Changes

=== Commands and operators ===

: Automaticaly generates line numbers starting at line Ln with increment i between line numbers.

: Use [ESC to leave AUTO mode. Default value for Ln and i is 10.

</pre>

: Changes the color of the border.

: Allows an externally developed subroutine to be called by BASIC

: Example:

</pre>

: Displays the names of all existing programes on the tape or disc.

: Examples:

:Enables the specified program to be loaded and RUN automatically. If the optional parameters ln is specified, the program execution will commence from line ln.

:Loads the specified program from tape or disc, merges it into the program in memory, and starts execution of the merged program. The parameter DELETE1n1 - 1n2 is used to delete part of the original program before running it, if required.

: Clears all variables from memory, leaving the program in memory unchanged. All open files are abandoned.

: Clears the graphics screen to colour specified by ink. If parameter ink is not specified them the graphics screen is cleared to the colour specified by the GRAPHICS PAPER statement.

: Closes any input file (tape or disc).

: Closes any output file (tape or disc).

: Clears the screen. The text cursor is moved to the upper left corner.

: CONTinues program execution interrupted either by [ESC] [ESC] or as a result of STOP within a program.

: [...]

: Defines a data ''section'' to be used by <tt>READ</tt> calls.

: Data values can be of any type (integer, real or string) as long as the corresponding <tt>READ</tt> calls use a variable of the right type.

:''See also:'' <tt>READ</tt>, <tt>RESTORE</tt>

: [...]

: Forces all variables(s) starting with the specified letter(s) to be string variables. The s does not need to be added to DEFSTR variable names.

</pre>

: [...]

: Sets the default for variable(s) with the specified first letter(s) to integer. The letter range could be an inclusive range A-Z

</pre>

: Switch to degrees mode for trigonometric functions (<tt>SIN</tt>, <tt>COS</tt>...).

''See also:'' <tt>RAD</tt>

: Deletes the current program completely (without arguments) or only the given line or line range. Even

: <code>DELETE -</code>

: The lines specified do not have to exist, all lines matching the range will be deleted and having no matches does not cause an error.

: Disables interrupts (but not[ESC]) until re-enabled by EI command or by RETURN at end of an interrupts service routine.

: Creates array <code>a</code> with single or multiple dimensions. You may optionally specify integer (<code>%</code>), real (<code>!</code>) or string (<code>$</code>) type otherwise it defaults to the current type set for the first letter of the array name. <code>d1</code> is size of first dimension-1, <code>d2</code> is size of second dimension-1 and so on. <code>DIM x(10)</code> will create an array with 11 elements, <code>x(0)</code> is the first element, <code>x(10)</code> is the eleventh and last. You can specify as many dimensions as will fit on one 255 character line, which is a maximum of 125. Trying to create an array that already exists will generate an <code>Array already dimensioned</code> error. If an array is not specified by <code>DIM</code> before being accessed, each dimension value defaults to 10. The maximum dimensions that can be created this way is three.

: Draws a line from the current cursor position to position x,y. i1 specifies colour, i2 is the drawing style.

</code>

: Draws a line from current graphics cursor position to current cursor x position + xr, current cursor y position + yr. i1 and i2 as DRAW.

</pre>

: Copies one program line to screen in edition mode.

: Enable interrupts which have been disabled by DI

: Indicates end of program

: [...]

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: Erases the specified array(s) and frees the memory used. Must specify existing array(s) or an <code>Improper argument</code> error will be generated.

: Returns the line number of the last error encountered.

: Returns the error message whose error code number is i.

: BASIC branches to the subroutine at line ln every i/50 seconds.

: Fills an area of a graphics screen i colour i (0-15). Default value of i is the current graphics pen colour. Only available in Basic 1.1.

: [...]

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: Smooths character and graphics movement and reduces flicker (waits for a VSYNC signal). Only available in Basic 1.1. On a CPC 464 you can use CALL &BD19 instead.

: Jumps to subroutine which is given as argument.

</pre>

: Jumps to the line number which is given as argument.

: ''Example:''

</pre>

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: Used to define variables. You don't need to use the ''LET'' command because it is just a command which was added for compatibility reasons.

: ''Example:''

</pre>

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: Moves the text cursor to the x,y location.

: y starts at 1 at the top and ends at 25 at the bottom.

: Sets bits in each adjacent group of 8 pixel on (1) or off (0) according to binary value of i1 (0-255). i2 determines whether the first point of the line is to plotted (1) or not (0).

</pre>

: Allocates the amount of memory to be used by BASIC by setting the address of the highest byte it may use.

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: Changes the screen mode: MODE 0 is 160x200 in 16 colors, MODE 1 is 320x200 4 colors and MODE 2 is 640x200 2 colors.

: Moves the graphic cursor to position x,y. The parameter i1 may be used to change the pen (drawing) colour. The parameter i2 specifies the logical colour, as in DRAW.

: [...]

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: Prevents the interruption of program execution by the ESC key.

: Passes control to subroutine at line ln when ESC ESC pressed.

: Restores normal function of ESC key during program execution.

: Passes the control to line ln if an error is detected in the program.

: ON ERROR GOTO 0, Turns of the error trap, and restores normal error processing.

: Opens the specified data file for reading.

: Opens the specified data file for writing.

: [...]

: Outputs the value of i (0-255) to the I/O address add.

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: Alters contents of memory location add to value i (0-255)

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: Switch to radians mode for trigonometric functions (<tt>SIN</tt>, <tt>COS</tt>...).

: ''See also:'' <tt>DEG</tt>

: Resets the pseudo-random generator to the given seed. What is strange is that if no seed is given, one is interactively prompted for.

</pre>

: Gets the next data item (from <tt>DATA</tt> commands), stores it in the given variable and moves to the next item.

The variable must be of the correct type.

''See also:'' <tt>DATA</tt>, <tt>RESTORE</tt>

: [...]

: Introduces a comment.

: Renumbers the lines of the current program.

</pre>

: Resets the data pointer used by <tt>READ</tt>. When used without parameters, resets the pointer to the first data in the program. Otherwise, resets the pointer to the given line number.

: ''See also:'' <tt>DATA</tt>, <tt>READ</tt>

: [...]

: Terminates a subroutine and returns control to the line following the GOSUB call (see GOSUB)

: Runs the current program, optionally starting at a given line. If no line number is given, starts at the first line.

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: Returns a bit significant integer showing state of the sound queue for specified channel where channel 1,2,3, = A, B, C

:Bit 7 Channel is currently active

: Breaks program execution at line containing the STOP statement. The message '''BREAK in''' is output with the line number.

: [...]

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: Redefines the appearance of the character at index n.

: See also <tt>SYMBOL AFTER</tt> to allow redefinition of arbitrary characters.

: Allows the redefinition of character symbols from index n included.

: Initially, only symbols from index 240 to 255 can be redefined. This initial situation can be restored with <tt>SYMBOL AFTER 240</tt>. Symbol previously redefined are restored to their original appearance.

: [...]

: Allows text to print at graphics cursor position.

: see TAGOFF

: Directs text to stream st printing it at previous text cursor position.

: Turns off the program flow trace (see TRON)

: Turns on the program flow trace for debugging. Causes the line number of each statement executed to be displayed.

: [...]

: Waits until the I/O port at add returns a value (0-255). The value returned is XORed with i2 and the ANDed with i1. This is repeated until a non-zero result occurs.

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: Writes the values of the specified variable to the specified stream.

</pre>

: Changes the width of the print zone. Default is 13.

=== Operators ===

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=== Functions ===

: Returns the absolute value of n by ignoring the sign value.

</pre>

: Returns ASCII code number of first character of string s

: Returns the arctangent of n.

: Returns binary representation of i1 between -32768 and 65535. The number of binary digits (0s and 1s) is specified by i2 (0-16)

: Example:

</pre>

: Returns the character for a given index n. For instance CHR$(65) returns the character 'A'. Valid indices range from 0 (zero) to 255.

: It will draw a random maze with characters 208 and 209, which are an horizontal and a vertical bar.

: Returns rounded up integer value of n between -32768 and 32767.

</pre>

: Copies character from current position in specified stream.

: Returns cosine of n in degrees or radians (se DEG and RAD)

: Converts integer n to real numeric variable.

: Retruns the decimal string representation of n, according to the specified format (see PRINT USING)

: Gives the most recent error code number returned by [[Amsdos]].

: Checks to see if end of specified file has been reached during input. Returns 0 (false) until the end of file, then -1 (true)

: Returns the error code number of the last error encountered.

: Returns the result of calculating e to the power i.

</pre>

: Removes the fractional part of n (see INT)

: Returns the amount of unused memory, irrespective of the nature or value of the dummy argument inside the bracket.

</pre>

: Returns a string hexadecimal digit representation of i1 (0-65535). The number of hex digits in the string is given by i2 (0-15)

: Returns address of the highest memory address used by BASIC.

: Checks to see if key number i is being pressed.

</pre>

: Checkts the keyboard and returns the string character of the key pressed. The string character returned is normally assigned to a string variable. If no key pressed, a null string is returned.

: Returns value read from the I/O address add

: [...]

: As in FIX if n is positive; if n is negative, it rounds it down.

</pre>

: Returns bit-significant value from specified joystick. i = 0 or 1.

</pre>

: Returns a substring of se. The substring begins at the left-most character of se and contains i characters.

</pre>

: Returns the number of characters in se (0 - 255)

: Returns the natural logarithm (to base e) of n.

: Returns the logarithm to base 10 of n.

: Returns a copy of se in which all alphabetical characters are converted to lower case (see also UPPER)

</pre>

: Returns the maximum value from the given list.

</pre>

: Returns the minimum value from the given list (see MAX)

: Returns the contents of the specified memory location (0-65535)

: Returns value of PI (3.14159265)

: Returns column number of print position relative to left edge of text window on stream st. st must be specified.

</pre>

: Returns count remaining in delay timer i (0-3) then disables it.

: Returns a substring of length i (0-255) characters from se, ending at the rightmost character of se.

</pre>

: Generates the next random number in the current squence if n is positive or omitted. If n = 0, the random number generated will be the same as the last random number generated.

: Rounds n to a number of decimal places or to the power of ten specified by i. If i is negative, the n is rounded to give an absolute integer with i zeros before the decimal point.

</pre>

: Returns 1 if n is positive, 0 if n = 0, -1 if n is negative.

: Returns sine of n in degree or radian mode (see DEG and RAD)

: Creates a string containing i spaces (0-255)

: Returns a bit significant integer showing state of the sound queue for specified channel where channel 1, 2, 3 = A, B, C.

<pre>

</pre>

: Returns the square root of n.

: Returns the string representation of number n.

: Returns i copies of the string character specified by s.

</pre>

: Returns the tangent of n. The DEG and RAD commands can be used to force the result to either mode.

: Moves the graphics cursor by x and y and returns the value of the ink at that position.

: Moves the graphics cursor by x and y relative to its current position and returns the value of ink at that position.

: Returns time elapsed since the computer was switched on or reset.

: One second = TIME/300.

: Returns an integer(-32768 to 32767) which is the two's complement of add.

</pre>

: Gives copy of se with all alphabetic characters in upper case.

: Returns the numeric value (including signs) of first numeric character(s) in se. Returns 0 if se starts with a non-number.

</pre>

: Reports the current row (line) position of the text cursor relative to the top of the text windows of the specified stream.

: Returns the current horizontal (x) position of the graphics cursor.

: Returns the current vertical (y) position of the graphics cursor.

== Error codes ==

* 2 '''Syntax Error''' - Typing error or incorrect punctuation.

* 11 '''Division by zero''' - Trying to divide a number by zero.

* 14 '''String space full''' - String memory area is full.

* 21 '''Direct Command found''' - A line without a line number has found while loading a file.

* 24 '''EOF met''' - Trying to input data beyond end of data file.

* 25 '''FILE type error''' - Using a program file instead of a data file to read or write (or vice versa).

== Other Basic Dialects available for the CPC ==