Topics in..
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Chemical Instrumentation
I 'a!5D
feature
Edited by GALEN W. W I N G , Seton Hall University, So. Orange, N. J. 07079
These arlicles are intended to serve Me readers o f ~ ~JOURNAL r s by calling attention to new developments i n the theory, design, or availability of chemical laboratory instrumentation, or by presenting useful insights and ezplanations of topics that are of practical importance lo those who use, m leach the use of, modern instrumentation and inslmmental lechniques. The editor invites correspondence from prospective contributors.
LXXXV. Calculators for the Chemist (Concluded) Stewart Karp, Department o f Chemistry, C . W . Post College o f Long
Island University, Greenvale, New York 11548
Desk T o p Calculators Desk top calculators are now well into their second and later generations. I t is impossible to summarize briefly what is available; however, a number of product lines will be described in some detail to give an idea of what can be obtained. Table I1 is an attempt to present a t a glance examples of the typical basic calculators available. Hewlett-Packard has a broad line of desk calculators starting with preprogrammed computing calculators with printers designed for specific purposes such as the model 9805 statistics calculstor, or for general work such as the HP-46 similar in its capabilities to the HP-45 pocket calculator. Four programmable scientific calculators (9810, 9820, 9821 and 9830) are marketed by Hewlett-Paekard. The 9810 has 51 data memory registers available to the user in the basic instrument; the 9820 and 9821 have 167 registers; while the 9830 has about three times that many. All are easily expandable. The 9830 with a mass memory subsystem can be expanded to over a million words of accessible memory. Programming is performed from the keyboard and can be permanently recorded on magnetic cards on the 9810 and 9820. The 9821 and 9830 use cassette tape for recording programs while the 9830 has an optional disc memory. The 9810 uses Reverse Polish notation, which was discussed above, while the 9820 and 9821 use an algebraic language mixed with English notes
giving it a conversational feeling. The 9830 is programmed in BASIC providing the advantage of having available many programs which have been written far computers. The 9810, 9820 and 9821 have interchangeable plug-in function blocks to define sets of keys. These blocks may be preprogrammed or user defined. Examples of the preprogrammed blocks are a mathematics block for trigonometric and logarithmic functions, a peripheral black for controlling, plotters, typewriters, etc. The user definable blocks can he specified by the operator and stored far future use. The function blocks do not eat into the main calculator memory and are, of course, in addition to the programming capability. A varied line of peripherals are available including card readers, tape punch and readers, typewriters, X-Y plotter and interfacing to some digital voltmeters, counters and other laboratory instruments. The cost for a calculator system is illustrated by the following. The 9821 basic calculator is just under $5000. To increase the 167 registers by another 423 costs under an additional 31000, while increasing by 1447 registers costs under $3500. Plug in function blocks are $500 each. An X-Y plotter Nns about $2800, while a card reader is about $2700. It is apparent that flexibility of' purchasing is available and systems can be built up gradually. Wsng Laboratories, one of the earliest companies in the electronic desk calculator business, now has s complete line of modem calculators. Their basic line consists of four series. The 400 series is the
lowest in cost. The model 450 scientific calculator's basic price is under $1000, and for about $300 more the basic 64 program steps available can be expanded to 320 steps. The 16 basic storage registers can be expanded by utilizing the program steps as data storage, 8 program steps to one data register. Many functions such as exponential~, logarithms, etc., are preprogrammed and keys are available for the operator to design as dedicated function keys. A rather large library of programs is available fmm Wang including roots of a quadratic, error function, least squares fit, statistical programs and many others. Programs can be stored on and read from cards which need an optional peripheral, running about $400. The Wang series 600 programmable ealculators start with a base price of $2600 for a calculator which has 16 keyboard registers and can handle 312 program steps (program steps and data registers can be interchanged). The calculator can be expanded stepwise. For example, $300 can extend the memory by 512 program steps. Extended memory ol over 4000 pmgram steps can be added. Other options include an automatic printer and tape cassette storage of programs. Among the peripheral equipment available are plotters, paper tape reader and interfacing for laboratory equipment. This latter interface, ineidentally, is only $300, and allows direct input from digital devices such as voltmeters and counters. The series 700 base price is $5000, and it has 120 storage registers or (Continued on pogeA375)
Volume 52, Number 8. August
1975 / A373
Table 2.
Scientific Programmable Dark C a l c u l a t o r s 0 Pricee
5
C o m ~ a n yand Model canon.
1°C.
CBnola SX-100
Funcrion KW*
storage
Parmsnenf storage
OPnanlsnd ~erinherals
Printer
d
Included
5 1 regirterr
many
available
167 regirterr
many
available
many
avallsble
many
Included
nane
none
Pmprosrammed math keys + 5 definable
5 0 data memo,ier 500 program
2 lntsrcnangeable
rtepr ~swlett-~acuard 9810
functlon block% prepcogrammed and definable 3 interchangeable fY"Cti0" OlOCkI, Dreprogrammsd and definable Same as 9820
9820
9821
167 registars 74 data registers 512 program
Monroe 186011880
rteor 100 oreprogrammed owrations PTeprOgrammed math tunctianr
12 data regirterr 416 Program steps 64 step program 12 data regirterr 144 Program steps 10 (Iata regirterr 128 program
Tape casette Magnetic card ornional t a w casette
...
aVaIIabIB
many
available
Tape cartridge Optional caras
many
standard
some
none
OPtional tape carrette
many
available
Ta w CaPIefte
many
available
stem 74 date regirterr 512 Dragram steps 16 data
NO. 31
wang 400 rerier
Itorage
600 rerier
Definable t o 32
700 rerier
Definable t o 6 4
6 4 Ploplam (interchang* able, I 6 data + 312 program (interchangeable) 120 data + 960 program (i"telc"an9eable1
n A representative sampling of oa.k model.. noes not i n c ~ v d acalculators using a computer language. tnsrefore some top line models are not tabulated. b AII use algebraic logic, except where noted. e h p ~ r o x i m a f eand rublect to cnange. d sx.31b w m have interface caosbllltisr. e User Rwerre Polis" Notation.
-,,-.u.........
~
....
A374 / Journal of Chemical Education
Chemical Instrumentation
Figure 3. Wang'sSystern 2200.
Figure 2 . Wangs Seres 600 calculator with
avariety of peipherals.
960 pmgram steps. Larger capacities are available. Some of what is optional on the series fi00 is standard an the 700, i.e.. magnetic tape cassette for permanent storage of programs. Again a wide range of peripherals are available (Fig. 2) Wang's top of the line is their advanced Programmable System 2200 (Fig. 3). System it is, for it has over 30 peripheral devices available. T h e user can custom purchase a system for his needs and add to it as needs develop. The language is BASIC and the display is a large cathode ray tube (16 lines of 64 characters/linei. The basic unit (central processing unit) has almost 4000 (4K) steps (bytes) of available storage and is priced a t only $3.500. A magnetic tape cassette reader/recorder and enpandability raise the price to $5500. T h e internal memory can be expanded in 4K incre(Continued on paceA.7761
Volume 52, Number 8. August 1975 / A375
Chemical Instrumentation ments to 32K and a disk memory peripheral can expand this to the millions. Additional peripherals available include output typewriter and printers, plotters and punched tape handling. Tektronix markets two programmable calculators, models 21 and 31. The model 21 has 30 built-in math functions with 8 keys which can be defined by the user. Program memory is held in 8, 16-step blocks for a total of 128 steps and there are 10 data registers. Conditional and unconditional branching is available. Programs are permanently stored on magnetic cards. The price is under $1900, but an installed printer adds $450. Options include memory expansion up to 512 steps and an X-Y plotter. The Tek 31 model is appreciably more powerful. It has 74 data registers and can handle 512 program steps (expandable up to about 1000 registers and about 8200 steps). It has additional programming ability such as editing power, sub-routine nesting and a programmable flag. Programs and data can be stored on a magnetic tape cartridge. The price far the model 31 is $3550, which includes a huilt-in alphanumeric printer. For under $6000 the Tektronix 31/53 system combines the model 31 with the model 153 instrumentation interface which holds two plug in measurement instruments such as counters and multimeters. The 31/10 graphic csleulator system combines the model 31 calculator with the 4010 graphic terminal which displays on a
A376 / Journal of Chemical Education
19 x 14 cm display area cathode ray tube. Cost for this combination is $8500. A rather new entry is the Canola SX-100 programmable desk calculator by Canon, Inc. In addition to the expected function keys there are 5 user definahle keys. The ample 50 data memories and 500 program steps can he split and thereby doubled. Programs can be stared and read fmm magnetic cards. Editing is easily performed and conditional and unconditional branching is possible. The calculator features a built-in printer with alphanumeric ability which is a full 14 cm. wide. The price (including printer) is under $2700. The soon to be available SX-310 will have the ability to interface with peripherals; it will cost under $2900. Monroe's model 1860 and 1880 desk top calculators for scientific use have 74 data registers (expandable to 522) and 512 program steps (expandable to 3072). Magnetic cards are used for permanent storage and the units have built in printers. These units can be interfaced with a variety of peripherals such as X-Y plotter, punched card reader and counter. The Alpha 325 model with a built in printer, mid-priced a t under $1800, has 12 data storage regist e n and holds 416 program steps. A magnetic tape cassette drive adds about $400, hut allows permanent storage of programs and data. Monroe has a hand held programmable calculator, the Beta 326 (5 X 2 X 9 in.), which has an accessory tape cassette drive (Fig. 4). It is not exactly pocket size but is surely carryable in a brief case. More than 100 operations are preprogrammed on the keyboard and it can han-
Figure 4. Monroe's Model 326, hand held programmable calculator with interfaced magnetic t a w cassette drive. dle 160 step programs utilizing 12 storage registen. It has editing capabilities and the optional cassette tape storage ability makes this portable combination very powerful. Other interfacings are possible, as with s teletype or CRT display. Price is $895, which includes a tape cassette. For $495 Monroe's 324 hand-held calculator can store 2 different 80-step programs a t the same time, has 20 of the usual math functions and can do register arithmetic in 10 storage registers. Sharp Electronics Corp, has a full line of desk top (as well as pocket) calculators. Notable is PC-1002 (Fig. 5). which for $645 has the expected function keys and can handle 64 step programs. Their CS-360 (Continued on page A.378)
Chemical Instrumentation line features more powerful programmable models with magnetic card permanent storage of programs and printers. T h e CS-364P-I1 has 12 data storage registers. 144 main pmgram steps and another 144 in subroutines. It is interesting to compare the above with a 1970 publication (3) which reviewed available desk top calculators. T h e technology in this field is advancing very rapidlv indeed.
Applications I t is safe to say that. irrespective of field or type of employment, there are more chemists today who have something to do with computers than there are those who must utilize the gas laws. I t is no surprise, therefore. that introductions to computers are now offered to undergraduates, a t times even to general chemistry students I f , . 5 ' One approach to acquainting students with the use of computers in chemistry is through the use of desk top pmgrammable calculators. There are two obvious advantages of such an approach. The first one is the low initial cost, especially important when a digital computer is not readily availahle. Secondly, the pmgrammsble calculator allows the student to do calculations and write programs
A378 / Journal of ChemicaiEducation
--
Figure 5 Sharp Elecfrormcs Model PC-1002 calculator.
Corpoimon's
without first learning a computer language. For some this may he the preferred approach to introducing computers to students, for it allows them to concentrate on the logic and concepts unclouded by "new rules" which must be adhered to. Successful experience with programming calculatom should provide incentive to many for undertaking the study of computer language and use. Many reports concerning the use of calculators in the educational field have appeared. A few of these uses. other than straightforward calculations. will be mentioned.
A programmable calculator system (HP-9100A with extended memory and a plotter) was used to draw stereo pair pictures of crystal structures 16). T h e appmach is shown to be suitable for high school levels on u p to college physical chemistry students. The simulation of a number of experiments with programmable calculatom have been described. Some fairly simple experiments; e.g.. titrations, kinetics and equilibria, are suggested to supplement. not replace, actual laboratory work (7). Experiments which for one reason or another cannot readily be performed or far which only limited data can be obtained can be made available by means of calculator simulation (8,9). A number of calculations previously handled by digital computers have been performed by desk calculators. For example, the calculation, using a programmable calculator, of enthalpy and entmpy of evaporation from pressure-temperature data and the Clausius-Clapeymn equation has been compared with a similar FORTRAN program (20). Another example is the use of a programmable calculator in place of a FORTRAN program and digital computer for the calculation af solute dipale moments fmm dielectric constant and density measurements (11). A 1239-step pmgram for use on the Wang 720-B calculator was described for the calculation and plotting of Morse wave functions 112). An investment in a programmable calculator has been shown to be useful in alleviating some of the more tedious aspects of the teacher's duties; e.g., grading multi-
ple choice (A.C.S.) examinations (13). It should be no problem to relegate the calculation of final averages to a desk top calculator. It is expected that calculators will find much use interfaced with laboratory equipment. As an aid to such usage a signal averaging program has been presented for use with analog voltage signals where the signal-to-noise ratio is poor (14).
Interfacing Interfacing of computers and minicomouters to laboratow eauioment has been given much attention 115). The use of programmable calculators interfaced with laboratory equipment has, in many cases, advantages over computer and minicomputer usage. One advantage is lower cost. However, there is overlap in the prices of the larger calculator systems and minicomputers. Proper selection depends on the requirements. Another advantage is the ease of programming the calculators. This is of narticular i m ~ o r ift the users are
