Brand: CASIO
Model: CFX-9850GB PLUS
Type: Graphical programmable scientific calculator
Picture: CASIO fx-9850GB PLUS
Batteries: AAA x 4 + CR 2032 x 1 (memory backup)
Lifetime: Introduced: ca. 2000
Terminated: unknown
Notes: This is the CASIO model used quite a lot in schools in The Netherlands in 2001/2002. I bought this one brand new myself, it has been a very long time since I bought any calculator brand new. This time it was different however, as it turned out the shop where I bought it accepted AirMiles as money, so in my view I bought it for free :-)

This calculator is very much like the other high-end CASIO calculator in my collection, the CASIO fx-9700GE. However, there must have been models in between.

There are more models in the 9850 series. I've seen references to:
  • CASIO CFX-9850G
  • CASIO CFX-9850GB
  • CASIO CFV-9850GB PLUS (this one)
But there are so many calculators it's hard to keep track with them.

Icon Menu The CASIO CFX-9850GB PLUS has a colour display (see the calculator's Icon Menu to the right). I'm not sure if the 9850 is the first CASIO with a colour display or not. The colour display has some advantages and some disadvantages. It's really great with multiple graphs, but the readability of the screen is not as good as you'd get with regular LCD's. When used with plotting functions, each function can be set to one of the three available colours, blue, orange or green. The Icon Menu is really nice. Not a chance of getting lost on this calculator.

Spacer Icon Menu The screen colours can be adjusted on a per-colour basis, as can be seen on the screen dump to the right here. I reckon the LCD dot's colours are changed by adjusting the driving voltage or maybe the frequency. I don't think there's more than one display layer. Spacer
Lewin Edwards wrote me, concerning this calculator's display:

Hello Ernst,

Great web site. I found it through researching CASIO color calculator LCDs.

Just FYI- For many years (since the first CASIO color data bank, which I bought ~1994) I had believed these LCDs have 2 layers. Lending credence to this is an apparent "parallax difference" visible at the border between two color areas, e.g. orange and blue...

However - It transpires that these LCDs are in fact regular single-layer TN devices. The different colors are obtained by PWMing the drive signal. It's an interesting idea, and apparently nobody besides CASIO has used this technique (maybe they patented it). The magic is not in the LCD itself, but in the driver IC - and these types of drivers appear to be CASIO ASICs, not available off-the-shelf.

Okay, the calculator's functions.

When compared to the earlier CASIO fx-9700GE I have to say this calculator's keyboard layout is much better. Functionally I can't see any fundamental differences. Take a look at that calculator's page for some of this calculator's features.
New however are the financial functions, no need to buy a separate special financial calculator anymore.

The case is quite ugly IMHO, but the protective cover is much better and can not really damage the display anymore. Thanks, CASIO!


This calculator can be hooked up to a PC using a PC-link cable and PC-link software (available from CASIO, but there are also third-party versions around on the net). The schematics for the link cable can be found on the net as well. I've cached two versions (version 1 and version 2) that are technically practically identical.