Figure 2. Facsimile of the STPPLT output on the Tektronix screen for kinetic by SCN-. date collected from the reduction of ~e(bipy)j+ lightly commented. The programs are user-oriented and carry out their functions automatically; however, for testing purposes and because of the possible requirement of minor modifications due to graphics display limitations, these proerams are easilv. senarated into their functional comnonents. . The necessary statements are included as remarks. Four additional programs, LOAD, MONBK, CHMON, and S T P are included. These are written in MACRO, require 4K-16 bits and are downloaded from the 11/45 automaticalls. Some are fully commented. All the programs and the interface should he transportable to other systems. We will make availahle detailed schematics, operating instructions, listings, sample output, and/or a listing on your tape (7 tracks, ASCII, odd parity, 800 BPI, unblocked) or floppy disk (for Tektronix 4921, ASCII, manual-tape mode). Send a blank tape or disk and a check for $10 made payable to Stanislaus State College Foundation, in care of Dr. Jim Byrd, Department of Chemistry, California State College, Stanislaus, Turlock, California 95380.
A Microcomputer-Controlled Gamma Scintillation Spectrometer Joseph W. Long
to analog-analog to digital converter provides communication between the comnuter and the external analoe world (Cromemco, Inc., 280 Bernardo Avenue, Mountain View, California 94040). Figure 8 shows how the computer and scintillation equipment are interfaced. The interface hardware hetween the computer and scintillation equipment consists of operational amplifiers that serve to match the voltage levels between the various parts of the soectrometer and the computer. After manual calibration of the pulse height analyzer and adjustment of the energy window width, the spectrometer may he operated completely under control of the microcomputer. The controllable parameters include upper and lower energy scan limits, scan speed, and direction. A scan may he interrupted, then continued, restarted from the heginning or aborted by single commands from the terminal. The chart recorder is controlled by the computer, which provides both the pen signal and chart-advance pulses. As a soectrum is run. it mas be outout to either the chart recorder; the terminal (as a high resolukion graphical display) or both. Once run, spectra may be saved on disk for reuse later. Latest versions of the ~ o r i z o nComputer allow storage of over 250 complete spectra on a single diskette (see Fig. 4). The software has been prepared in such a way that a student familiar with manual operation of the spectrometer requires perhaps ten minutes of instruction to operate it under computer control. This has been done by displaying on the terminal a "prompt line" that indicates the currently available operator commands a t all points within the program. Student response to this equipment has been enthusiastic and the system has proven useful in several ways: Students are intnldured to laboratory camputen, their interfacing and operation. 2) An inexpensive instrument of limited usefulness and rather poor reproducibility has been converted into a powerful, versatile, in a word-"intelligent"-spectrometer, comparable to commercial equipment costing many thousands of dollars. (This is not an in1)
Figure 3.
Spectrameter-mmputerinterlacing: black diagram. (IH = interface
hardware.)
Broome Community College Binghamton. NY 13902 This paper will describe a microcomputer-controlled scannina aamma scintillation soectrometer that has been construEteh in the Chemistry ~ e p a r t m e n at t Broome Community College. The spectrometer is in use by Chemical Technology and Medical Laboratory Technology students for whom it provides an example of microcomputer applications in chemical instrumentation. The spectrometer consists of "Nucleus" (The Nucleus, P. 0. Box R, Oak Ridge, Tennessee 37830) scintillation equipment interfaced to a Northstar Horizon I1 microcomputer. (Northstar Computers, 2547 Ninth Street, Berkeley, California 94710) The Nucleus equipment includes a NaI detector, nuke-heieht analvzer. and GM rate meter that toeether iuncrim d. a usahle, if primitiw. ganlma rpertronwter. T l w rwnputer inclucl(,sdual minillop))). disk d r i w and n videoterminal ([.ear S~egler,lnc., -14 North Rrookhur;t Street, Anaheim. C'aliiornia Wb0.1, to which hm heen added low-wsr. high rralurit~n.graphics hardware that emulstrs the Tektrmix 1010 gr;~phirstcwninal (Digital Knginrering. Inc.. 1775 'I'rihte Ihad, 5acrament0, California YShl51..An h-bit (liyital
550
Journal of Chemical Education
Figure 4. '%s spectrum replotted horn disk. Steps result hom use at an %bit analog to digital converter.
These programs are designed in order to allow a person who may nu1 he computer-oriented to use them easily and efficiently. Programs run from a terminal are totally interactive many mrdifications of the equipment hemme a matter nt'changing and prvvide cumplete error recovery. Almost all operating the program, rather than the hardware. One such contemplated svstem runstreams are eenerated and executed bv the DIOchange is the addition of search-and-match routines to allow grams themselves. In addition, programs and commands decumparism of an unknown spectrum against the floppy-disk lisirned tu be used onlv a t specific times during the semester hrary spectra. (e.g., laboratory setup or final averages) are protected from 4) The comnuter is not limited to use with iust the scintillation access a t all other times. Manv of the security and programming techniques used are unique but cannot be described adequately within the scope of this paper. The functiuns of this svstem can he divided into five distinct duty areas. These are presented separately. Laboratory Setup These programs set up the hookkeeping are in use wlthm thm department on the Northstar cornp&erI necessary for the system operating during the semester. Throueh a comouter terminal. the instructor enters which The control nroeram. GAMSNSOD. written in Northstar lahoratory sections are open, the number of students expected, Basic has 650 statements and 400 comments. GAMSNSOD the orufessors in charge, and the experiment due dates. The reauires a dual disk Horizon with 56 K X 8 of memorv. toget'her with hardware mentioned above. Program G A M S N ~ ~ system then generates coded numhers for the liquid unknowns. prints student sirn-in sheets and unknown bottle is similar hut does not require graphics hardware. Documenlabels, and punches computer cards for use during the setativn includes listing (specify which program) and additiunal mester. After the first lahoratorv meeting, students provide infurmation on interface hardware for $5.00 oostaee and computer cards on which are punched their names, team and handling. Make check payahle to Joseph W. L&, fiepartunknown numbers, and individual security codes. The ment of Chemical Eneineerine Technuloev. Broome Comgradebooks set up from these cards by the system will store munity College, Box 1017, ~ i n i h a m p t o nN, Y 13902. Copies all ofthe grades for the semester. of programs (single density) available on your Northstar disk Student Trml Runs. The data for final grading is due one free of chargs. Include SASE fur return of disk. week alter the experiment is completed. However, prior to this Acknowledgment the student may submit his data in the form of "trial runs" through a terminal or via cards. This is the only area of the I would like to thank Mrs. Esther R. Shafer for outstanding svstem actuallv accessed bv the student. The svstem checks secretarial help. This project was supported by a SUNY Grant this suhmission for punching, format, and calculation errors for Improvement of Undergraduate Instruction. and mints aoorooriate error messaees that show the deductions that wt;;ld i e assessed if the d& were submitted in this A Comprehensive Computer Program System for condition fur final grading. However, the student is not informed at this stage of the accuracy of the final result. an Undergraduate Physical Chemistry Students mav use trial runs as often as necessary to elimiLaboratory1 nate all errors. A record of trial runs is kept autom&cally by K. D. Snell.2 C. V. Braun, Jr., and A. G. Keenan the system so that the instructor is able to observe which University of Miami students are using trial runs and any discrepancies that arise Coral Gables, FL 33124 may he resolved. Experiment Final Grading. The student snhmits data in One semester of our undergraduate physical chemistry . . a format that includes a personal security code that verifies lahoratory program contains experiments involving the that the submission is made hy the correct student. A results identification of an unknown organic liquid through the grade of up to 100 points is assigned, based on the percent measurement of its physical properties, such as density, vapor difference between the student's result and the accented value pressure, molecular weight, heat of vaporization, boiling point, from the literature for the particular physical property. The refractive index, viscosity, and surface tension. A literature grading scale varies with each experiment according tu the survey of chemical abstracts and standard reference works is inherent experimental errm in the measurement. Deductions carried out by the student to identify the liquid. Due to the for calculation and punching errors and for lateness are anlarge enrollment in this lahoratory and in order to ensure tumatically assessed, hut the instructor can override them if consistent operation of all lahoratory sections, it was desirahle necessary. The final grade is stored in the gradehook. to have a computer he responsible for experiment grading and Output from thegrading programs is important to both the lahoratorv hookkeeoine. . ... such as the setuD of the lahoratory instructor and students. The students receive a gradesheet records a t the beginning of the semester, the handling of for each suhmitted experiment and, if one or more experimultiole and late submissions for grading, and grade storape. ments are overdue, a latesheet, which lists these experiments This ;eleases the instructor frommundane paper shuffling and encourages their prompt suhmission. The instructor retasks and increases efficiencv during the laboratory session ceives a listing of deductions and final grades for the suhhy allowing more time to he devoted to student interaction. mitted experiments, a record of trial runs and a current The computer .propram system descrihed here accomplishes "gradebook." these purposes. The word system is used because a series of This gradehook includes, for each experiment, the present 31 stand-alone and interlocking programs is involved. The final grade and data on repeats, resuhmissions, late deducpra>gr;tmittrr ilu~t(*ras? t o uprratt,. Hou,t.wr. the $\>ten> hations, instructor overrides, disolaced grades, instructor deI n thv tact that rludent gr,+(l~.aan. t w c l i ~ n (t , c u r ~ t \requirrd . involved. Most of the securitv is internal. automatic and invisible, requiring the user to provide only a few security codes on an accompanying message page. The gradehook is designed in order to access the system. The programs are written in to give the instructor a complete uverview of the current status LINIVAC ASCII FORTRAN, an ANSI standard FORTRAN, and past history of the sectiun. with some suhroutines written in UNIVAC 1100 ASSEMBLY language. The system is run on a UNIVAC 1100/81 computer. ' Presented in part at the ACS Florida Section Meeting-in-Miniature. ASCII FORTRAN is a powerful Ianruage, incorporatinp the Tampa. FL. May 1980. Author to whom correspondence should be addressed. advanced features of P L / ~into FORTRAN. ~~
Volume 58
Number 7
July 1981
551
