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Introduction - C.Basic, a part of C:Basic Project

If you want to run your Casio Basic program much faster, C.Basic free your frustration!

Get started with your genuine Casio Basic program. Also enjoy extended commands that genuine Casio Basic cannot do.

  • Currently C.Basic (interpreter) runs in fx-9860G and fx-9860GII, but will support PRIZM fx-CG10 and fx-CG20. [17th Jan, 2017]
  • C.Basic will evolve to Casio Basic compiler "C:Basic", it will run much faster than C.Basic (in factor of 10 we think). [17th Jan, 2017]


All the instruction of C.Basic are in "README_J.txt" and "Manual_L.txt" included in C.Basic disribution package, but all in Japanese. This is why this site is created in English. Please be paitient until translation work is completed. [17th Jan, 2017]

C.Basic is a part of C:Basic Project. The Project C:Basic will provide Add-In Casio Basic Interpreter and Compiler. At this moment C.Basic (single dot) an Basic interpreter is released.

C.Basic is supplied as an Add-In program for fx-9860G and fx-9860GII. fx-CG10/20 is also targetting platform.

In the future C:Basic (double dots, colon) will include compiler version.

What is C.Basic?

C.Basic is designed for Fast, compatible with genuine Casio Basic and also bringing in some of good features of fx-5800P.

C.Basic uses program file (*.g1m) stored in storage memory. Genuine Casio Basic uses also g1m file stored in main memory. A program source using only compatible commands can run in both of C.Basic and genuine Casio Basic.

Add-In Casio Basic Interpreter (& Complier)
copyright(c)2015 by sentaro21
e-mail to auther: sentaro21(at)pm.matrix.jp
e-mail to administrator & author of this site: Krtyski(at)gmail.com


  • C.Basic includes almost compatible commands with genuine Casio Basic.
  • Prgoam runs faster in C.Basic than genuine Casio Basic (in factor of 10 or more).
  • Usability of File List and Editor is almost similar or easier to use than Casio Basic.
  • C.Basic stores program files in storage memory and supports sub-folder structure.
  • Some of Casio Basic compatible commands are extended for more features
  • C.Basic has also newly implemented commands for more powerful and flexible programming.


  • C.Basic does not cover all of genuine Casio Basic commands.
  • Calculation error and accuracy of C.Basic are deferent from genuine Casio Basic, since C.Basic is developed in C language with Casio SDK and it uses double-precision binary operation.
  • C.Basic stores PICT file in storage memory, so handling PICT file takes a bit more time than genuine Casio Basic. (in Ver 0.87 or later version the process is faster, since heap area in main memory can be used for PICT file).
  • There still probably remain some bugs, it's unfortunate but sure (^^; so please give us a bug report.

Almost compatible but not 100% with genuine Casio Basic

Compatibility with genuine Casio Basic is our target, but not 100%;

  • An input line by command "?" and "?→" are only in single line. A string of characters more than 21 columns is displayed still in the horizontal single line by scrolling, not in multiple lines.
  • When ":" (Multi-statement Command) comes right after graphing sketch command, graphic screen is not re-drawn.
  • Program running time is displayed after the program quit. This function can be set on or off in setup page.
  • A Comment Text Delimiter ' is available for comment-out before Carriage Return or ◢ (output), but ":" (Multi-statement Command) can be included the commented out string. 

C.Basic also takes in user-friendly feature of fx-5800P; 

  • C.Basic does support a script "?A" supported by fx-5800P. This is not supported by fx-9860G / fx-9860GII (script "?→A" only is supported).
  • Function of string output command " " is fully compatible with fx-5800P in details but not exactly compatible with fx-9860G/fx-986GII. See Topics in details. 


We do not believe that C.Basic could damage your calculator. But there still be possibility that main memory could be unexpectedly damaged or destroyed and "memory all reset" might be required. It’s strongly recommended that you should make backup of data in main and storage memory of your calculator. Please be aware that you should use C.Basic at your sole risk.

Disclaimer of Warranty

Use of C.Basic and C:Basic (hereinafter SOFTWARE) is at user’s sole risk. All materials, information, products, software, programs and service provided “as is”, with no warranties or guarantees whatsoever. Creators of SOFTWARE and support team who provide support documents, support web site, information and sample programs (hereinafter DEVELOPMENT TEAM) expressly disclaim to the fullest extent permitted by law, all express, implied, statutory, and other warranties, guarantees, or representations, including, without limitation, the warranties of merchantability, fitness for a particular purpose, and non-infringement of proprietary and intellectual property rights. Without limitation, DEVELOPMENT TEAM makes no warranty or guarantee that development of SOFTWARE will be uninterrupted, timely, secure, or error-free. 


Installation of C.Basic

  1. Download C.Basic package at "Get the new version" page ⇒ see important note
  2. Transfer CBasic.g1a file (Add-In file) to storage memory of your fx-9860GII (use PC link software FA-124A).
  3. To start up C.Basic, press [MENU] key and select C.Basic icon.
  4. To check version of C.Basic, press [SHIFT] [MENU] [F6](Ver.), then version is shown.
  5. When the version is same as what you want to install, the installation has been done correctly.
  6. To return back to File List, press [EXIT] and [EXIT] again.
  7. CBasic.g1a is rather large file, so Optimization of memory is recommended to do. Press [MENU], select MEMORY icon, press [EXE] and press [F5] (Optimization).

Start Up C.Basic

To start up C.Basic, press [MENU], select C.Basic icon then press [EXE].

Assuming a program source file (g1m file) has been developed by genuine Casio Basic, there are 2 ways to copy the sourece file to File List in C.Basic;

1. Use memory Manager, one of add-in program initially installed.

  • To run Memory Manager, press [MENU], select Memory manager icon then press [EXE].
  • Press [F1] to show file list in Main Memory.
  • Move cursor to then press [EXE]. Now program file list of original Casio Basic program files (g1m files) is shown.
  • Move cursor to select program file which you want to copy.
  • Press [F1] (SEL) and [F2](COPY).
  • Now Cursor is on "ROOT", then press [EXE], then screen is switched to File Name.
  • Enter an appropriate file name (for example just "A"), then press [EXE].
  • Press [MENU] to go back to MAIN MANU
  • Start C.Basic.
  • In File List page select "A" which you entered, press [F6] and [F2] (REN).
  • [Rename File Name?] is poped up and the original file name is shown there even you entered appropriate file name "A", then press [EXE].
  • Now the file name is corrected.

2. Use PC link software (FA-124)

FA-124 is a PC link software which is included in the package of fx-9860G and fx-9860GII. For detailed operation please refer its manual.

When you have downloaded source file (g1m file), please use the PC lin software to copy the g1m file to File List in C.Basic.




To investigate and implement internal specification, "SuperH-based fx calculators (version 20)" gave useful information.

For file handling in C.Basic, "Wsc & Fvm V1.2 - Casio Fx-9860 Series On-calc C Compiler" gave useful information.

For Japanese Kana font data and its output routine, "何かの足跡" gave useful information.

For detailed feature and function of genuine Casio Basic, following site is referenced;
"e-Gadget - Programming Calculator (プログラム関数電卓)" by Krtyski
(contents are almost in Japanese).

Many thanks to my friends.

by sentaro21



C.Basic is a free software in accordance with GPL Ver 2.


inserted by FC2 system