memory. After completion of the experiment, the data can be written to a disk in the form of a text file that is available for manipulation by slave programs to calculate reaction rates, aK's. etr. ~ o i d e t a i l of s the software, hardware, and techniclues used for the construction, write to Richard Cornelius, ~ e p a r t m e n t of Chemistry, Wichita State University, Wichita KS 67208. Acknowledgment This work was supported by National Science Foundation Grant No. CHE-8024043.
A Program for Determining the Symmetry Types of the Normal Modes of Vibration Figure 8. Autotitrator and pH-stat showing card, and power supply.
syringe drive. stepper motor, driver
Figure 9 Screen display show~ng litration curve, pH. v3iuma. and number of point on curve.
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increased hy simply using a larger syringe and changing one or two lines in the software. If the pH-stat is to he used t o determine reaction kinetics directly, a clock card in the microcomputer greatly facilitates monitoring the reaction. A photograph of the apparatus is given in Figure 8. Because the most difficult part af construction was securing the hardware and comnonent uarts. comnlete details of the uarts - - ~ ~ ~ h pH-meter k BCD o&ut used and the sources will be is transmitted via a standard ribbon cable to a 2 X 8 bit Dar-
Michei Schneider, Jean-Victor Weber, and Pierre Faller, Laboratoire de Chimie Organique Universite de Metz Ile du Saulcy, 57045 Metz, France In the scope of a course on molecular spectroscopy it is necessarv to introduce arouu theorv ( 5 ) .esoeciallv for determining the number of the findamektal bands in the infrared and Raman suectra. This au~licationof rrouu theorv is of great interest for the student;, but unfort&ately some steps are rather tedious for groups of high symmetry (6), and too long a calculation discourages the students. We report here that we have developed a comuuter Drorram IRRA for determining the symmetry types of the normal modes of vihration, the IR andlor Raman active fundamentals, and the number of bands in the IR and Raman spectra of amolecule. The students only enter the uoint group and the characters of the reducible representation (using internal coordinates or Cartesian displacement vectors). IRRA can also perform the reduction of any reducible representation into its irreducible components. Actually, twenty point groups are available: Czv - CE,; D,; D3; D2h - D G ~D2d ; - D G ~Td; ; Oh. We have also developed a short program (2K) GROPO for determining the point group of a molecule. GROPO is an interactive Basic program that asks the student for the symmetry elements of any molecule. IRRA has been written in Basic and implemented on a C.B.M. 4032 computer. Execution requires 17 K. This program should be readily transferred to other computers. A urorram listine and a C.B.M. 4032 comuatible cassette taDe &e&ailahle frbm the a'uthors. For costsand postage, send i n international money order made out to M. Schneider ($5.00 for the program listing; $10.00 for the cassette tape).
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Carrihean Drive, Sunnyvale, CA 94086). The same interface is used to send commands to the sterner motor; one interface card handles both input of data andoutput of control signals. Onlv one outuut uort is required for the signal to the motor driv"e card which Lntrols the stepper m o t o r r ~ o t hthe stepper motor we used (Type 20-2215D200-31.5)and the driver card (Type 29A-43) were supplied by the Sigma Instrument Company (Braintree, MA 02184).The stepper motor used had a step angle of 1.8' which provided a high degree of control over reactant addition. The micrometer drive was obtained from Stoeltine Comoanv (1305 S. Kostner Ave.. Chicago. IL 60623). Both the reabing of p ~ a n the d steppingof the &tor are accomplished by BASIC subroutines. The relatively slow execution of BASIC is not a problem here; the response of the elass electrode is the factor that limits the speed of e x ~ e r i -
PETNET: Many PETKBMs-One Disk William M. Butler and William Levak University of Michigan Ann Arbor, MI 48109 Kalie Gehring and John W. Moore Eastern Michigan University Ypsiianti. MI 48197 I t is possible to connect several Commodore PETICBM microcomputers to a single Commodore disk drive using standard CBM to IEEE cables. Such a network ereatlv reduces the cost per machine of program loading fAm adisk drive. Bv means of a ~ ~ r o n r i asoftware. te the network can be ment at the ~niversityof Michigan has been using n&e CBMS connected to a Commodore 8050 disk drive since Januarv 1982, with very few failures. The chemistry department a t Eastern Michigan University has been using a similar system since September 1982. We describe here the hardware and software requirements for such a system. Volume 60 Number 2
February 1983
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