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An on-line computer assisted mass spectrometer Mitchell, David Laurie 1971

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AN ON-LINE COMPUTER ASSISTED MASS SPECTROMETER  by  DAVID LAURIE MITCHELL B.Sc,  King's College London, 1968  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 thesis as conforming to the required standard  THE UNIVERSITY OF BRITISH COLUMBIA A p r i l , 1971  In presenting this thesis  in p a r t i a l fulfilment of the requirements for  an advanced degree at the University of B r i t i s h Columbia, I agree that the Library shall make it freely available for reference and study. I further agree that permission for extensive copying of this  thesis  for scholarly purposes may be granted by the Head of my Department or by his representatives.  It  is understood that copying or publication  of this thesis for financial gain shall not be allowed without my written permission.  Department of The University of B r i t i s h Columbia Vancouver 8, Canada  0  ABSTRACT  An analog data a c q u i s i t i o n system i n c o r p o r a t i n g an I n t e r d a t a Model 4 d i g i t a l  computer has been designed and b u i l t  for  T h i s system has been c o n c e i v e d with  a mass spectrometer.  the primary  o b j e c t i v e s o f improving  production.  a n a l y t i c a l p r e c i s i o n and  Automated mass spectrometer  o p e r a t i o n allows f o r  the c o l l e c t i o n o f l a r g e r q u a n t i t i e s o f data while d e c r e a s i n g o p e r a t o r involvement  and consequently d i m i n i s h i n g o p e r a t o r  b i a s and f a t i g u e . The ing  analog s i g n a l from the mass spectrometer  system i s d i g i t i z e d u s i n g a d i g i t a l  measur-  v o l t m e t e r and t r a n s -  m i t t e d , v i a an i n t e r f a c e , t o the p r o c e s s o r where the d i g i t a l i n f o r m a t i o n i s manipulated gram.  i n accordance  An a d d i t i o n a l f a c i l i t y  w i t h a computer pro-  i s p r o v i d e d whereby d i g i t a l  data  from the p r o c e s s o r can be d i s p l a y e d , i f d e s i r e d , on a 5 decade numerical readout  s i t u a t e d a t the mass spectrometer  console.  Hardware i s a l s o a v a i l a b l e i n the i n t e r f a c e to p r o v i d e c o n t r o l of  the magnetic f i e l d  the mass spectrometer  scan r a t e .  console allows the o p e r a t o r to convey a  v a r i e t y o f predetermined  i n s t r u c t i o n s t o the computer a t any  time d u r i n g the course o f a run. on-line  A f u n c t i o n c o n t r o l switch a t  Thus, the system p r o v i d e s f o r  ( r e a l time) data p r o c e s s i n g o f mass s p e c t r a as w e l l as  l i m i t e d computer c o n t r o l over the mass  spectrometer.  T h i s t h e s i s i s p r i m a r i l y concerned  w i t h the d e s i g n  and c o n s t r u c t i o n o f the l o g i c hardware f o r t h i s system t o g e t h e r w i t h a demonstration  of i t s operating a b i l i t y .  iii  TABLE OF CONTENTS  ABSTRACT  i i  TABLE OF  CONTENTS  L I S T OF  FIGURES  L I S T OF  TABLES  i i i v vi  ACKNOWLEDGEMENTS CHAPTER 1.  v i i  INTRODUCTION 1.1  General  1.2  Design  CHAPTER 2  Background Objectives  GENERAL DESCRIPTION 2.1 2.2  The The  2.3  Programming  CHAPTER 3  THE  Mass S p e c t r o m e t e r Computer the  I n t e r d a t a Model  INTERFACE HARDWARE DESIGN  3.1  Introduction  3.2  Device  3.3  D a t a and  Status  3.4  D a t a and  Command  3.5  Interrupt  3.6  Read/Write  3.6.1  Read  3.6.2  Write  Addressing Input Output  Control Sequencing  Operation Operation  3.7  The  Analog-to-Digital  3.8  The  Numerical  3.9  Construction  Converter  Display o f the  CHAPTER 4  ON-LINE FILTERING OF  CHAPTER 5  SYSTEM 5.1 5.2 5.3  4  Interface DATA  PERFORMANCE  Introduction P r e p a r a t i o n o f S t r o n t i u m Samples A n a l y s i s o f E i m e r § Amend SrC03 I n t e r l a b o r a t o r y Standard  5.4 CHAPTER 6  A n a l y s i s o f Strontium i n a Rock Sample CONCLUSIONS  BIBLIOGRAPHY APPENDIX I  Ion Current  A m p l i f i e r and Output A t t e n u a t o r  Circuit  II  Scan Drive  III  Summary o f I n t e r d a t a  IV  Mass Spectrometer I n t e r f a c e Programming Guide  Circuit Programming  Instructions  V  LIST OF FIGURES FIGURE 1.  COMPUTER TO MASS SPECTROMETER INTERFACE  FIGURE 2.  ANALOG DATA ACQUISITION SYSTEM BLOCK DIAGRAM  Page 4  8  FIGURE 3.  THE MULTIPLEXOR  FIGURE 4.  BASIC LOGIC FUNCTIONS AND TRUTH TABLES  16  FIGURE 5.  DEVICE ADDRESSING,  21  FIGURE 6.  DATA AND STATUS INPUT, LOGIC DIAGRAM  23  FIGURE 7.  DATA AND COMMAND OUTPUT, LOGIC DIAGRAM  24  FIGURE 8.  INTERRUPT CONTROL, LOGIC DIAGRAM  26  FIGURE 9.  COMPUTER/MASS SPECTROMETER INTERFACE READ/WRITE LOGIC EXTERNAL CONNECTIONS TO READ/WRITE  29  SEQUENCING  30  FIGURE 10.  CHANNEL  LOGIC DIAGRAM  LOGIC  FIGURE 11.  READ SEQUENCING  FIGURE 12.  WRITE SEQUENCING  FIGURE 13.  ANALOG-TO-DIGITAL CONVERTER BLOCK DIAGRAM DUAL SLOPE WAVEFORMS FOR DIGITAL  35  VOLTMETER  36  FIGURE 15.  THE NUMERICAL DISPLAY  38  FIGURE 16.  MASS SPECTROMETER FILTER -DISPLAY PROGRAM FREQUENCY RESPONSE OF DIGITAL FILTER  43 46  FIGURE 14.  FIGURE 17.  INSTRUCTIONS  10  INSTRUCTIONS  32 32  vi  LIST OF TABLES Page 7  TABLE I  DATA PROCESSING EQUIPMENT PURCHASED  TABLE II  SPECIFICATIONS OF QUAD 2-INPUT NAND FUNCTION FOR THE FIVE LOGIC FAMILIES  18  INTEGRATED CIRCUIT PACKAGES USED IN CONSTRUCTION OF INTERFACE LOGIC CIRCUITRY  40  TABLE IV  RESULTS OF ANALYSES OF EIMER AND AMEND INTERLABORATORY STANDARD SrCOj  54  TABLE  RESULTS OF ANALYSES OF GREY ARGILLITE  54  TABLE I I I  V  ACKNOWLEDGEMENTS The success of this project owes a great deal to the various people,who assisted the writer. The project was i n i t i a t e d by Dr. R. D. Russell whose thoughtful guidance, enthusiasm and encouragement throughout were always  appreciated.  Special thanks go to J . Blenkinsop who wrote the necessary computer programs, imparted much useful advice, and was responsible f o r the well-functioning of the mass spectrometer. The writer i s indebted to the technical s t a f f of the Department of Geophysics, U.B.C, i n p a r t i c u l a r C. Croucher, R. D. Meldrum, and E. J . B e l l i s whose specialized s k i l l s made a large contribution to the project. Thanks must also go to B. D. Ryan who provided the writer with much needed geological enlightenment and to Dixie Pidgeon f o r typing this thesis. The Data Technology Corporation and Interdata  Incor-  porated, very kindly gave permission f o r the reproduction of several pages from their equipment manuals. The entire computer system was purchased from funds granted to Dr. R. D. Russell by the National Research Council of Canada, Mobil O i l Canada, Ltd., and the Standard O i l (Indiana) Foundation, Incorporated. F i n a l l y , the writer wishes to thank Dr. T. J . Ulrych whose c r i t i c a l appraisal of the manuscript i n i t s f i n a l stages made f o r a greatly improved thesis.  CHAPTER 1 INTRODUCTION 1.1  General Background During the past few years a number of important  advances have been made i n the f i e l d of isotope geophysics. New a n a l y t i c a l techniques, such as the double spiking procedures of Compston and Oversby (1969) and the t r i p l e - f i l a m e n t technique for lead (Catanzaro, 1967), benefit from a high order of precision i n mass spectrometer analysis.  In order  to do f u l l j u s t i c e to these improved a n a l y t i c a l techniques i t i s necessary to increase the measurement precision of mass spectrometer ion-currents.  One way i n which this can be  achieved i s by means of d i g i t a l data c o l l e c t i o n and analysis procedures.  Using an on-line d i g i t a l computer, Wasserburg  and his associates at the C a l i f o r n i a Institute of Technology have demonstrated the value of these procedures by achieving results of outstanding precision on analyses of strontium (Papanastassiou and Wasserburg, 1969) and gadolinium (Albee et a l , 1970) . At the University of B r i t i s h Columbia, research of d i g i t a l data c o l l e c t i o n systems commenced i n 1963, using a gas-source mass spectrometer.  A servo-voltmeter ion-current  amplifier (Stacey et a l , 1965) was u t i l i z e d which had, as a primary output, the shaft rotation of a motor-driven potent-  2.  iometer.  Thus analog — t o - d i g i t a l conversion was e a s i l y  achieved using a shaft position encoder (Weichert et a l , 1967) . D i g i t a l data was i n i t i a l l y stored on punched paper tape but, as the system was developed, the paper tape punch was replaced by an incremental magnetic tape recorder. In both cases, the data was processed using the f a c i l i t i e s of the University's Computing Centre which presently include a duplex IBM 360/67 computer. To maintain completely independent data acquisition systems for the three mass spectrometers operated by the Department would have required the purchase of two more tape recorders, and the construction of suitable interfaces.  A  small d i g i t a l computer was therefore purchased i n 1969 and work began on the design of a suitable d i g i t a l logic interface to a mass spectometer.  The on-line data acquisition system  that was subsequently b u i l t i s capable of immediately and simultaneously supervising the operation and processing the data from the three mass spectrometers, which are used at different times for isotopic analysis of Pb, Th, U, Rb, Sr, Gd, Eu and Sm. The system description presented i n this thesis i s intended as an example of what i s possible and no claim i s made that the design i s optimum i n any sense.  3.  1.2  Design O b j e c t i v e s The  system was conceived w i t h three main o b j e c t i v e s  i n mind: 1.  A decrease  i n the o v e r a l l  data from the mass 2.  time r e q u i r e d t o p r o c e s s the  spectrometer.  A r e d u c t i o n i n o p e r a t o r involvement  of  o p e r a t o r b i a s and o p e r a t o r  3.  An i n c r e a s e i n a n a l y t i c a l  and hence a r e d u c t i o n  strain. precision.  These o b j e c t i v e s have been r e a l i z e d by u s i n g an o n - l i n e d i g i t a l computer i n t e r f a c e d to the mass spectrometer. digital  The computer  should be a b l e t o f i l t e r  the incoming  and d i s p l a y the f i l t e r e d  data p o i n t s a t the mass  console f o r the o p e r a t o r ' s convenience. be p o s s i b l e t o reduce  data i n r e a l  time  spectrometer  In a d d i t i o n , i t should  the mass s p e c t r a from the i n p u t data and  d i s p l a y the r e s u l t s a t h i s r e q u e s t .  The computing system should  have the c a p a b i l i t y o f a u t o m a t i c a l l y a d j u s t i n g the o p e r a t i n g c o n d i t i o n s o f the mass spectrometer. facility  for controlling  The system b u i l t  the magnetic scan r a t e but a d d i t i o n a l  c o n t r o l f e a t u r e s may be added a t a l a t e r  time.  The w r i t e r ' s r e s e a r c h was p r i m a r i l y concerned the d e s i g n and c o n s t r u c t i o n o f the n e c e s s a r y d i g i t a l for  has the  the i n t e r f a c e t o g e t h e r w i t h a demonstration  with  electronics  of i t s operating  ability. A s i m p l i f i e d b l o c k diagram o f the computer t o mass spectrometer  i n t e r f a c e i s shown i n F i g u r e 1.  SCAN PARAMETERS  READ  FUNCTION SELECT SWITCH  READ  SCAN RATE CONTROL  WRITE  DATA READY ION  EEATT  ION CURRENT AMPLIFIER  INTERFACE  4-DIGIT DIGITAL VOLTMETER  "HsECTION-2  43  feet  CABLE  ±  INTERFACE ^SECT]ION-1  INTERDATA MODEL-4 DIGITAL OMPUTER  %  CHART RECORDER  WRITE  DISPLAY^  V PEC 7-TRACK SYNCHR. TAPE RECORDER  FIGURE 1.  COMPUTER TO MASS SPECTROMETER INTERFACE  5.  CHAPTER 2 GENERAL DESCRIPTION 2.1  The Mass Spectrometer The mass spectrometer used i n this research project  was designed p r i n c i p a l l y by R. D. Russell i n cooperation with F. K o l l a r , J . S. Stacey and T. J . Ulrych, and was brought to i t s present state of operating e f f i c i e n c y by J . Blenkinsop. It i s a 90-degree sector, 30 cm radius, s o l i d source machine, with single order focussing and a variable magnetic scan.  field  In the past and at present this machine has been used  for rubidium-strontium analyses but i t i s i n no way limited to these elements. The analog  section of the mass spectrometer  measuring system incorporates a hybrid amplifier using an electrometer vacuum tube and integrated c i r c u i t components. The voltage output from this amplifier can be attenuated by factors of 1, 1/3, 1/9, 1/27, 1/81 using a shunt switching network.  The schematic c i r c u i t s for the ion current amplifier  and output attenuator, both designed by R. D. R u s s e l l , can be found i n Appendix I. The analog  output of the measuring system, which  i s generally of the order of one volt for most isotope peaks, i s fed to a d i g i t a l voltmeter which displays the input voltages and also functions as an analog computer interface.  - t o - d i g i t a l converter for the  6.  2.2  The Computer An Interdata Model 4 computer was chosen c h i e f l y  because of i t s v e r s a t i l i t y at a reasonable cost.  In addition,  i t uses a halfword length of 16 b i t s and a programming language that i s s i m i l a r to the University of B.C.  IBM 360/67  computer with which i t can be e a s i l y interfaced i f required. The 8k 8-bit bytes of memory supplied with the Model 4 Processor are marginally adequate for sophisticated mass spectrometer control and data reduction programs, however additional memory modules may be added, up to a maximum of 65k bytes, at any  time. A Teletype Model ASR33 and Peripheral Equipment  Corporation PEC 3520-72 synchronous tape transport were purchased with the Model 4 Processor  (see Table I ) . The teletype  was supplied ready interfaced to the computer and the tape transport was interfaced i n our laboratory by R. D. Meldrum using l o g i c c i r c u i t r y of his own  design.  Figure 2 shows the complete analog data a c q u i s i t i o n system for one mass spectrometer.  The processor can communicate  with the teletype and mass spectrometer v i a a multiplexor channel which has the capacity to handle a t o t a l of 256  devices.  Each peripheral device i s connected v i a a device c o n t r o l l e r to the multiplexor bus, i t i s this c o n t r o l l e r that provides interface between the computer and an external device.  the The only  essential requirement of the device i s that i t can supply data to the device c o n t r o l l e r i n an acceptable d i g i t a l format.  In  7.  TABLE I  DATA PROCESSING EQUIPMENT PURCHASED  MANUFACTURER  APPROXIMATE COST (1969)  PROCESSOR  INTERDATA INC.,  $7,800  *  8,192 BYTE MEMORY  INTERDATA INC.,  $6,000  *  SELECTOR CHANNEL  INTERDATA INC.,  $2,900  *  HIGH SPEED ARITHMETIC  INTERDATA INC. ,  $1 ,500  *  TELETYPE  $1,900  ITEM  MODEL NUMBER  § INPUT/OUTPUT TYPEWRITER $ PAPER  ASR33  CORPORATION  TAPE READER/PUNCH MAGNETIC TAPE  PEC  PERIPHERAL EQUIP- $4,000  TRANSPORT  3520-72  MENT CORPORATION  DIGITAL VOLTMETER  DT-344-2  DATA TECHNOLOGY  $  500  $  300  $  60  CORPORATION NUMERICAL DISPLAY  DS-103-5  DISPLAY GENERAL INCORPORATED  POWER SUPPLY  PS-200  DISPLAY GENERAL INCORPORATED  * - 1971 PRICES ARE ABOUT 401 LOWER THAN 1969 PRICES  8.  CORE MEMORY  HIGH  SPEED M E M O R Y  BUS  PROCESSOR MULTIPLEXOR CHANNEL  ~2W  MULTIPLEXOR  BUS  TS  7K  SE-  DEVICE CONTROLLER  J DEVICE"^ CONTROLLER*  1  SCAIM RATE CONTROL 32.  SELECTOR CHANNEL  SELECTOR  BUS  DATA READY  TELETYPE DVM  DEVICE ^ONTROLLEF;  SHUNT SELECTOR  DISPLAY  ION CURRENT AMPLIFIER  READ M.S. PARAMETERS  MAGNETIC  MASS SPECTROMETER. Figure 2.  A n a l o g Data Acquisition System Block  TAPE  Diagram  the case of the mass spectrometer this i s achieved by using the binary-coded-decimal (BCD) outputs of a d i g i t a l voltmeter. Figure 3 shows the 27 lines that constitute the multiplexor bus; 16 lines are reserved for data input and output which i s matched to the 8-bit byte.  The 8 control  l i n e s , with one exception, are used to enable data onto the data l i n e s .  The control designated ACKO, together with the  attention l i n e (ATNO) and the system clear l i n e (SCLRO), are associated with the processor interrupt f a c i l i t y which i s an optional feature of every device c o n t r o l l e r .  The synchronize  l i n e (SYNO) i s used to n o t i f y the processor when a signal on one of the control lines i s accepted by a device c o n t r o l l e r . A t y p i c a l sequence of operations to service the mass spectrometer over the multiplexor channel would be: 1.  A pulse from the d i g i t a l voltmeter, signifying that  data i s available at the mass spectrometer, causes a signal to be sent along the attention l i n e (ATNO) which interrupts the processor.  The processor acknowledges the interrupt and sends  a signal over the ACKO l i n e which i n i t i a t e s a hardware scan cycle to determine which device caused the ATNO s i g n a l .  The  mass spectrometer automatically returns i t s device number to the processor over the data request lines (DRL's).  The processor  i s now ready to service the mass spectrometer. 2.  The mass spectrometer i s addressed by the processor  over the 8 data available lines (DAL's). on the bus to a l l device c o n t r o l l e r s .  This address appears  8 DAL s 1  -  8 DRL's •—  MULTIPLEXOR BUS  ^  < EH  TACKO  SYNO  o  RACKO  o o  TACKO  ACKO ^  RACKO  PROCESSOR  •  8 CL's  INTERDATA  ATNO V  INIT.  SCLRO  '  INI  FAC1 M.S.I  FIGURE 3.  IN  FAC12-2  r  M.S. 2  THE MULTIPLEXOR CHANNEL  [NT!  FACE - 3 M.S.3  3.  The p r o c e s s o r then a c t i v a t e s the address  control  l i n e which s i g n i f i e s t h a t the DAL's now p r o v i d e an address (as  opposed t o d a t a ) .  4.  The mass spectrometer  i n t e r f a c e decodes i t s a d d r e s s ,  s e t s a f l i p - f l o p memory, and sends a s i g n a l back t o the p r o c e s s o r along the SYNO l i n e . addressed  until  another  a system c l e a r s i g n a l  The mass spectrometer  remains  d e v i c e c o n t r o l l e r i s addressed  or u n t i l  (SCLRO) i s r e c e i v e d .  5.  The p r o c e s s o r p l a c e s an "output command" on the DAL's.  6.  The p r o c e s s o r then a c t i v a t e s the command c o n t r o l  t h i s causes of  the data from  to  ( f o r i n s t a n c e ) one p a r t i c u l a r decade  the d i g i t a l v o l t m e t e r , s p e c i f i e d by the output  be made a v a i l a b l e .  command, to  A SYNO s i g n a l i s sent back t o the p r o c e s s o r  i n d i c a t e the command has been s t o r e d i n the d e v i c e  7.  line;  The mass spectrometer  i s again addressed  controller.  by the  proc-  e s s o r , as d e s c r i b e d i n steps 2, 3 and 4. 8.  The p r o c e s s o r then a c t i v a t e s the data r e q u e s t (DR)  c o n t r o l l i n e which enables the byte o f d a t a , made a v a i l a b l e i n step 6, from the d i g i t a l v o l t m e t e r to the p r o c e s s o r , along the DRL's.  A synchronize s i g n a l  (SYNO) i s generated  t h a t the data has a r r i v e d at the p r o c e s s o r .  to indicate  12.  2.3  Programming the I n t e r d a t a Model 4 The  I n t e r d a t a Model 4 computer possesses  of 75 b a s i c i n s t r u c t i o n s which can manipulate  a repertoire  data between core  memory, 16 g e n e r a l r e g i s t e r s , and up t o 256 e x t e r n a l d e v i c e s . In a d d i t i o n , the I n t e r d a t a system a l s o p r o v i d e s f o r the d i r e c t t r a n s f e r o f a b l o c k o f data between core memory and a p e r i p h e r a l d e v i c e under c o n t r o l o f an o p t i o n a l s e l e c t o r c h a n n e l . i n i t i a t e d by the p r o c e s s o r , t h i s d i r e c t v i s i b l y without  Once  t r a n s f e r takes p l a c e i n -  i n t e r r u p t i o n t o normal p r o c e s s i n g .  Data o f three d i f f e r e n t word l e n g t h s ; the 8 - b i t b y t e , 16-bit halfword, instruction set.  and 3 2 - b i t f u l l w o r d , can be manipulated  by the  In the I n t e r d a t a system hexadecimal n o t a t i o n  (base 16) i s used t o express  b i n a r y i n f o r m a t i o n , so t h a t , f o r  example, a byte o f data can be r e p r e s e n t e d by two hexadecimal digits. Three i n s t r u c t i o n formats data system: r e g i s t e r t o r e g i s t e r  are a v a i l a b l e i n the I n t e r -  (RR), r e g i s t e r to indexed  memory (RX), and r e g i s t e r t o storage 1 6 - b i t g e n e r a l r e g i s t e r s , numbered Oto f u n c t i o n as accumulators l o g i c a l operations.  (RS). A t o t a l o f s i x t e e n F i n hexadecimal n o t a t i o n ,  or index r e g i s t e r s  i n a r i t h m e t i c and  In a l l t h r e e i n s t r u c t i o n formats,  bits  0-7 s p e c i f y the machine o p e r a t i o n to be performed  ( t h 8 - b i t OP  code); b i t s 8-11 s p e c i f y the address  operand,  which i s n o r m a l l y address  a general r e g i s t e r .  o f the f i r s t  In the RR format the  o f the second operand i s s p e c i f i e d by b i t s 12-15 and i s  always a g e n e r a l r e g i s t e r . bits  12-15  In the RX  always s p e c i f y the address  whose content  instruction of a general  i s used as an index v a l u e .  bits  ( b i t s 16-31) s p e c i f y a memory address  and,  i n the case o f the RS  format,  an  formats,  The  register  remaining  i n the RX  16  format,  i n t e g e r v a l u e f o r use  as an immediate operand. A summary o f the I n t e r d a t a Model 4 programming  instruc-  t i o n s i s given i n Appendix I I I . The  information necessary  f o r program e x e c u t i o n i s  c o n t a i n e d i n the 3 2 - b i t program s t a t u s word of  the PSW  12-15  (PSW).  Bits  0-11  d e f i n e the s t a t u s o f the c u r r e n t user program; b i t s  c o n s t i t u t e the 4 - b i t c o n d i t i o n code  (CC) which i s s e t  a f t e r e x e c u t i o n o f i n p u t / o u t p u t , l o g i c a l , s h i f t or a r i t h m e t i c instructions. be executed field  The memory address  o f the next  instruction  i s s p e c i f i e d by the 1 6 - b i t i n s t r u c t i o n  ( b i t s 16-31  o f the  to  address  PSW).  In i n s t a n c e s o f machine m a l f u n c t i o n s , d i v i d e f a u l t s , illegal  i n s t r u c t i o n s , and e x t e r n a l d e v i c e s e r v i c e r e q u e s t s ,  system i n t e r r u p t s are generated. the c u r r e n t PSW,  When an i n t e r r u p t  which d e f i n e s the p r e s e n t o p e r a t i n g s t a t u s o f  the p r o c e s s o r , i s p l a c e d i n a r e s e r v e d storage area PSW)  and  a new  i s recognised,  PSW  (the o l d  r e - d e f i n e s the s t a t u s o f the machine.  On com-  p l e t i o n o f the i n t e r r u p t s e r v i c e sub-program the p r e v i o u s machine s t a t u s , s t o r e d i n the o l d PSW, Input/output  i s restored.  data t r a n s f e r i n the I n t e r d a t a system can  be e i t h e r program c o n t r o l l e d or i n t e r r u p t c o n t r o l l e d .  The  former  method i n t e r r o g a t e s  the d e v i c e t o a s c e r t a i n  t r a n s f e r d a t a , and waits i f n e c e s s a r y u n t i l  i f i t i s ready to t r a n s f e r can o c c u r .  The i n t e r r u p t method allows the d e v i c e t o demand s e r v i c e it  i s ready  f o r the t r a n s f e r o f d a t a .  when  T h i s l a t t e r method i s  the one employed f o r the mass spectrometer  interface.  CHAPTER 3  THE  3.1  INTERFACE HARDWARE DESIGN  Introduction. The  c o n s t r u c t i o n o f a s u c c e s s f u l computer i n t e r f a c e  i n v o l v e s the d e s i g n  of s u i t a b l e l o g i c c i r c u i t r y which w i l l  enable the computer to communicate with the p a r t i c u l a r pheral  peri-  device. The  hardware design  i s evolved  l o g i c elements a v a i l a b l e , namely flops.  gates,  u s i n g the  i n v e r t e r s and  F i g u r e 4 summarises the most commonly used  elements t o g e t h e r with g e n e r a l , gates computer and  standard  logic  their respective truth tables.  are used to d i r e c t the s i g n a l s to and  flip-flops  flip-  In from  the  are used to s t o r e i n f o r m a t i o n , a c t i n g  as o n e - b i t memories. Logic c i r c u i t analog  circuit  employed, and o f these  designs  d e s i g n i s i n general e a s i e r than most because o n l y two  voltage  d u r a t i o n of a few o f both types peripheral  are  the o n l y major concern i s the d u r a t i o n and  voltage s i g n a l s .  the steady  voltage l e v e l s  There are two  l e v e l and  classes of  the p u l s e , the  tens of nanoseconds  signal,  l a t t e r having  (typically).  The  o f s i g n a l are c o n t r o l l e d by the p r o c e s s o r  device.  timing  a  timing and  the  16.  TRUTH TABLES A  B  f  INVERTER &MC834P)  0 1  AND GATE &MC1806P)  0 0 1 1  0 1 0 1  0 0 0 1  NAND GATE &MC849P)  0 0 1 1  0 1 0 1  1 1 1 0  0 0 1 1  0 1 0 1  0 1 1 1  0 0 1 1  0 1 0 1  1 0 0 0  S-n,  R* C>  0 0 1 1  0 1 0 1  0  0  OR GATE &MC1809P)  NOR GATE  CLOCKED FLIP-FLOP (MC845P)  J-K FLIPFLOP &MC855P)  FIGURE 4.  A_ B  A_ B  C_  J C K  t  Q  0 1 I  1 0  1 0 1  0 1  Cv 0 1  BASIC LOGIC FUNCTIONS $ TRUTH TABLES  Once the interface logic c i r c u i t r y has been designed, by suitably matching the computer and peripheral device speci f i c a t i o n s to perform the required functions, i t i s then only necessary to select appropriate integrated c i r c u i t logic packages (chips) to perform the required task consistently. When choosing logic packages there i s normally a choice between five different logic families namely, r e s i s t o r transistor logic (RTL), diode-transistor logic (DTL) , t r a n s i s t o r transistor logic (TTL), high-threshold logic (HTL), and emittercoupled logic (ECL); Table II compares the 2-input NAND function for the five logic families.  ECL i s a non-saturating form of  logic which eliminates transistor storage time as a speed l i m i t i n g c h a r a c t e r i s t i c , i t i s used where extremely high speed operation i s required.  HTL was developed for applications such  as i n industry requiring a higher degree of inherent e l e c t r i c a l noise immunity than i s available with the more standard integrated c i r c u i t logic families.  Disadvantages of HTL are a r e l a t i v e l y  high supply voltage (15±1 v o l t s ) and slow speed. medium speed, high noise-immunity  TTL i s a  family of saturating integrated  logic c i r c u i t s , i t i s presently the most commonly employed logic family.  DTL offers moderate speed and good noise immunity, i t i s  somewhat i n f e r i o r to TTL and used to be less expensive.  RTL i s  slow, has poor noise immunity and a large power d i s s i p a t i o n , i t i s no longer used commercially i n high quality d i g i t a l electronics.  TABLE I I  SPECIFICATIONS OF QUAD 2-INPUT NAND FUNCTION FOR THE FIVE LOGIC FAMILIES  LOGIC FAMILY  TYPICAL MOTOROLA NUMBER  SUPPLY VOLTAGE VOLTS  RTL  MC9714P  +3±.3  DTL  MC849P  +5±l/2  TTL  MC7400P  HTL  ECL  OUTPUT LOADING FACTOR  RELATIVE NOISE IMMUNITY  PROPAGATION DELAY ns TYPICAL  TOTAL POWER DISSIPATION mW TYPICAL/PKG.  APPROX. COST/ PKG.  WORST  55  145  $1.55  7  MODERATE  25  66  $1.65  +5±l/2  10  GOOD  13  40  $1.29  MC672P  +15±1  10  BEST  110  114  $1.40  MC1048P  -5.2±l/2  25  BAD  130  $3.90  oo  Diode-transistor logic was chosen for the mass spectrometer interface because i t s specifications are more than adequate for the r e l a t i v e l y slow speeds involved and because, at the time of purchase, i t was s l i g h t l y less expensive than the equivalent transistor - t r a n s i s t o r l o g i c , i t i s also the logic family most used i n the Interdata Model 4 Processor.  Where a p a r t i c u l a r logic function was not a v a i l -  able i n DTL then the appropriate TTL function was employed. An aggravating problem often encountered with d i g i t a l logic c i r c u i t r y i s e l e c t r i c a l noise pickup, e i t h e r , from adjacent lines running i n close proximity ( i n t e r l i n e crosstalk) or, from other sources.  The best way of eliminating i t i s to use  high-threshold logic (HTL) which operates at a 7.5 volt threshold level.  This logic family i s somewhat inconvenient to use, un-  fortunately, since a separate 15 volt regulated power supply i s required together with HTL/DTL l e v e l converters on a l l lines to and from the interface. slower than DTL.  In addition, HTL i s about five times  Using diode-transistor l o g i c , with careful  c i r c u i t design, i t i s generally possible to keep noise pickup at a negligible level.  Where a c i r c u i t element i s required to  drive a long l i n e , for instance between the processor and a peripheral device, a power gate and appropriate pull-up r e s i s t o r are always used.  This helps to provide good noise immunity,  primarily by lowering the impedance l e v e l of the l i n e s .  In addi-  t i o n , a l l long lines are made f a l s e - a c t i v e , i . e . , a l i n e i s active  20.  when i t i s at ground p o t e n t i a l  (zero v o l t s ) , to f u r t h e r  reduce  the p o s s i b i l i t y o f n o i s e p i c k u p . The some d e t a i l .  f o l l o w i n g pages d e s c r i b e the l o g i c c i r c u i t r y i n I t has been found c o n v e n i e n t , f o r c i r c u i t d e s c r i p -  t i o n , t o d i v i d e the i n t e r f a c e i n t o f i v e s e c t i o n s , namely, d e v i c e a d d r e s s i n g , data and s t a t u s i n p u t , data and command i n t e r r u p t c o n t r o l , and r e a d / w r i t e sequencing  3.2  Device The  output,  circuitry.  Addressing  I n t e r d a t a d e v i c e a d d r e s s i n g l o g i c diagram i s  shown i n F i g u r e 5. The  mass spectrometer  address  i n t o the d e v i c e number s e l e c t i o n board. on the data a v a i l a b l e l i n e s d e v i c e output line  (DALOO  (DDO) goes low.  (hexadecimal  D) i s w i r e d  When t h i s address  appears  through DAL07) the decoded  A s i g n a l on the address  (ADRSO), i n c o n j u n c t i o n w i t h DDO, s e t s the address  f l o p so t h a t i t s output (DENB1) i s made h i g h .  control flip-  During the presence  of ADRS1, a s y n c h r o n i z e s i g n a l i s r e t u r n e d t o the p r o c e s s o r v i a the address  synchronize l i n e  seconds i s produced (SYNO).  the  A d e l a y o f about 200 nano-  by c a p a c i t o r C l on the synchronize  T h i s prevents the p r o c e s s o r from  l i n e b e f o r e the address able l i n e  (ADSYO).  line  lowering the ADRSO  f l i p - f l o p has been s e t .  The d e v i c e en-  (DENB1) gates a l l other i n p u t / o u t p u t c o n t r o l l i n e s t o  interface. When the address  o f another d e v i c e appears  on the data  a v a i l a b l e l i n e s , DDI goes low, c a u s i n g ADRS1 t o r e s e t the address  ATS Y N O  ATSYN1  DEVICE NUMBER SELECTION  0  0  GO  -DAO  DALO 0[> -O  -D>  -o  -i>  4>  (r-  o  o  -o  -0  0G7  -0A7  70DDO  DENB1  DDI  o  ADRSO  S  AP_RS_1~  -0  Q  T R ADDRESS FLIP-FLIP  :470pF  ADSYO  SYNO  ATSYNO  <r  CDSYO  ;470pF  Figure 5.  Device  -DRSYO  Addressing,  Logic  Diagram  SRSYO —DASYO  f l i p - f l o p , and d i s a b l e the mass spectrometer The  interface.  e i g h t NAND g a t e s , GO through G7, t o g e t h e r w i t h  the l i n e s ATSYNO and ATSYN1, are p a r t o f the i n t e r r u p t  control  c i r c u i t r y d e s c r i b e d i n s e c t i o n 3.5  3.3  Data and Status Input F i g u r e 6 shows the I n t e r d a t a i n p u t g a t i n g l o g i c  diagrams. When the mass spectrometer i s addressed, DENB1 i s h i g h , e n a b l i n g the data r e q u e s t control line.  (DRO) o r status  r e q u e s t (SRO)  The data o r s t a t u s byte i s thus enabled  the d a t a request l i n e s  (DRLOO through DRL07).  onto  A r e t u r n syn-  c h r o n i z e s i g n a l , DRSYO o r SRSYO, i s a u t o m a t i c a l l y generated when e i t h e r o f the c o n t r o l The  l i n e s i s enabled.  l i n e s AO through A7 connect  t o the e i g h t g a t e s ,  GO through G7, shown i n F i g u r e 5 and form p a r t o f the i n t e r r u p t c o n t r o l l e r d e s c r i b e d i n s e c t i o n 3.5.  3.4  Data and Command Output The c i r c u i t  shown i n F i g u r e 7 i s used t o c o n t r o l the  flow o f data and commands from the p r o c e s s o r . When the mass spectrometer i s addressed, DENB1 i s h i g h , e n a b l i n g the data a v a i l a b l e line.  (DAO) o r command (CMDO) c o n t r o l  DAO o r CMDO, i n t u r n , enable the data o r command byte  onto the data a v a i l a b l e l i n e s  (DALOPO through DAL0P7).  t i o n , c o n t r o l p u l s e s are sent t o the r e a d / w r i t e l o g i c  In a d d i ( F i g u r e 9)  23. DENB1  +5v  SRSYO  D  SRO  0—  +5v  DRSYO  1470.0. DRO  0—  SIIMOP DRLO  oo  a  —Oo  AO  DINOP  p  —<]o  -0  Q  <r  9-  -0  -0 <r  <3  ®  A  »  •0 -0  <r  T A  •0 -0 4  -0  -<3 <&  A  ^  -0 -0  <r  -0  A  -07  7<r  Figure 6 .  A7  —© A Data and Status Input,  & Logic  -07  Diagram  Figure7 Data and C o m m a n d Output, Logic  Diagram  via  the DAGOP or CMGOP l i n e .  i s shortened,  The d u r a t i o n o f these  pulses  from about 800 ns t o about 400 ns, by the use  o f a one-shot m u l t i v i b r a t o r i n each l i n e ; the c o n t r o l p u l s e s  are removed b e f o r e  t h i s ensures t h a t  the data  disappears  from the DALOP l i n e s .  The l i n e s DASYO and CDSYO r e t u r n the  r e s p e c t i v e synchronize  s i g n a l s to the p r o c e s s o r .  The  data a v a i l a b l e and command c o n t r o l l i n e s are  OR ed so t h a t there cannot be any data o r commands on the DALOP l i n e s except when one o f the two c o n t r o l l i n e s Thus t h i s  i s active.  OR gate e l i m i n a t e s extraneous n o i s e on the data  t r a n s m i s s i o n c a b l e , an advantage when s e v e r a l i n t e r f a c e c a b l e s are run i n c l o s e  3.5  proximity.  Interrupt The  Control  logic circuit  f o r the I n t e r d a t a i n t e r r u p t c o n t r o l -  l e r i s shown i n F i g u r e 8. The  d e t a i l e d operation of t h i s c i r c u i t  i s described  i n the Interdata"Systems I n t e r f a c e Manual" and o n l y a b r i e f e x p l a n a t i o n w i l l be given The to  here.  enable/disable  switch  i s s e t i n the enable p o s i t i o n  a c t i v a t e the i n t e r r u p t c o n t r o l l e r .  a v a i l a b l e a t the d i g i t a l v o l t m e t e r  When a byte  o f data i s  a data ready p u l s e  i s gener-  ated which causes the queue f l i p - f l o p t o be d i r e c t s e t . output to  The  from the queue f l o p - f l o p sends an a t t e n t i o n s i g n a l (ATNO)  the p r o c e s s o r  v i a G12.  The p r o c e s s o r  responds by r e t u r n i n g  26. TACKO +5v4 |  ATIMO  RACKO  .+5v  V  47Cvn|  P G13  G12  +5v  470pF  *  DATA - 0 READY  * Q  J T>  QUEUE FLIP-FLOP  K—  SCLROA <j  +5v<  +5v  >470.n.  d*70ii  0-  ATSYNO  Gil  0  ATSYN1  0  &  470pF  C2 I  Figure 8 .  Interrupt  Control,  Logic  Diagram  27.  a r e c e i v e acknowledge s i g n a l gate G8 d i s a b l e s G13 signal and G10  (RACKO) to the c o n t r o l l e r .  The  and prevents the t r a n s m i t acknowledge  (TACKO) from being sent to the next d e v i c e .  Gates  G9  generate a t t e n t i o n s y n c h r o n i z e (ATSYNO) which sends  synchronize s i g n a l  (SYNO) to the p r o c e s s o r as w e l l as c a u s i n g  the mass spectrometer address to appear through G7  a  (see F i g u r e 5 ) .  on the i n p u t s of GO  T h i s address i s then enabled onto the  data r e q u e s t l i n e s by the ATSYNI output from G i l .  On  receiving  the SYNO s i g n a l , the p r o c e s s o r r a i s e s RACKO, c a u s i n g the output of  G i l t o drop and the queue f l i p - f l o p  to r e s e t .  I f the p r o c e s s o r i s busy s e r v i c i n g another d e v i c e i n t e r r u p t , when a data ready p u l s e i s generated, RACKO i s low and the mass spectrometer i n t e r r u p t i s d i s a b l e d .  However, t h i s  l a t t e r i n t e r r u p t i s s t o r e d i n the queue f l i p - f l o p  and i s  s e r v i c e d immediately  a f t e r the p r e v i o u s i n t e r r u p t has been  serviced. A push-button initialize  s w i t c h s i t u a t e d at the p r o c e s s o r (the  switch) i s connected v i a the system c l e a r  line  (SCLRO) t o each i n t e r r u p t c o n t r o l l e r such t h a t a l l queue  flip-  f l o p s can be d i r e c t r e s e t s i m u l t a n e o u s l y . The  i n t e r r u p t acknowledge c o n t r o l l i n e  (ACKO) shown  i n F i g u r e 3 i s d i v i d e d up i n t o a s e r i e s o f s h o r t l i n e s to form the d a i s y - c h a i n p r i o r i t y  system.  C l e a r l y the acknowledge s i g n a l  must pass through every i n t e r f a c e equipped w i t h an c o n t r o l l e r , and the d e v i c e s i t u a t e d c l o s e s t  interrupt  ( e l e c t r i c a l l y ) to  the p r o c e s s o r , along the d a i s y - c h a i n , has h i g h e s t p r i o r i t y .  28.  3.6  Read/Write The  Sequencing  logic circuit  shown i n F i g u r e 9 i s used t o c o n t r o l  the sequencing o f the read and w r i t e o p e r a t i o n s c a l l e d  f o r by  the computer program. Data and command bytes from the p r o c e s s o r a r r i v e along the DALOP l i n e s and are f e d to the output command and d i s p l a y l o g i c  (0C) memory  (Figure 15) v i a the f o u r DALIP l i n e s .  Three  o f the outputs from the 0C memory are used t o d r i v e a l - o f - 8 decoder which p r o v i d e s the sequencing s i g n a l s f o r both read and write operations.  The remaining output i s used to p r o v i d e a  read o r w r i t e enable s i g n a l t o a s e r i e s o f AND g a t e s . Both the data bytes r e c e i v e d from the d i g i t a l v o l t m e t e r and the data bytes t o be w r i t t e n upon the d i s p l a y have t o be sequenced  i n a p a r t i c u l a r order.  T h i s i s accomplished p a r t l y by  the software and p a r t l y by the sequencing The logic  3.6.1  logic.  e x t e r n a l c o n n e c t i o n s t o the r e a d - w r i t e sequencing  ( i n t e r f a c e s e c t i o n 2) are shown i n F i g u r e 10.  Read O p e r a t i o n Binary-coded-decimal  (BCD) i n f o r m a t i o n i s a v a i l a b l e  on f o u r l i n e s from each decade o f the d i g i t a l v o l t m e t e r . d a t a , t o g e t h e r w i t h the overrange  This  d i g i t , i s gated onto the  l i n e s DIN0P4 through DIN0P7; the l i n e s DINOP0 through DIN0P3 being unused.  Additional  i n f o r m a t i o n p e r t a i n i n g t o shunt number,  scan d i r e c t i o n and d i s p l a y f u n c t i o n s w i t c h p o s i t i o n , are a l s o gated onto the DINOP l i n e s .  p  FIGURE 9.  L>n  COMPUTER/MASS SPECTROMETER INTERFACE READ/WRITE LOGIC  DIGITAL VOLTMETER 17 LINES  RANGED TO SHUNT 'SELECT SWITCH  4DAL0P5 6  : :  7  :  DAGOP: CMGor: 4 5 6 7  SHUNT NUMBER  INTERFACE SECTION-2 READ/WRITE SEQUENCING LOGIC  UP  SCAN DIRECTION  STOP.  ODOWN 1  i  <D.U.  8 LINES  FUNCTION SELECT SWITCH  SEP.  4 LINES  >*<REJ, AUTO  14 LINES MAN,  DISPLAY  FIGURE 10.  ,GANGED TO SCAN /DIRECTION SWITCH  SCAN RATE CONTROL  2 LINES  EXTERNAL CONNECTIONS  A  SCAN  V  DRIVE  TO READ/WRITE  SEQUENCING LOGIC  ~  SCAN STOP UP DOWN II SEP. it R EJ. II  Figure 11 shows a t y p i c a l sequence of instructions necessary to read the d i g i t a l voltmeter, shunt number, scan d i r e c t i o n , and display function switch p o s i t i o n .  It is  assumed here that the d i g i t a l voltmeter has generated an interrupt and the processor i s now ready to service the mass spectrometer.  An "output command (0C)" i s sent from the  processor, arrives at theflCmemory (Figure 9), and i s promptly stored on" receipt of a command strobe pulse (CMGOP). This f i r s t 0C contains the coded information requesting that the overrange d i g i t of the d i g i t a l voltmeter be placed on the DINOP l i n e s .  The next i n s t r u c t i o n i s "read data (RD)" which  causes the data on the DINOP lines to be read into a specified location i n core memory. The "add halfword register (AHR)", "compare l o g i c a l halfword immediate (CLHI)", and "branch on low (BL)", instructions cause the 0C index register to be r e p e t i t i v e l y incremented by one u n t i l a l l available information has been read, one byte at a time, into separate locations i n core memory. 3.6.2  Write Operation The sequence of instructions necessary to write (out-  put) data from core memory (Figure 12) resemble those used to read (input) data from the mass spectrometer (Figure 11) . The "output command (0C)" sequences the output bytes i n a similar manner to that described i n Section 3.6.1, however b i t 4 of the  OOOOR 0002R 0004R 0006R 0008R OOIOR 0012R  0809 OAOB OCOD OEOF  RCMD  RDATA  0755 C820 0001 0 0 1 6R C 8 3 0 OOOD 001AR DE35 OOOOR 001ER DB35 0008R 0022R 0A52 0024R C550 0008 0026R 4280 001AR  0012R 0 0 1 6R 001AR 0 0 1 ER 0020R 0024R  0001 0203 0400  RSTART  FIGURE  WCMD  CONSTANTS  D E F I N E STORAGE ZERO REG#5 L O A D 1 INTO REG#2 LOAD  13 INTO REG# 3  OC  3>RCMD<5)  OUTPUT  RD  3.» RDATAC 5 >  R E A D ONE B Y T E DATA  AHR CLHI  5* 2 5*8  I N C R E M E N T REG#5 BY 1 CONTENTS REG#5<8?  BL  RSTART  Y E S ; B R A N C H TO R S T A R T  DC DC DC DS XHR LHI LHI  WSTART  OC WD  12.  DEFINE  COMMANDC R E A D )  READ SEQUENCING INSTRUCTIONS  WDATA 0755 C820 0001 C830 OOOD DE3 5 OOOOR DA35 0006R 0A52 C550 0005 4280 0 0 1 6R  X'0809' X'OAOB' X'OCOD' X'OEOF' 8 5, 5 2, H' 1 '  LHI  FIGURE 11.  OOOOR 0002R 0004R 0006R OOOCR OOOER  DC DC DC DC DS XHR LHI  X'OOOl • X '0203 ' X '0400 * 6 5> 5 2#H'1 ' 3*H"1 3 ' 3*WCMD(5)  AHR CLHI  3>WDATAC5) 5* 2 5> 5  BL  WSTART  DEFINE  CONSTANTS  D E F I N E STORAGE ZERO REG#5 L O A D 1 INTO REG#2 LOAD  13 INTO  OUTPUT  REG#3  COMMANDCWRITE)  W R I T E ONE B Y T E DATA I N C R E M E N T REG#5 BY 1 CONTENTS REG#5<5? Y E S ; B R A N C H TO  WRITE SEQUENCING INSTRUCTIONS  WSTART  0C  i s now  a zero causing the w r i t e l i n e  When a " w r i t e d a t a (WD)"  t o be made a c t i v e .  i n s t r u c t i o n i s executed, a byte o f  data i s f e t c h e d from a s p e c i f i e d l o c a t i o n i n core memory and p l a c e d on the DAL's.  A p u l s e on the DAGOP c o n t r o l  line  s t r o b e s t h i s data byte i n t o one decade o f the d i s p l a y d e s i g nated by the p r e v i o u s The  0C.  l o c a t i o n of the decimal p o i n t on the d i s p l a y i s  c o n t r o l l e d by a separate memory and decoder,  and can be  dated when r e q u i r e d by a s u i t a b l y coded 0C and WD S i m i l a r l y the mass spectrometer magnetic v a r i e d u s i n g another memory. memory i s connected  via  instruction.  scan r a t e can  Each output of t h i s  be  latter  to a simple t r a n s i s t o r s w i t c h i n g c i r c u i t  which c o n t r o l s the frequency of a u n i j u n c t i o n oscillator.  up-  T h i s , i n t u r n , determines  transistor  the magnetic  a s t e p p i n g motor and p o t e n t i o m e t e r .  The  scan r a t e  complete  scan  d r i v e c i r c u i t , designed by R. D. R u s s e l l , i s given i n Appendix II.  In the p r e s e n t system  t h e r e are f o u r p o s s i b l e scan speeds  which are c o n s i d e r e d ample f o r the programmed c o n t r o l  envisaged  A programming guide f o r the mass spectrometer face i s given i n Appendix  3.7  IV.  The A n a l o g - T o - D i g i t a l C o n v e r t e r A Model 344-2 d i g i t a l v o l t m e t e r  by the Data Technology digital  inter-  (A/D)  (DVM)  manufactured  C o r p o r a t i o n i s used as an a n a l o g - t o -  c o n v e r t e r i n the data a c q u i s i t i o n system.  This  34.  instrument, A/D  utilizes  the dual s l o p e i n t e g r a t i o n technique f o r  conversion. F i g u r e 13 shows a b l o c k diagram o f the DVM and  F i g u r e 14 i l l u s t r a t e s The  analog  some t y p i c a l dual slope waveforms. v o l t a g e output  from the mass spectrometer  measuring system i s a p p l i e d t o the input a m p l i f i e r o f the DVM. A pulse  from the r e s e t o s c i l l a t o r  (frequency:  5Hz) i n i t i a t e s  a 10,000 count such t h a t the i n p u t s i g n a l i s i n t e g r a t e d f o r a p e r i o d o f 50ms. oscillator  T h i s i n t e g r a t i o n time i s c o n t r o l l e d by a200KHz  (clock).  The i n t e g r a t i n g c a p a c i t o r ( C l ) i s d i s -  charged u n t i l the 10,000 count i s completed ing  a voltage  Upon r e a c h i n g  full  s c a l e the i n p u t c u r r e n t  and a constant  The  c a p a c i t o r i s then charged a t a constant continues  c u r r e n t source  to run.  (Ijjyj)  ( I ^ p ) i s switched  t r i g g e r s a one-shot p u l s e  are used to p r o v i d e interface.  and d i s a b l e s  The  The BCD outputs  the d i g i t a l  output  (data ready)  the q u a t c h - l a t c h memories t o accept  numbers i n t o s t o r a g e .  (ZD)  (N), accumulated by the  i s p r o p o r t i o n a l t o the i n p u t v o l t a g e .  which enables  the capac-  (15 v o l t s ) , a zero d e t e c t  The number o f counts  of the ZD f l i p - f l o p  to C l .  r a t e w h i l e the  p u l s e i s generated which r e s e t s the ZD f l i p - f l o p  c ou nt er ,  signal.  i s switched  When the v o l t a g e across  i t o r reaches the s t a r t v o l t a g e  the c l o c k .  s c a l e ) , leav-  on C l which i s p r o p o r t i o n a l t o the i n p u t  off  counter  (full  the new  BCD  from these memories  information  f o r the computer  +200V  ^POS  NECi)  5 JK F/F  (  "1000" ~  ^  "100" ~ ~ ^ )  ^  "10"  ^  "1"  """^  DECODER DRIVER  r  QUAD LATCH  8  JK F/F  4  2  1  4  2  1  COUNTER  FULL SCALE  VlN  ("  200 kHr OSC  START-FULL SCALE FLIP-FLOP  ZERO  DETECT(ZDI  RESET OSC  ONE SHOT  EXT S T A R T  DATA READY  UN QUAD LATCH  FIGURE 13.  ANALOG-TO-DIGITAL CONVERTER BLOCK DIAGRAM (Reproduced, by p e r m i s s i o n , from Data Technology Corp., Manual#18915-10)  RESET  tfg  to 1  1  tzo { I  ^  50ms  START FULL SCALE FLIP-FLOP  ^  c  200KHz CLOCK  ZERO DETECT  DATA READY FIGURE 14.  DUAL SLOPE WAVEFORMS-FOR DIGITAL VOLTMETER  An important f e a t u r e  o f the dual slope  technique i s  t h a t the accuracy o f the A/D c o n v e r s i o n i s n o t dependent on the  drift  o f the 200KHz o s c i l l a t o r .  Since the 10,000 count  remains c o n s t a n t , the i n t e g r a t i n g time v a r i e s w i t h any o s c i l l a t o r d r i f t  such t h a t the t o t a l count, N, remains  constant f o r a g i v e n input The  i n accordance  voltage.  Model 344-2 DVM has a f u l l  scale voltage  of 0-1.0000 v o l t s w i t h a 40% overrange c a p a b i l i t y .  range  The manu-  f a c t u r e r s quoted a c c u r a c y i s ±(.011 r e a d i n g + .0001) v o l t s .  3.8  The Numerical The  n u m e r i c a l output d i s p l a y  eter interface consists Each module c o n s i s t s input The  data  Display f o r the mass spectrom-  o f 5 Datecon DS-103 d i s p l a y modules.  o f a q u a d - l a t c h memory which s t o r e s the  ( i n BCD format) on a p p l i c a t i o n o f a s t r o b e  pulse.  output from the memory i s f e d to a BCD-to-Decimal decoder  which d r i v e s  a cold-cathode decade d i s p l a y tube.  tube i n c o r p o r a t e s  Each  display  a decimal p o i n t which can be c o n t r o l l e d by  a separate q u a d - l a t c h memory and decoder  (Figure  9).  Power  requirements, i n a d d i t i o n t o the +5 v o l t s l o g i c s u p p l y , are a +200 v o l t s supply f o r the d i s p l a y tube anodes. Figure  3.9  15 shows the complete d i s p l a y l o g i c  Construction The  circuit.  o f the I n t e r f a c e  i n t e r f a c e was c o n s t r u c t e d  i n two s e c t i o n s  to t r y  38. DAL IP  COLD-CATHODE +200V DECADE DISPLAY TUBE 0 A  8  2  OMEMORY  1 2 4 8  BCD/DEC DECODER DRIVER  1 OMEMORY  BCD/DEC DECODER DRIVER  2 OBCD/DEC MEMORY  DECODER DRIVER  3 t>BCD/DEC MEMORY  DECODER DRIVER  4 o-  MEMORY  A A A AA DECIMAL POINTS  FIGURE 15.  THE NUMERICAL DISPLAY  39.  and minimize  the number of communication l i n e s between the  computer and mass spectrometer. address  l o g i c , the data and s t a t u s i n p u t l o g i c , the data  and command output on two  S e c t i o n 1 c o n s i s t s of the  l o g i c , and the i n t e r r u p t c i r c u i t r y  built  d o u b l e - s i d e d p r i n t e d c i r c u i t boards which s l i d e  a rack s i t u a t e d i n s i d e the computer c a b i n e t . c o n t a i n s the r e a d / w r i t e l o g i c c i r c u i t r y  into  Section 2  illustrated  9; the p r o t o t y p e u n i t c o n s t r u c t e d by the w r i t e r was  i n Figure built  on  6 s i n g l e - s i d e d p r i n t e d c i r c u i t boards which c o u l d communicate w i t h each other through  22 p i n c o n n e c t o r s .  The  6 printed  c i r c u i t boards, n u m e r i c a l d i s p l a y , d i g i t a l v o l t m e t e r ,  and  power s u p p l y are mounted on an aluminum c h a s s i s which  fits  i n t o the mass spectrometer  console.  An aluminum f r o n t  panel  i n c o r p o r a t e s the d i s p l a y and v o l t m e t e r b e z e l s and a l l the necessary  switches. The  used  integrated c i r c u i t  ( i . e . ) l o g i c packages  i n the c o n s t r u c t i o n o f the i n t e r f a c e are mostly  (chips)  Motorola  DTL p l a s t i c types w i t h the e x c e p t i o n o f the complex f u n c t i o n s (decoders  and quad l a t c h memories) which are o f the TTL f a m i l y  (see T a b l e I I I ) .  Each 14 or 16 p i n p l a s t i c package c o n t a i n s  from 1 to 6 l o g i c elements depending upon the p a r t i c u l a r function desired. spectrometer  logic  A l l the i . e . packages employed i n the mass  i n t e r f a c e were designed  v o l t s r e g u l a t e d power supply The power supply  f o r o p e r a t i o n from a  5±1/2  (±5%).  (PS-200) i n s e c t i o n 2 s u p p l i e s the  200 v o l t s f o r the cold-cathode  decade d i s p l a y tubes  and a  s t a b i l i z e d 5 v o l t s f o r the r e a d / w r i t e l o g i c c i r c u i t r y . packages i n s e c t i o n 1 u t i l i z e  The i . e .  the I n t e r d a t a P r o c e s s o r 5 v o l t  TABLE I I I  INTEGRATED CIRCUIT PACKAGES USED IN CONSTRUCTION OF INTERFACE LOGIC CIRCUITRY OUTPUT LOADING FACTOR /OUTPUT  PROPAGATION DELAY ns TYPICAL  TOTAL POWCOST ER DISSIPA/PKG TION mW TYP/PKG $  QUANTITY USED IN INTERFACE  MOTOROLA NUMBER  FUNCTION  MC834P  HEX INVERTER  DTL  8  30  66  2.00  8  MC845P  CLOCKED FLIP-FLOP  DTL  12  40  60  1.62  1  MC849P  QUAD-2 INPUT NAND  DTL  7  25  66  1.65  17  MC855P  J-K FLIP-FLOP  DTL  11  40  140  2.10  1  MC858P  QUAD-2 INPUT POWER  DTL  27  30  130  2.70  17  MC1803P  8-INPUT NAND  DTL  7  25  16.5  1.55  2  MC1806P  QUAD-2 INPUT AND  DTL  8  35  72  1.90  6  MC1809P  QUAD-2 INPUT OR  DTL  7  30  115  1.90  1  MC4038P  l-OF-8 DECODER  TTL  11  45  240  6.65  1  MC7442P  BCD/DEC DECODER  TTL  11?  45?  105?  6.75  1  MC7475P  QUAD LATCH MEMORY  TTL  10  30  160  4.50  3  FAMILY  o  supply which serves to e l i m i n a t e one l i n e between s e c t i o n s 1 and  2. An u n s h i e l d e d c a b l e , approximately  43 f e e t i n l e n g t h ,  i s used t o t r a n s f e r i n f o r m a t i o n on 13 l i n e s between s e c t i o n 1 and  2; t h i s c a b l e should be kept  as s h o r t as p o s s i b l e .  or c r o s s t a l k problems were experienced  provided  No n o i s e  a l l the l i n e s  were made f a l s e - a c t i v e and power g a t e s , with a s u i t a b l e p u l l - u p r e s i s t o r , were used at the t r a n s m i s s i o n end o f each l i n e . a d d i t i o n great care was taken  In  t o a v o i d ground loops which can  e a s i l y a r i s e d u r i n g the c o n s t r u c t i o n o f complex  electronic  equipment. A f t e r the p r o t o t y p e  i n t e r f a c e had proved  itself  r e l i a b l e over s e v e r a l months o f t e s t i n g , a d o u b l e - s i d e d , p i e c e p r i n t e d c i r c u i t board  was designed  the s e c t i o n 2 l o g i c c i r c u i t r y .  Using  one  (by E. J . B e l l i s ) f o r  t h i s new p r i n t e d c i r c u i t  board, two more complete i n t e r f a c e s were c o n s t r u c t e d and i n s t a l l e d i n the remaining  two 30 cm r a d i u s mass  at the U n i v e r s i t y o f B.C., i s o t o p e geophysics  spectrometers  laboratory. A l l  three i n t e r f a c e s are now o p e r a t i n g and are being used f o r i s o t o p e a n a l y s e s , and i t i s intended computer w i l l sharing b a s i s .  t h a t the one I n t e r d a t a  s e r v i c e a l l three mass spectrometers  on a time  CHAPTER 4  4.1  On-Line F i l t e r i n g  o f Data  The simplest mode o f o p e r a t i o n o f the data  acquisition  system i s the o n - l i n e f i l t e r i n g o f d a t a from the d i g i t a l meter and the d i s p l a y o f the f i l t e r e d  volt-  data on the n u m e r i c a l  readout. P r e v i o u s computer o f f - l i n e  programs designed to pro-  cess mass  s p e c t r a l data have always i n c o r p o r a t e d some  form  of  f i l t e r i n g to reduce h i g h e r frequency n o i s e .  It  digital  t h e r e f o r e seemed reasonable for  to design a d i g i t a l  filter  program  the I n t e r d a t a computer which would d i s p l a y the f i l t e r e d  data p o i n t s at the mass spectrometer  c o n s o l e immediately,  w e l l as s t o r i n g a smoothed v e r s i o n o f the mass spectrum  as  in a  memory b u f f e r , from which i t c o u l d be t r a n s f e r r e d t o magnetic tape v i a the S e l e c t o r Channel. A s u i t a b l e low-pass d i g i t a l by R. D. R u s s e l l and J . Blenkinsop  f i l t e r had been  f o r an IBM 360/67 and t h i s  program was r e w r i t t e n (by J . Blenkinsop) programming language. is  designed  A flow-diagram  i n the I n t e r d a t a  o f the f i l t e r  program  shown i n F i g u r e 16. The  digital  which corresponds amental sampling  v o l t m e t e r produces 5 data p o i n t s / s e c o n d  to a Nyquist frequency  o f 2.5Hz.  The fund-  theorem r e q u i r e s t h a t i n order t o c o m p l e t e l y  r e c o v e r the o r i g i n a l  s i g n a l , the sampling  frequency must be  43.  READ 5 CHARACTERS FROM DIGITAL VOLTMETER \/ CONVERT DECIMAL TO BINARY  7 POINT AVERAGE  SKIP EVERY 2ND POINT  3 POINT AVERAGE  5 POINT AVERAGE >  SKIP 2 OUT OF 3 POINTS  STORE FILTERED POINT  CONVERT BIN . TO DEC.  WRITE 5 CHARACTERS ON DISPLAY  FIGURE 16.  MASS SPECTROMETER FILTER-DISPLAY  PROGRAM  at  l e a s t twice the h i g h e s t o c c u r r i n g frequency  signal.  i n the sampled  P h y s i c a l s i g n a l s , however, do not have a f i n i t e  frequency c o n t e n t .  The p a r t o f the s i g n a l spectrum  above the Nyquist frequency w i l l be r e f l e c t e d and  lying superimposed  ( f o l d e d back) onto lower f r e q u e n c i e s , and the o r i g i n a l can o n l y be r e c o v e r e d a p p r o x i m a t e l y . to  choose the N y q u i s t  sampling  ( f o l d i n g ) frequency  o f the i o n c u r r e n t measuring  (and t h e r e f o r e the  system.  However, f r e -  above 2.5Hz do not c o n t r i b u t e s i g n i f i c a n t l y to the  mass s p e c t r a l r e c o r d s encountered second  The best one can do i s  r a t e ) h i g h enough t o i n c l u d e a l l f r e q u e n c i e s l y i n g i n  the passband quencies  signal  s h o u l d t h e r e f o r e be q u i t e When s e l e c t i n g a f i l t e r  and a sampling  rate of 5 point  adequate. f o r mass s p e c t r a l data i t i s  important t h a t the width o f the t o t a l averaging f u n c t i o n (the data window) i s l e s s than or equal t o the mininum width o f the peak t o p s . is  For the f i l t e r  3.8 seconds  used, the width o f the data window  which n e c e s s i t a t e s d w e l l i n g on a peak top f o r  a p e r i o d o f at l e a s t Digital  3.8  seconds.  filtering  i s accomplished  i n the P r o c e s s o r by  adding t o g e t h e r p o i n t s t o form a moving average  by sevens and  a p p l y i n g every o t h e r averaged p o i n t t o a three p o i n t moving average,  f o l l o w e d by a f i v e p o i n t moving average.  every t h r e e p o i n t s from the f i v e p o i n t average  One out o f  i s stored i n a  memory b u f f e r , c o n v e r t e d from b i n a r y t o decimal n o t a t i o n , and then w r i t t e n on the d i s p l a y . averages  The 7-point, 3 - p o i n t , and 5-point  a l l have tapered e n d p o i n t s , which i s to say t h a t the  end-points have w e i g h t i n g c o e f f i c i e n t s o f one h a l f  ( i n our case)  45.  T h i s has  the e f f e c t o f r e d u c i n g the amplitude  on the f i l t e r  response  o f s i d e lobes  ( F i g u r e 17) .  It should be e v i d e n t from the above d e s c r i p t i o n t h a t t h e r e i s one the f i l t e r ,  f i l t e r e d p o i n t a v a i l a b l e , at the output  f o r every s i x raw  i n p u t data p o i n t s , hence the  d i s p l a y i s updated once every 1.2 The  Nyquist  frequency  seconds.  i s lowered  to 2.5/6  f i l t e r i n g , but s i n c e there i s l i t t l e s i g n a l or n o i s e present  above 0.1Hz, i t i s c l e a r t h a t no  discarded i n this  way.  of  Hz  after  still  i n f o r m a t i o n i s being  a  FREQUENCY-CPS FIGURE 17.  FREQUENCY RESPONSE OF DIGITAL FILTER  CHAPTER 5  SYSTEM PERFORMANCE  5.1  Introduction i  In  o r d e r t o t e s t the accuracy and r e l i a b i l i t y o f  the computer i n t e r f a c e two s t r o n t i u m i s o t o p e a n a l y s e s were performed  u s i n g both an i n t e r l a b o r a t o r y standard and a rock  sample o f unknown  composition.  The mass spectrometer which has been i n t e r f a c e d t o the computer i s p r i n c i p a l l y used age d a t i n g o f rock samples. Rb  8 5  to  N a t u r a l rubidium has two i s o t o p e s ,  which i s s t a b l e , and R b  Sr  with a h a l f - l i f e  8 7  f o r the r u b i d i u m - s t r o n t i u m  8 7  which i s r a d i o a c t i v e and decays  o f approximately  5x10  years.  10  are f o u r s t a b l e i s o t o p e s o f s t r o n t i u m , namely S r * , S r 81  and S r  8 8  Sr  8 7  5 .2  i n c r e a s e s w i t h time.  8 7  i n the sample can be determined,  abundances o f S r age  8 6  ,  Sr  8 7  , and o f t h e s e , i n a c l o s e d chemical system, o n l y the  abundance o f S r of  There  8 7  and R b  o f the sample can be  8 7  I f the i n i t i a l  amount  and the p r e s e n t  i n the sample are measured, the  determined.  P r e p a r a t i o n o f Strontium  Samples  The method d e v i s e d by B. D. Ryan (1971) f o r the chemical s p e a r a t i o n o f s t r o n t i u m from a rock sample i s used. The  rock sample i s crushed t o a f i n e powder and  48.  approximately 0.25 gms i s \tfeighed out i n t o a t e f l o n beaker. The sample i s completely d i s s o l v e d i n H S0i 2  and evaporated t o dryness.  and HF, heated,  t  The r e s i d u e i s d i s s o l v e d by  warming w i t h HC1 and allowed t o c o o l .  The sample i s c e n t r i -  fuged and the s o l u t i o n t r a n s f e r r e d t o the top o f a c a t i o n exchange column, o f l e n g t h 21 cms, c o n t a i n i n g Resin the  (200-400 Mesh).  eluate c o l l e c t e d  Dowex 50W-X8  The column i s e l u t e d w i t h 6NHC1 and i n a measuring c y l i n d e r .  The f i r s t  of  e l u a t e are d i s c a r d e d and the next 40 ml c o l l e c t e d .  of  40 ml i s evaporated d r y and taken up i n 2 ml 2NHC1.  w h i l e , the columns a r e back a s p i r a t e d w i t h 2NHC1. (2  25 ml  The c u t Mean-  The sample  ml) i s added t o the column and e l u t e d w i t h 2 N H C l .  The f i r s t  90 ml o f e l u a t e are d i s c a r d e d and the next 40 ml c o l l e c t e d . T h i s c u t o f 40 ml i s evaporated t o dryness and the r e s i d u e d i s s o l v e d i n 3 drops 2NHC1.  5.3  A n a l y s i s o f Eimer and Amend S r C 0  3  I n t e r l a b o r a t o r y Standard The Eimer and Amend SrC03 was chosen because i t has been analysed a t a l a r g e number o f d i f f e r e n t  laboratories, in-  c l u d i n g The U n i v e r s i t y o f B r i t i s h Columbia,where  i t has been  a n a l y s e d a number o f times p r e v i o u s l y u s i n g the same mass spectrometer. the  Sr  8 7  /Sr  8 6  For the purposes o f i n t e r l a b o r a t o r y comparison r a t i o i s taken as 0.70800.  The S r C 0  3  i s d i s s o l v e d i n 2NHC1 t o produce a s o l u t i o n  c o n t a i n i n g approximately  400ug s t r o n t i u m p e r ml o f 2NHC1.  Two drops o f the s o l u t i o n are d e p o s i t e d  on each o f the outgassed  rhenium s i d e - f i l a m e n t s * and evaporated to dryness by p a s s i n g a c u r r e n t o f about one Amp through each f i l a m e n t while are exposed t o the atmosphere.  they  The two s i d e - f i l a m e n t s and a  rhenium c e n t r e - f i l a m e n t are mounted i n a s t a i n l e s s s t e e l which, i n t u r n , i s p o s i t i o n e d i n s i d e the mass The (< 2 x l 0 "  7  mm Hg). centre-filament  i s heated by p a s s i n g  o f about 4.0 Amps through i t . f i l a m e n t produces e f f i c i e n t  The  spectrometer.  whole system i s evacuated to a low p r e s s u r e  The  being  block  C o l l i s i o n with  a current  the hot c e n t r e -  i o n i z a t i o n o f the sample t h a t i s  g e n t l y evaporated from the r e l a t i v e l y c o o l s i d e - f i l a m e n t s .  p o s i t i v e i o n s produced are a c c e l e r a t e d by a p o t e n t i a l o f  5000 v o l t s and can be focussed variable f i e l d  i n t o a Faraday cup u s i n g a  s t r e n g t h electromagnet.  The charges t h a t  collect  i n the cup, c o n s t i t u t e the i o n c u r r e n t which i s measured, the magnitude o f t h i s c u r r e n t i s d i r e c t l y p r o p o r t i o n a l t o the abundance o f the p a r t i c u l a r Faraday cup. and  a search  rubidium  i s o t o p e i o n beam focussed  The c e n t r e - f i l a m e n t c u r r e n t i s s l o w l y i s made f o r a R b  i s present,  8 5  i t i s burnt  contamination  peak.  i n t o the  increased I f any  o f f the s i d e - f i l a m e n t s at a  f i l a m e n t temperature j u s t below t h a t r e q u i r e d t o produce an appreciable strontium  spectrum.  When the h e i g h t  o f the R b  *The t r i p l e - f i l a m e n t technique o f s o l i d - s o u r c e mass was used f o r a l l the a n a l y s e s .  8 5  spectrometry  50.  peak i s n e g l i g i b l e , which i m p l i e s t h a t the h e i g h t o f the R b peak i s a l s o n e g l i g i b l e  ( s i n c e the r a t i o R b / R b 8 5  8 7  = 2.593 i s  8 7  c o n s t a n t ) , the c e n t r e - f i l a m e n t c u r r e n t i s i n c r e a s e d t o a value such t h a t a S r with  the output  f o r rubidium  contamination 8 5  the s t r o n t i u m The  peak h e i g h t o f about 1 V o l t i s o b t a i n e d  attenuator  ature and i f a R b before  8 8  s e t on shunt 3.  A check i s made  at t h i s new c e n t r e - f i l a m e n t  peak i s s t i l l  d e t e c t a b l e i t i s burnt  away  spectrum i s scanned.  strontium  86, 87 and 88 peaks are scanned i n  sequence about 12 times by v a r y i n g the magnet f i e l d u s i n g a peak-hopping t e c h n i q u e . are read  temper-  The peak h e i g h t s  intensity  and b a s e l i n e s  from the f i l t e r d i s p l a y and are w r i t t e n by hand on  the c h a r t r e c o r d e r which p r o v i d e s  a v i s u a l r e c o r d o f the spec-  trum. In o r d e r t o c a l c u l a t e the S r scan  i t i s necessary  8 7  /Sr  8 6  r a t i o f o r each  t o c o r r e c t the measured r a t i o f o r the  growth o r decay o f the peak h e i g h t s , then t h i s r a t i o i s c o r r e c t e d f o r mass d i s c r i m i n a t i o n a t the i o n s o u r c e . peak h e i g h t s  grow o r decay almost l i n e a r l y and hence a c o r r e c t i o n  is easily applied. due  Discrepancies  i n the i s o t o p e abundances  t o mass d i s c r i m i n a t i o n ( f r a c t i o n a t i o n ) can be simply  t e d f o r i n the case o f s t r o n t i u m constant scan  (=0.1194).  8 7  The S r  8 6  /Sr  s i n c e the r a t i o S r 8 8  8 7  /Sr  correc8 6  is  r a t i o i s c a l c u l a t e d f o r each  and the d i s c r i m i n a t i o n p e r u n i t mass determined. An  Sr  F o r t u n a t e l y the  /Sr  8 6  average value  f o r the c o r r e c t e d  (normalised)  r a t i o over a l l the scans i s c a l c u l a t e d , t o g e t h e r  with  a value f o r the standard d e v i a t i o n of the mean. The  r e s u l t , given i n Table IV, i n d i c a t e s about a  t w o f o l d i n c r e a s e i n p r e c i s i o n over p r e v i o u s v a l u e s o b t a i n e d by J . B l e n k i n s o p , u s i n g the same mass spectrometer, the computer  5.4  without  interface.  A n a l y s i s of S t r o n t i u m i n a Rock Sample As a f u r t h e r t e s t o f the performance o f the computer  i n t e r f a c e two  analyses were performed  sample . s e l e c t e d was  a light  on a rock sample.  grey a r g i l l i t e  The  ( s l i g h t l y metamor-  phosed c l a y s t o n e ) from the C r e s t o n f o r m a t i o n o u t c r o p p i n g i n S.E.  B r i t i s h Columbia.  T h i s f o r m a t i o n i s p a r t o f the  Purcell  S e r i e s which i s s t r a t i g r a p h i c a l l y e q u i v a l e n t to the B e l t S e r i e s which outcrops i n western and Barnes  Montana and n o r t h e r n Idaho.  (1966) r e f e r t o these two  Supergroup.  The  s e r i e s as the  Smith  Belt-Purcell  Supergroup, which crops out over an area o f  more than 50,000 square m i l e s , c o n s i s t s l a r g e l y o f metamorphosed sediments which have not undergone i n t e n s e d e f o r m a t i o n . nesses  of g r e a t e r than 40,000 f e e t have been a t t a i n e d .  sediments c o n t a i n no u s e f u l d a t a b l e f o s s i l s  (1400  - 900 m.y.  Obradovich  [million  and Peterman (1968) have dated rocks o f techniques.  minations y i e l d ages r a n g i n g from about 900 m.y. m.y.  Precambrian  years]).  the B e l t S e r i e s u s i n g Rb-Sr and K-Ar  1300  The  and t h e r e f o r e p r o -  vide e x c e l l e n t m a t e r i a l f o r isotope dating studies of rocks  Thick-  Their detert o around  Rb-Sr i s o t o p e measurements performed by Ryan Blenkinsop  (1971) on the H e l l r o a r i n g Creek Stock i n the  P u r c e l l Mountains i n d i c a t e an approximate age T h i s s t o c k , which i n t r u d e s the lowest the P u r c e l l S e r i e s recognized  of 1260  m.y.  known formation  Columbia.  sample o f a r g i l l i t e  was  c o l l e c t e d by Dr. W.  Barnes of the Geology Department, U n i v e r s i t y of B.C., made a v a i l a b l e to the w r i t e r by Mr.  B. D.  Ryan.  C. Croucher, have shown t h a t t h i s sample c o n t a i n s ( p a r t s per m i l l i o n ) rubidium  was  chemical  c a r r i e d out twice  B) from the one t i o n was  248  ± 2% ppm  80  by ± 2%  to p r o v i d e  two  strontium  specimen of a r g i l l i t e .  samples  This duplicate  5.2 (A  B should  and  separa-  a check on the r e p r o d u c i b i l i t y  s i n c e , i d e a l l y , samples A and  ppm  strontium.  spearation described i n Section  used to p r o v i d e  the chemistry  and  C.  and  X-ray f l u o r e s c e n c e measurements, performed  The  of  (the A l d r i d g e Formation) , i s the o l d e s t  in British The  was  and  of  yield  i d e n t i c a l i s o t o p e abundance r a t i o s . Mass s p e c t r o m e t r i c  analyses  o f samples A and  B were  performed i n a s i m i l a r manner to t h a t d e s c r i b e d i n S e c t i o n for  the Eimer and Amend s t a n d a r d .  of s t r o n t i u m  i n the a r g i l l i t e  much lower  Consequently i t i s  ensure t h a t a l l the sample i s d e p o s i t e d  which n o r m a l l y  maintain  important  on the s i d e - f i l a m e n t s ,  e n t a i l s p i p e t t i n g three or more drops of s o l u t i o n  onto each s i d e - f i l a m e n t . still  concentration  samples n e c e s s i t a t e s much g r e a t e r  care i n the f i l a m e n t p r e p a r a t i o n . to  The  5.3  In order  to perform t h i s t a s k ,  and  a l l the sample w i t h i n the middle o n e - t h i r d upper-  s u r f a c e o f each s i d e - f i l a m e n t r i b b o n , the f o l l o w i n g technique has been found s a t i s f a c t o r y .  P l a c e one drop o f s o l u t i o n i n  the c e n t r e o f each s i d e - f i l a m e n t , s l o w l y evaporate the drop to dryness by p a s s i n g a c u r r e n t o f about one Amp  through  each f i l a m e n t , c o o l c o m p l e t e l y , add another drop t o the middle o f each r i b b o n , evaporate t o d r y n e s s , and so on u n t i l all  the sample s o l u t i o n i s shared e q u a l l y between the s i d e -  filament.  The c u r r e n t through each f i l a m e n t i s then i n c r e a s e d  u n t i l the f i l a m e n t s glow w i t h a d u l l r e d c o l o r and are then left  t o "cook" f o r about one minute.  h e l p s produce  This l a t t e r  procedure  a more s t a b l e i o n beam.  Table V g i v e s the r e s u l t s o f the two mass e t e r runs f o r the samples  spectrom-  A and B and the c o n c e n t r a t i o n s o f  the f o u r i s o t o p e s o f s t r o n t i u m i n the a r g i l l i t e  sample.  These  c o n c e n t r a t i o n s were c a l c u l a t e d u s i n g the X-ray f l u o r e s c e n c e data and the r a t i o S r  8 7  /Sr  8 6  d e r i v e d from the mass spectrometer  runs. The percentage d e v i a t i o n from the mean o f the r a t i o SR  8 7  /Sr  8 6  at a 95% c o n f i d e n c e l e v e l i s about 0.05% which  good o r b e t t e r than p r e v i o u s a n a l y s e s performed on rock u s i n g the same chemical s e p a r a t i o n procedure and mass e t e r without the d i g i t a l  f i l t e r i n g of data.  i s as samples  spectrom-  OH  TABLE IV  .  RESULTS OF ANALYSES OF EIMER S AMEND INTERLABORATORY  STANDARD SrCQ  RATIO ( S r  LABORATORY  8 7  /Sr  3  8 6  )  COMMENTS  n  0.7080±0.0002*  ON-LINE FILTER, HAND CALCULATED (THIS THESIS)  UBC (RYAN § BLENKINSOP, 1971)  0.7082±0.0004  HAND CALCULATED  USGS (STACEY ET AL, 1971)  0.7080±0.0002  DIGITALLY RECORDED $ COMPUTED  USGS (STACEY ET AL, 1971)  0.7079±0.0006  HAND CALCULATED  MIT (SPOONER $ FAIRBAIRN, 1970)  0.7082±0.0008  HAND CALCULATED  YALE (DASCH, 1969)  0.7075±0.0012  HAND CALCULATED  U o f T (PURCY § YORK, 1968)  0.7080±0.0012  HAND CALCULATED  ACCEPTED VALUE  0.70800  UBC  (RUSSELL ET AL, 1971)  RESULTS OF ANALYSES OF GREY ARGILLITE  TABLE V  RATIO  SAMPLE  8 7  /Sr  A  0.7419±0.0003*  B  0.7420±0.0005  CONSTANT RATIOS: Sr VSr - 0.0568 8  8 6  ISOTOPE CONCENTRATIONS (TOTAL)  80  8 6  )  n  0.7419±0.0004  MEAN OF A 5 B  RK  (Sr  1  (TOTAL-' 248  86  S r  / S r  88  =  0.1194  ( p a r t s per m i l l i o n ) ±2% Qr r S ' 1  b  1.3  &  9 T  8  6  r  23.9  b  r  <!r  8 7  17.9  b  T  ^ r  8  8  204.8  * - ALL UNCERTAINTIES QUOTED ARE TWO STANDARD DEVIATIONS (95%  CONFIDENCE LEVEL)  CHAPTER 6  6.1  Conclusions The  to  analyses d e s c r i b e d i n Chapter  5 were not expected  show any a p p r e c i a b l e i n c r e a s e i n p r e c i s i o n over p r e v i o u s  a n a l y s e s , performed  on the same mass spectrometer, without the  computer i n t e r f a c e , but o n l y to t e s t the d e s i g n and o p e r a t i n g reliability  o f the system.  With t h i s end i n mind one can o n l y  be very s a t i s f i e d w i t h the r e s u l t s so f a r o b t a i n e d .  The f u l l  p o t e n t i a l o f t h i s o n - l i n e data a c q u i s i t i o n system w i l l  o n l y be  r e a l i z e d when the p r o c e s s o r i s programmed t o determine  peak  h e i g h t s and b a s e l i n e s , c o n t r o l scan r a t e s and apply the v a r i o u s analytical  corrections. J.  Blenkinsop has completed  a p r o t o t y p e program t o  p r o v i d e o n - l i n e p r o c e s s i n g o f data from the mass and h i s i n i t i a l r e s u l t s , from s e v e r a l t r i a l r u n s ,  spectrometer indicate  about a t h r e e f o l d i n c r e a s e i n p r e c i s i o n over p r e v i o u s  off-line  analyses. No f u r t h e r improvements i n the hardware are envisaged i n the immediate f u t u r e , although p o s s i b l e areas o f i n v e s t i g a t i o n may l i e w i t h the computer c o n t r o l o f source c o n d i t i o n s and the d i r e c t  r e a d i n g o f the magnetic f i e l d  i n t e n s i t y f o r each  peak. There remains great scope f o r improvements i n the software and i t i s i n t h i s channelled.  field  t h a t much e f f o r t  i s being  BIBLIOGRAPHY  A l b e e , A.L., B u r n e t t , D.S., Chodos, A.A., E u g s t e r , O.J., Hun^eke,' J.C. , P a p a n a s t a s s i o u , D.A., Podosek, F.A., Russ, G.P., Sanz, H.G., T e r a , F., and Wasserburg, G.J. (1970). Ages, i r r a d i a t i o n h i s t o r y , and chemical composition o f l u n a r rocks from the Sea o f Tranquility. S c i e n c e 167, 463. Catanzaro, E . J . (1967). T r i p l e f i l a m e n t method f o r s o l i d sample l e a d i s o t o p e a n a l y s i s . J . Geophys. Res., 72, 1325. Compston, W., and Oversby, V.M. u s i n g a double s p i k e .  (1969). Lead i s o t o p i c a n a l y s i s J . Geophys. Res., 74_, 4338.  Dasch, E . J . (1969). Sr i s o t o p e s i n weathering p r o f i l e s , deepsea sediments , and sedimentary rocks . Geochim.. Cosmochim., 3_3, 1521. Data Technology Corp. I n s t r u c t i o n Manual 344 Meter (part No. 18915-10).  4 Digit/Systems  I n t e r d a t a , Inc. (1969). Reference Manual ( p u b l i c a t i o n No. 29004R02). Systems I n t e r f a c e Manual ( p u b l i c a t i o n No. 29-003R02). M o t o r o l a Semiconductor Products Inc. (1968). C i r c u i t Data Book.  The I n t e g r a t e d  Obradovich, J.D., and Peterman, Z.E. (1968). Geochronology o f the B e l t S e r i e s , Montana. Can. J . E a r t h S c i . , 5_, #3, p a r t 2, 737. P a p a n a s t a s s i o u , D.A., and Wasserburg, G.J. (1969). I n i t i a l Sr i s o t o p i c abundances and the r e s o l u t i o n o f s m a l l time d i f f e r e n c e s i n the f o r m a t i o n o f p l a n e t a r y o b j e c t s . E a r t h § P l a n e t . S c i . L e t t e r s , 5_, 361. Purdy, J.W., and York, D. (1968). Rb-Sr whole rock and K-Ar m i n e r a l ages o f rocks from the S u p e r i o r P r o v i n c e near K i r k l a n d Lake, n o r t h e a s t e r n O n t a r i o , Canada. Can. J . E a r t h S c i . , 5_, 699. Ryan, B.D., and B l e n k i n s o p J . (1971). Geology and geochronology o f the H e l l r o a r i n g Creek s t o c k , B.C. Can. J . E a r t h S c i . , 8, 85.  57.  R u s s e l l , R.D., B l e n k i n s o p , J . , Meldrum, R.D., and M i t c h e l l , D.L. (1971). O n - l i n e computer a s s i s t e d mass spectrometry f o r g e o l o g i c a l r e s e a r c h . J o u r n a l o f the P h y s i c s o f the E a r t h ( i n p r e s s ) . Smith, A.G., and Barnes, W.C. (1966). C o r r e l a t i o n s o f and f a c i e s changes i n the carbonaceous , c a l c a r e o u s , and d o l o m i t i c formations o f the Pre-cambrian B e l t - P u r c e l l Supergroup. B u l l . G e o l . Soc. Amer.,77, 1399. Spooner, CM., and F a i r b a i r n , H.W. (1970). Sr /Sr initial r a t i o s i n pyroxene g r a n u l i t e t e r r a n e s . J . Geophys. Res., 75, No. 32 , 6706. 8 7  8 6  Stacey, J.S., R u s s e l l , R.D., and K o l l a r , F. (1965). Servo-amp l i f i e r s f o r i o n c u r r e n t measurement i n mass spectrome t r y . J . S c i . I n s t . , 42, 390. Stacey, J.S., W i l s o n , E.E., Peterman, Z.E., and T e r r a z a s , R. (1971). D i g i t a l r e c o r d i n g o f mass s p e c t r a i n g e o l o g i c s t u d i e s , I . Can. J . E a r t h S c i . , 8_, 371. Wasserburg, G.J., P a p a n a s t a s s i o u , D.A., Nenow, E.V., and Bauman, C A . (1969). A programmable magnetic f i e l d mass spectrometer w i t h o n - l i n e data p r o c e s s i n g . Rev. S c i . I n s t . , 40 , 288. Weichert, D.H. (1965). D i g i t a l a n a l y s i s o f mass s p e c t r a (Ph.D. T h e s i s , U n i v e r s i t y o f B r i t i s h Columbia). Weichert, D.H., R u s s e l l , R.D., and Blenkinsop J . (1967). method f o r d i g i t a l r e c o r d i n g f o r mass s p e c t r a . P h y s i c s , 45, 2609.  A Can. J .  APPENDIX I.  ION CURRENT AMPLIFIER $ OUTPUT ATTENUATOR CIRCUIT. ( Designed by R.D.Russell, June 1969. )  STEPPING MOTOR  -28v L O  nrrYTYn.  APPENDIX I I .  SCAN DRIVE CIRCUIT (designed by R.D.Russel1 , June  1966)  60.  APPENDIX I I I . SUMMARY OF INTERDATA PROGRAMMING INSTRUCTIONS*  • CODE 01 02 03 04 05 06 07 08 OA OB OC OD OE OF 28 29 2A 2B 2C 2D 40 41 42 43 44 45 46 47 48 4A 4B 4C 4D 4E 4F 60  TYPE RR RR RR RR RR RR RR RR RR RR RR RR RR RR RR RR ,RR RR RR RR RX RX RX RX RX RX RX RX RX RX RX RX RX RX RX RX  MNEMONIC BALR BTCR BFCR NHR CLHR OHR XHR LHR AHR SHR MHR DHR ACHR SCHR LER CER AER SER MER DER STH BAL BTC BFC NH CLH OH XH LH AH SH MH DH ' ACH SCH STE  INSTRUCTION Branch and Link Branch on True Condition Branch on False Condition AND Halfword Compare Halfword OR Halfword Exclusive OR Halfword Load Halfword Add Halfword Subtract Halfword Multiply Halfword Divide Halfword Add with Carry Halfword Subtract with Carry Halfword Floating-Point Load Floating-Point Compare Floating-Point Add Floating-Point Subtract Floating-Point Multiply Floating-Point Divide Store Halfword Branch and Link Branch on True Condition Branch on False Condition AND Halfword Compare Logical Halfword OR Halfword Exclusive OR Halfword Load Halfword Add Halfword Subtract Halfword Multiply Halfword Divide Halfword Add with Carry Halfword Subtract with Carry Halfword Floating-Point Store  OP CODE 68 69 6A 6B 6C 6D 90 92 93 96 97 9A 9B 9D 9E 9F CO Cl C2 C4 C5 C6 C7 C8 CA CB CC CD CE CF DO Dl D2 D3 D5 D6 D7 DA DB DD DE DF *  -  TYPE RX RX RX RX RX RX RR RR RR RR RR RR RR RR RR RR RS RS RX RS RS RS RS RS RS RS RS RS RS RS RX RX RX RX RX RX RX RX RX RX RX RX  MNEMONIC LE CE AE SE ME DE UNCH STBR LBR WBR RBR WDR RDR SSR OCR AIR BXH . BXLE LPSW NHI CLHI OHI XHI LHI AHI SHI SRHL SLHL SRHA SLHA STM LM STB ' LB AL WB RB WD RD SS OC Al  INSTRUCTION Floating-Point Load Floating-Point Compare Floating-Point Add F l o a t i n g - P o i n t Subtract Floating-Point Multiply Floating-Point Divide Unchain Store B y t e Load Byte Write Block Read B l o c k Write Data Read Data Sense Status Output C o m m a n d Acknowledge Interrupt B r a n c h on Index H i g h B r a n c h on Index L o w o r E q u a l L o a d P r o g r a m Status W o r d A N D H a l f w o r d Immediate C o m p a r e L o g i c a l H a l f w o r d Immediate O R H a l f w o r d Immediate E x c l u s i v e O R Halfword Immediate L o a d H a l f w o r d Immediate A d d H a l f w o r d Immediate Subtract H a l f w o r d Immediate Shift R i g h t L o g i c a l Shift Left L o g i c a l Shift R i g h t A r i t h m e t i c Shift Left A r i t h m e t i c Store M u l t i p l e Load Multiple Store B y t e Load Byte Autoload Write Block Read Block Write Data Read Data Sense Status Output C o m m a n d Acknowledge Interrupt  Reproduced, b y p e r m i s s i o n , from I n t e r d a t a Reference Manual #29-004R02.  62. APPENDIX IV MASS SPECTROMETER INTERFACE PROGRAMMING GUIDE ADDRESSES HEX D - M.S.2 HEX E - M.S.I HEX F - M.S.3  STATUS AND COMMAND BYTE DATA  BIT NUMBER  0  2  1  3  4  6  5  STATUS BYTE  DU  .-REAl3  COMMAND BYTE  DU  -  ( )-WRI rE r  The d e v i c e  unavailable b i t  power supply READ  -  si •QUENi :ING  i s s e t when the M.S. 5v  i s off.  T h i s command s e t s the output command memory so t h a t data can be read  WRITE  7  -  from the M.S.  T h i s command s e t s the OC memory so t h a t data can be w r i t t e n on the d i s p l a y . The scan r a t e i s a l s o controlled  SEQUENCING  i n the w r i t e mode.  B i t s 5,6 and 7 are used f o r sequencing the data i n both the read  and w r i t e modes.  READ SEQUENCING BIT NUMBER  4  -  5  COMMAND BYTE  6  7  1  •Read DVM overrange  1  1 1  1  1  1  1  1  1  1  1  1  1  1  1  1  Data  •Read DVM decades i n sequence  1  1  -Read shunt  -Read scan d i r e c t i o n  1  -Read f u n c t i o n s e l e c t  i s read u s i n g the OC i n s t r u c t i o n  read d a t a  code switch  f o l l o w e d by the  (RD) i n s t r u c t i o n .  WRITE SEQUENCING  COMMAND BYTE  BIT NUMBER  6  S  4  number  7  1  •Write on d i s p l a y decades i n sequence  1 1  1  1 1  Data  1  1  1  1  1  -Write decimal p o i n t -Set scan r a t e  1  -Not  used  i s w r i t t e n u s i n g the OC i n s t r u c t i o n  w r i t e data  (WD) i n s t r u c t i o n .  f o l l o w e d by the  64.  DVM  DECADE NUMBERING  OVERRANGE  DISPLAY  1  (Front view).  2  3  DECADE NUMBERING  0  1  2  4  (Front view)  3  4  

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