY .231 . LHR __ ..Rl 3 , NBLK 232 NH I R 1 3 , X « 0 0 F F ' 233 LH R14,0WPERR 2 34 MHI R H . X ' o n n F ' 235 SI.HL R 1 4 , 1 2 236 AHR R13,R14 237 LH Rl4,TPERR 238 NH I R14,X* OOOF• 239 SLHL R14, 8 240 AHR R 1 3 , R1 4 241 STH R13,RDSPL Y + 2 242 LH I Rl 4,RDS PLY 243 OC .... DP,I NCR . . 244 WD DP , 3 ( R 14 ) 245 WD OP,2 (P14 ) 246 WD DP ,1(R14) 247 WD DP,0(R14) 248 OC DP,NORM 2.49 * SEE. IF R SUM . I S TO .BE ZEROED. 250 LH SWtSW ITCH 251 NH I SW,X'40001 2 52 BZ RSUM5 253 X HR R15,R15 2 54 STH R15,RSUM5 2 55. LH.. _ ___R1.2.,.SUM 2 5 5 LHR R13,TW0 2 57 LH R14,SUM+2 258 STH R15,0(R12) 2 59 BX LE R12,*-4 260 * SEE IF RSUM IS TO BE CALCULATED. 261. RSUM 5.. _. ...LH SW ..SWITCH . ... .... . . ... 26 2 NH I SW ,X'8000• 263 BZ CKEND 264 RSUM LH R14,SUM+2 265 LHR R13 ,TWO 266 LH R12,SUM 267 .LH RLLfAQDR . _ _ 268 R SUM4 LH RIO,0(Rll) . 269 LH R15, 2 ( R U ) 27 0 LH SW ,SW ITCH 27 1 NH I SW , X' 2 000* 272 BZ RSUM12 .273 LH .. .SW,SWJTCH ,. ._ _._ ...... 274 NH I SW,X« 1000' 275 BZ RSUM 1 276 LHR R10.R15 277 B RSUM1 273 RSUM 12' LH SW,SWITCH .. 279. . NHI_ . S W . X » 1 0 0 0 • 2 80 BZ R5UM9 281 LHR R9 , R 10 2 82 SLHL R9 ,1 283 XHR R9,R10 2 84 NH R R9,EIGHT . .285 BZ.._ ..._RSU.M11 .. . ... .. . ... . 286 B RSUM 7 2 87 RSU.M9 LH SW ,SW ITCH 28 8 NH I SW,X'0800' 289 BZ R SUM 7 290 RSUM11 SHR RIO , Rl 5 291 . _B_ .. ..R.SUM1. ... ... 2 92 RSUM7 SHR R15.R10 293 LHR R10,Rl5 R SUM i LH R 1 S,RSMM6 2 95 SRHA RIO ,0(P.15 ) 296 LHR R9,R10 297 LH R15» 0(P 12) 298 AHR R10.R15 299 XHR R9,R 15 3 00 X HR Rl 5, RIO 301 NHI R l 5,X» 8000' 302 BZ RSUM3 3 03 . N H I . . . .R9.XV8 000.' ... _ . 304 BNZ RSUM3 305 * 3 06 LHR R10.R12 307 LH R12, SUM 308 RSUM2 LH R15,0(P12) ..309. . „_,_ _ ~ . S R . H A _ 115.,! . . . . 310 STH R15,0(R12) 311. BX LE R12,RSUM2 312 1 H R R12.R10 313 LH R15,RSUM6 314 AHR R15,0NE .. .315. STH. _ _R1.5.,.RSUM6 . .. .... . _ . . . 316 B RSUM4 317 RSUM3 STH R10,01R12) 31 3 R SUMS AH I R l 1 ,4 319 BXLE R12,R SUM4 320 * CHECK WHETHER END OF STAR OR END OF TAPE .. 321 .CKEND..... L.H SW, SWITCH .... 322 N M R SW,ONE 323 BNZ ENDST 324 l.H SW,SWITCH 32 5 NHR SW.TWO 326 BNZ END TP ... 327_ B At R15,A DCON 32 8 B SCOPE 329 * THIS SECTION HANDLES THE END OF A RUN ON A STAR 330 ENDST BAL R15.WAIT 331 OC MT , WRT EOF 33 2 LHI R 1 5 , X « 0 0 8 0 ' .333 - - S . T - H R l 5, RESTRT. . 334 B SC0PE4 335 * THIS SECTION HANDLES THE END OF TAPE 33 6 ENDTP BAL R 15. WAIT 337 OC MT,WR TEOF 338 BAL R 15, WAIT 339. OC MT F WRT FOF 340 BAL R 1 5 , WA I T 34 1 OC MT,REWIND 342 LHI R15, X' 0050 » 343 STH R l5 , R E STRT 344 -r* .345 * THIS . .SECTION.. ..OUTPUTS. THREE. LINES ON THE -SCOPE.-IN THE T-Y MODE 346 a. 347 SC0PF4 STH ONE,ENDSW 3 48 SCOPE IH Rl 4 , ADOR+2 349 LHI R13,4 350 LH SW,SWITCH • . .. 351 ... NHI SW,X ,..0400_». 3 52 BZ SC OPE 2 35 3 LH R 12, ADDR 3 ^ PAI Pi 5 ,<:CnoF8 355 3 56 SC0PE2 LH SW,SWITCH 357 NH I SW,X'02 00» 358 BZ SC0PE3 359 LH R12 , ADDR 3 60 AHR R12,TW0 361 BAL R15,SCOPES 3 6? * 363 SC0PE3-. LH SW,SWITCH 3f4 NH I SW,X * 01001 365 BZ SCOPES 3 66 LH R 1 4, SUM+ 2 36 1 LH R12 , SUM 3 68 LHR . R13,TW0 369 BAL R15,SC0PE8 . . . 370 371 SCOPE 5 BAL R15,DP SW 37? LH Rl 5, ENDSW 373 BNZ SC0PE7 .374 NH I SW , 3 375 _. B.N Z ...CKE.ND. 376 <** 377 SSR ADC,STAT 378 BTC 7,RET2 379 B SCOPE 380 * . .3 8.1. SCO P.E 7. NH I SW ,3 ... ... _ . 382 BNZ SCOPE 383 LH R15,RESTRT 3 84 B 0IR15 ) 385 386 SC0PE8 OC SCINITSC 3 87. OC SC .TRIG 388 SCOPE 9 SSR SC , STAT 389 BTC X« F » » S C 0 P E 9 390 WD SC,0 (R12 ) 391 WD SC , 1 ( R 12 ) 392 BX LE R12,SC0PE9 _ 3 93. BR. R15 394 * 395 ERRTS AH I R T S , X ' 0 1 0 0 « 396 LH I R 1 5 , X' OA 00 * 397 SHR R15.0NE 3 93 BP *-2 3 99 . SL RET 4 00 -<-401 ERRTM BTC 4 ,*+8 4 02 B ERRTS 403 AHR RT M, ONE 404 B RLAST .* THIS . SECTION RE ADS. THE SW ITCHES ..INTO. REG I.STEPS SW 406 DPSW OC DP,I NCR SELECT INCREMENTAL MODE 407 RDR OP- f SW 408 R OR DP , R 14 409 OC DP,NORM SELECT NORMAL MODE 410 SLHL R14,8 411... AHR _.S.W,.R1.A. 412 STH SW,SWITCH 413 BR R 15 414 * THIS SUBPROGRAM PREPARES THF A DC INTERFACF TO RFAD DATA 415 * CALL INC. SEQUENCE 4 1 A * BAL R15,ADCON 41 7 * 4 1.8 A0C0N OC ADC,IN IT INITIALIZE ADC FOR ADDRESS 419 WD ADC,ADDR HIGH ORDER BYTE OF STARTING ADDRESS 47 0 WD ADC,ADDR+1 LCW ORDER BYTE OF STARTING ADDRESS 421 WD ADC,ADDR +2 HIGH ORDER BYTE OF ENDING ADDRESS 42? WD ADC,ADDR+3 LOW ORDER BYTE OF ENDING ADDRESS 4 23 .... ..SSP ADC , STA.L. . .... _ 424 BTC 1, ERRTS BRANCH IF DATA SENT TOO SOON 42 5 OC ADC,AON OKAY,ENABLE INTERFACE 4?6 BR R 1 5 42 7 * 478 WA I T SSR MT,STAT .429 NH I ... STAT , X MO! 430 BZ WAIT 4 31 BR Rl 5 4.3? RUFF OS 3H 433 NREAO OS 1 H 4.34 TPERR DS IH . 435 NCAJ_A... DC.. X!0.5..50«. ... 43 6 DC X'1 FFE1 43 7 SWI TCH DS IH 43 8 OWPERR DS IH 439 QWP1 DS IH 440 COUNT DS IH 441.. . RL AS.TJL DS— __.1H , . . ....... 442 R 0 S P L Y DS 2H 443 RSUM6 DS IH 44 4 FNDSW DS IH 445 RE STRT DS IH 446 w RTEop DC X'301 . 447.. . WR.IJ.E_. DC_ _ X.LA2 • „. 443 RKSP DC X' 91» 449 READ DC X« Al • 450 TRIO DC X'20« 451 ROAD DC X' 84' 452 I NIT DC X •93t . 453 I..NCR DC... X±4.0 1 . . . . . • • 454 NORM DC X" 80« 455 INITSC DC X • 10 • 456 AD N DC X» AO* 457 REWIND DC X « 3 8 ' 45 3 END T ABIL I TY QWPE 00 00 F NBLK 0001 F RTM 0002 F MT 0003 F EIGHT . 00 04. . F. _ .__ADC 0.005.._ ..F _ ONE 0007 F TWO 0008 F TT 0008 F STAT 0009 F Rl 0 000 A F R l l OOOB F R13 00 OD F R14 OOOE F START 0050 F A DDR 0C58 F BLOCK 00 80. _ F_. Z BLK OOAA... • . . R c T 00 E 4 F RET2 OOEE F OWP 0 108 F QWP 02 0 130 F QWP01 01 56 F ASCI I 0 16F F 

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