Casio CFX 9850 G

...that....

The Casio name in itself is enough to make many people take notice. Casio have an excellent reputation for making good calculators, and I think it's entirely deserved. Their experience with school-level calcs means that their products tend to be robust and well-built, which is the case with the CFX-9850G. Everything is made of hard-wearing plastic, including the keys. At first, their slightly loose feel can be alarming, but ...
...forward, to enter (and store) Casio programs on the PC and transfer them to the calc when ready, isn't a possibility. There is, I believe, a third-party communication lead available from one of the Casio enthusiast websites, but this only works for Calc<-->PC transfers; Calc<-->Calc communications don't seem to work at all, which is a shame as there would otherwise be a multiplayer capability!

So, do I recommend this calculator? ... more

Graphic calculators have come a long way in recent years. I bought one of Casio's earliest efforts in the sector, the fx-7000GA (which I still have), about eight years ago, and thought it was the bee's knees. Putting it side by side with my current workhorse, the CFX-9850G, however, points up just how far things have advanced in that time. The older machine had a whopping 422 bytes(!) of RAM, for example - this one has about 60 times that....

The Casio name in itself is enough to make many people take notice. Casio have an excellent reputation for making good calculators, and I think it's entirely deserved. Their experience with school-level calcs means that their products tend to be robust and well-built, which is the case with the CFX-9850G. Everything is made of hard-wearing plastic, including the keys. At first, their slightly loose feel can be alarming, but in fact this play is a good idea - after all, the reed which bends before the wind survives the storm; the oak which stands rigid does not. There's also a tough plastic slide-on case, which protects the calc very well.

The first thing you notice when you extract the calculator from its box is the enormously thick manual (which it shares with the slightly more upmarket CFX-9950G model). Aha, you think to yourself, this must be one of those multi-language instruction books. But no, all 400+ A5 pages are in English. This amount of space means several things, all of them good. Firstly, there is a worked example for pretty much every one of the calc's 900 or so functions - with screenshots for most of them. Secondly, information that is often left out or relegated to a separate "tech sheet", such as how to replace the batteries (4 AA for general use and one CR2032 for backup) is covered properly, with clear instructions. And thirdly, the print is actually large enough to read! (One exception to this, irritatingly, is the command "at a glance" table inside the back cover, which is enough to make anyone's eyes ache.)

Turn on the calculator, and the first thing you see is (unsurprisingly) the main menu - a slightly intimidating array of 14 possible modes. You'll probably only use a handful in everyday use, though, which makes things easier. Controls and commands, other than the most common, are entered via a rather complicated menu system using the six function keys at the top. This does take some learning, as it's very easy to forget which command is accessed from which menu, especially given the fact that some of the menus change according to what you are currently trying to do (and, of course, because of that tiny print in the manual!). Proficiency does come, in time, but you do need to work at it (I think) a little harder than you should have to.

So, once you've got your calculator going, what can you do with it? To be honest, it's more a question of what you *can't* do with it, and the answer to that is "not a lot". To give you a (very brief) idea, this calculator will deal with quadratic differentials; integration; complex numbers; matrices; cubic equations; five types of regression; polar coordinates; implicit functions... I'd better stop here, or I'll fill up hundreds of words just writing this list!

Quite a few of these functions, of course, make use of the CFX-9850G's graphic capabilities - and here again we see major improvements over the first-generation graphic calcs. Instead of a smallish, rather hard to see monochrome screen, we now have a three-colour, zoomable 128x64 pixel display (21x8 characters in text mode), which makes it a great deal easier to distinguish between two graphs (when determining points of intersection, for example). This colour capability also makes games rather more fun... but that's for a little later on.

A particularly useful part of the calc's graphical capabilities is the ability to animate your graphs (the "dynamic display"). By that I mean that you can define a formula, such as Y=A(X+B)^2+C, enter the starting coefficients, then choose one coefficient (eg A) to be changed dynamically. For example, you might make A increase from 1 to 5 in steps of 1. The calc will "think" for a few seconds, and then you will be presented with the "animation", wherein the relevant graphs will be drawn one after another, allowing you to see the way in which altering A (or whatever) has changed the graph's shape.

There are lots more features available in the graphic department: the ability to compare two separate graphs side-by- side; drawing a line or curve of best fit when doing regression analysis; creating a graph-to-table display, which allows you to summarise graph analysis results in a textual format; histograms; probability graphs; determining integrals and shading the area under the graph... again, it just goes on and on.

Next, let's consider the calculator's programming capabilities. The CFX-9850G is considerably more powerful than many early computers, having 28K of program memory (it says 32K on the box, but 4K is reserved for the system), and a programming language that is very reminiscent of BASIC. For example, you can incorporate For-Next or While loops, If-Then-Else constructs, Gotos (cries of "back, foul fiend!" from programmers...) subroutines and even Getkey, which can be used to detect keypresses. This means that some very powerful programs can be written - the short examples section at the back of the manual includes a figure rotation program, which works a lot faster than my old ZX81 did! And yes, it also means that you can write games - the Getkey function's presence enabling even (very simple) action games to work. Until recently, I had a rather good Connect 4 program in memory, which worked very well, but was rather tedious to enter...

...which brings me to one of the CFX-9850G's few drawbacks. According to the documentation, you can buy communications leads which will allow your calc to "talk" to either a PC (running appropriate software) or to each other. The trouble is that these leads appear to be unobtainable, at least in the UK. This means that the obvious way forward, to enter (and store) Casio programs on the PC and transfer them to the calc when ready, isn't a possibility. There is, I believe, a third-party communication lead available from one of the Casio enthusiast websites, but this only works for Calc<-->PC transfers; Calc<-->Calc communications don't seem to work at all, which is a shame as there would otherwise be a multiplayer capability!

So, do I recommend this calculator? Most certainly. If you shop around, you might well be able to pick it up for around fifty pounds - and when you consider the power you're getting for that money, it's very good value indeed. 

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