Mark Wickens

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Grammar Overview

This section describes the syntax and structure of the Casio JIS Standard BASIC language.

Program Structure

Sentences (Lines)

Each BASIC sentence (line) has the following structure:

[line number] Command Operand [: Command Operand [: ...]]

• If a line number is present at the beginning, the line is stored as part of a program.
• If there is no line number, the line is executed immediately when EXE is pressed (direct mode).
• Multiple statements can be placed on a single line, separated by colons (:).

Line Numbers

• Range: 1 to 65,535
• Line numbers determine the order of execution.
• The RENUM command can renumber lines at regular intervals.

Line Length

• Maximum 255 characters per line.
• BASIC keywords are stored as single-byte tokens internally, so a line that appears long on screen may use less memory than expected.

Variables

Variables are classified into four types based on data type and structure:

	Single Variable	Array Variable
Numeric	Numeric variable	Array numeric variable
Character (String)	Character variable	Array character variable

Variable Naming Rules

1. Must not contain reserved words. (Conversely, because keywords are tokenized, delimiters like spaces around reserved words can be omitted.)
2. The first character must be an uppercase letter (A-Z), lowercase letter (a-z), or Katakana character (codes &HA6-&HDF).
3. After the first character, uppercase letters, lowercase letters, Katakana, and digits (0-9) are allowed.
4. Variable names can be up to 255 characters long.
5. Uppercase and lowercase letters are different characters. For example, A and a are separate variables.
6. Numeric variables, character variables, array numeric variables, and array character variables with the same name can all exist simultaneously. For example, DIM A(10) and A$ can coexist alongside A.
7. The standard string variables A$ to Z$ are limited to 30 characters maximum length.

Variable Scope

• Variables and arrays are global — they are shared across all 10 program areas (P0-P9).
• Variables are reserved (allocated) on first use.
• Use VARLIST to display the names and types of all currently allocated variables.

Care must be taken because global variables can cause bugs when multiple programs use the same variable names.

Arrays

1. An array must first be declared with a DIM statement before use.
2. Array subscripts are integers greater than or equal to 0. If a fractional value is given, it is truncated.
3. The maximum number of dimensions is 255 (limited by the 255-character line length of a DIM statement).
4. The maximum value of each subscript is limited only by available memory.
5. An array variable cannot be used unless it has been declared with DIM.

Data Types

Numeric Values

• Display: 10-digit mantissa with 2-digit exponent
• Internal precision: 13-digit mantissa (BCD) with 2-digit exponent
• Range: 0 and ±1 × 10⁻⁹⁹ to ±9.999999999 × 10⁹⁹
• Numeric values are displayed as integers, fractions, or exponential notation, with the format selected automatically based on the value.
• Positive numbers are preceded by a space; negative numbers by a minus sign.
• A space is added after displayed numeric values.

String Values

• Maximum length: 255 characters (for extended string variables)
• Standard string variables (A$ through Z$): maximum 30 characters
• Only the + operator is valid for string operations (concatenation).
• The result of concatenation must be within 255 characters.

Operators

Arithmetic Operators

Operator	Operation	Example
+	Addition	A + B
-	Subtraction (or negation)	A - B
*	Multiplication	A * B
/	Division	A / B
^	Exponentiation	A ^ B
¥	Integer division	A ¥ B
MOD	Modulo (remainder)	A MOD B

Comparison Operators

Comparison operators return -1 if true and 0 if false.

Operator	Meaning
=	Equal to
<> or ><	Not equal to
<	Less than
>	Greater than
<= or =<	Less than or equal to
>= or =>	Greater than or equal to

String comparison: Strings are compared character by character using their character codes, from left to right. When one string is a prefix of another, the shorter string is considered smaller.

Expression	Result
PRINT "ABC" < "ABD"	-1 (true)
PRINT "DEF" < "ABC"	0 (false)
PRINT "ABC" > "ABCD"	0 (false — shorter string is smaller)

Logical Operators

Operator	Operation	Example
NOT	Bitwise NOT	NOT A
AND	Bitwise AND	A AND B
OR	Bitwise OR	A OR B
XOR	Bitwise XOR	A XOR B

See LOGICAL for details.

Operator Precedence (Arithmetic Priority)

Operations are evaluated in the following order, from highest to lowest priority:

Priority	Operation
1 (highest)	Parentheses ( )
2	Built-in functions (SIN, COS, etc.)
3	Exponentiation ^
4	Negation - (unary minus)
5	Multiplication *, Division /, Integer division ¥
6	Modulo MOD
7	Addition +, Subtraction -
8	Comparison operators (=, <>, <, >, <=, >=)
9	NOT
10	AND
11	OR, XOR
12 (lowest)	String concatenation + (for strings)

Rounding Behavior

The Casio pocket computers perform internal calculations with 13-digit BCD precision but display only 10 digits. Rounding behavior after the four basic arithmetic operations can be controlled:

• MODE10 — Enable rounding after arithmetic operations (default)
• MODE11 — Disable rounding after arithmetic operations

When rounding is enabled (MODE10) on the FX-870P/VX-4:

• If digits 11-13 are 049 or less: round down (truncate)
• If digits 11-13 are between 050 and 949: no rounding
• If digits 11-13 are 950 or more: round up

Note: Constant substitution (direct assignment like A = 1.123456789049) is not rounded even when rounding after arithmetic operations is enabled. Rounding only applies to the results of arithmetic operations (e.g., A = A * 1).

Note: The FX-890P/Z-1 uses stricter rounding thresholds (007 and 990 respectively).

Variable Memory Usage

When variables are first used, memory is allocated as follows:

Variable Type	Memory Used
Numeric variable	(variable name length + 12) bytes from work area
Character variable	(variable name length + 4) bytes from work area, plus (string length + 1) bytes from character area

Array variables allocated by DIM:

Array Type	Memory Used
Array numeric variable	((variable name length + 4) + (array size × 8) + (dimensions × 2 + 1)) bytes from work area
Array character variable	(variable name length + 4) bytes from work area, plus ((array size) + (dimensions × 2 + 1)) bytes from character area

The current work area size, variable area size, and free space can be checked with the SYSTEM command and the FRE function.

Multiple Statements Per Line

Multiple BASIC statements can be placed on a single line, separated by colons:

10 A = 1 : B = 2 : PRINT A + B

This is equivalent to:

10 A = 1
20 B = 2
30 PRINT A + B

Direct Mode vs Program Mode

• Direct mode: Type a statement without a line number and press EXE. It executes immediately. Useful for quick calculations, checking variable values, and testing commands.
• Program mode: Type statements with line numbers. They are stored in the current program area and executed with RUN.

Most commands work in both modes, but some are restricted to one or the other. Manual commands (like LIST, EDIT, RENUM) can only be used in direct mode. See the Command/Function Table for details.