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Your number's up again

Ian Wilson looks at how calculator manufacturers are keeping pace with new demands. What's new in calculators? This may seem a rather pointless question - how can there be much new in something so familiar as the calculator? But technological change applies here as much as to other machines.

The changing requirements of teachers responding to new demands, whether from the national curriculum or from the examination boards, is also a factor very much in the minds of the three big companies - Casio, Texas Instruments and Sharp - who dominate the market.

As Nicola Eagle of Texas Instruments says, "We don't just build calculators in a vacuum. For the last 20 years we have worked closely with teachers and educationists to deliver the machines they need to match the maths concepts taught."

This process led Texas Instruments to develop the TI-92. This combines the power of a palmtop computer with the versatility of a graphics calculator. It can also handle interactive geometry and and will undoubtedly prove to be a most desirable acquisition for A-level and higher education students.

From Casio comes news of three additions to its extensive range. At the primary level is the D-100LC, a large, robust machine with a hinged screen which runs on both solar power and batteries. It is basically a four-function machine with some of the features, such as a separate key for entering "hundreds" found on office desktop models. Its most interesting feature is the review facility for checking calculations. For example, if you are adding a column of figures, when you have finished you can press the review button, and then enter the figures again. If you have made any errors, it beeps at you and by pressing an arrow key, you can see what you entered the first time. The keys are large, and the 10-digit display is clear, showing the operations as well as figures. The only drawback is likely to be the switches which can be used to control decimal places, but perhaps these could lead to some interesting discussions about decimal notation.

Due out next month are two secondary graphics calculators, the FX-7400G, described as an intermediate graphing calculator, and the CFX-9850G, a colour graphics machine. The FX-7400G has larger keys than many graphic calculators, and a reasonably clear screen. However, the display seemed unacceptably jagged, even on linear functions and when used to draw a simple polynomial such as x3, produced a series of steps rather than even an approximation to a curve.

The CFX-9850G uses three different colours to draw graphs, and has a much better display than the other machine, with acceptable curves. Both machines have a user-friendly menu system for zooming, tracing, finding intersections and so on, accessed from a row of buttons below the screen.

Sharp has announced four new machines, due out in the next few months. These all come with versions of DAL (Direct Algebraic Logic), which enable calculations to be entered as they are written. The EL-530L is described by Sharp as a completely new concept, a basic scientific calculator aimed at upper primarylower secondary pupils as an introduction to scientific calculators. It is slightly wider than usual, which allows for fairly large keys, well spaced and clearly labelled, and it comes with an ingenious sliding case top. The range of functions is limited to three trigonometric ratios and to operations on fractions. All the operations and figures are displayed until the equals button is pressed, and two arrow buttons allow you to scroll back and forth through the sequence altering any of the inputs. If you make an error, such as entering an operation twice in succession, an error sign appears and by pressing one of the arrow buttons, the source of the error is revealed. My only reservation concerns the robustness of the keys, but this calculator, at a very reasonable price, is well worth considering by both primary and secondary schools.

The other three calculators (EL- 531LH, EL-520L and EL-546L) all have a similar integral lid and the arrow buttons which allow correction of input or of errors. It is also possible with these to return to the original equation even after the equals button has been pressed. The EL-520L is a twin power machine and will be suitable for all secondary pupils up to A-level. The top of the range EL-546L has every function needed at A-level and many beyond, including the ability to perform complex number calculations and six different kinds of regression. What more could you ask for?

Casio D-100LC Pounds 19.99; FX-7400G and CFX-9850G approx Pounds 90. Casio, Unit 6, 1000 North Circular Road, London NW2 7JD. Tel: 0181 450 9131 Texas Instruments TI-92 Pounds 199. Texas Instruments, Kempton Point, 68 Staines Road West, Sunbury on Thames, TW16 7AX. Tel: 01784 212000 Sharp EL-530L Pounds 6.99; EL-531LH Pounds 8.99; EL-520L Pounds 13.99; EL-546L Pounds 16.99. Sharp Electronics, Sharp House, Thorp Road, Manchester M40 5BE. Tel: 0161 205 2333

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