Changes

* FRAME (CALL &BD19)* Extra, optional 'plotting mode' parameter for DRAW/PLOT commands (supported only through control codes on BASIC 1.0)* GRAPHICS PAPER, GRAPHICS PEN commands* ON BREAK CONT (disable ESCape)* CLEAR INPUT (flush keyboard buffer)* The AUTO command show the whole line if it exist, it only printed a * on the 464 Some parts of 'BASIC' were actually housed in the firmware ROM, but were not officially accessible to other programs. This included the line editor. The 'pure BASIC' parts of Locomotive BASIC - i.e. those not concerned with CPC-specific firmware and hardware features - were upgraded to become Mallard BASIC, the CP/M language shipped with the [[PCW]]. This also featured exceptionally advanced random-access file handling, a feature missing from the CPC. == Command list == === Commands and operators === ==== AFTER I[,t] GOSUB Ln ====: Waits for i/50 seconds and then jumps to the subruotine at line Ln. ==== AUTO [Ln, i] ====: 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.: Example: <pre>AUTO 100,5 - generates line numbers 100, 105, 110...</pre> ==== BORDER color ====: Changes the color of the border. ==== CALL add[,list of parameters] ====: Allows an externally developed subroutine to be called by BASIC: Example: <pre>CALL 0 - resets the computer completely</pre> ==== CAT ====: Displays the names of all existing programes on the tape or disk.: Examples: <pre>CAT [ENTER] - lists all disk files in alpha-numeric orderTAPE [ENTER]CAT [ENTER] - lists names of all tape files in their storage order</pre> ==== CHAIN "filename"[,ln]==== :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. ==== CHAIN MERGE "filename"[,ln][,DELETE1 nl - 1n2]==== :Loads the specified program from tape or disk, 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. ==== CLEAR ====: Clears all variables from memory, leaving the program in memory unchanged. All open files are abandoned. ==== CLG [ink] ====: 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. ==== CLOSEIN ====: Closes any input file (tape or disk). ==== CLOSEOUT ====: Closes any output file (tape or disk). ==== CLS ====: Clears the screen. The text cursor is moved to the upper left corner. ==== CONT ==== : CONTinues program execution interrupted either by [ESC] [ESC] or as a result of STOP within a program. ==== CURSOR ====: [...] ==== DATA x1[,x2,x3...]====: 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. :Example: <pre>10 DATA "Hello, world!", 4220 READ message$:PRINT message$30 READ answer:PRINT "The answer is:";answer</pre> :''See also:'' <tt>READ</tt>, <tt>RESTORE</tt> ==== DEF ====: [...] ==== DEFINT letter range==== : Forces all variables(s) starting with the specified letter(s) to be string variables. The s does not need to be added to DEFSTR variable names. : Example: <pre>10 DEFSTR N - sets all variables starting with letter N as strings.</pre> ==== DEFREAL ====: [...] ==== DEFSTR ==== : Sets the default for variable(s) with the specified first letter(s) to integer. The letter range could be an inclusive range A-Z : Example: <pre>10 DEFINT F,S ..... (or 10 DEFINT A-Z)20 FIRST=111.11:SECOND=22.230 PRINT FIRST,SECOND - prints 111 22</pre> ==== DEG ====: Switch to degrees mode for trigonometric functions (<tt>SIN</tt>, <tt>COS</tt>...). ''See also:'' <tt>RAD</tt> ==== DELETE [line] ====: Deletes the current program completely (without argument) or only the given line. ==== DI ====: Disables interrupts (but not[ESC]) until re-enabled by EI command or by RETURN at end of an interrupts service routine. ==== DIM v[$](i1[,i2]) ==== : Specifies storage space to be allocated for list or table v[$]. i1 is number of rows, i2 is number of columns. If a list or a table is not specified by DIM, i1 and i2 default to 10. ==== DRAW x,y [,[i1][,i2]] ==== : Draws a line from the current cursor position to position x,y. i1 specifies colour, i2 is the logical colour. <pre>i2 = 0 normal colour i2 = 2 AND colouri2 = 1 XOR colour i2 = 3 OR colour</pre> : Example: <pre>CLG 2DRAW 500,400,0 - draws a line from 0,0 to 500,400</pre> ==== DRAWR xr, yr, [[i1][,i2]] ==== : Draws a line from current graphics cursor position to current cursor x position + xr, current cursor y position + yr. i1 and i2 as DRAW.:Example: <pre>Move 200,200DRAWR 100,100,0 - draws a line from 200,200 to 300,300</pre> ==== EDIT line ====: Copies one program line to screen in edition mode. ==== EI ====: Enable interrupts which have been disabled by DI ==== END ====: Indicates end of program ==== ENT ====: [...] ==== ENV ====: [...] ==== ERASE v[$(i1[,i2]) ====: Clears the contents of an array that is no longer required. ==== ERL ==== : Returns the line number of the last error encountered. ==== ERROR i ====: Returns the error message whose error code number is i. ==== EVERY i[,t] GOSUB ln ==== : BASIC branches to the subroutine at line ln every i/50 seconds. ==== FILL i ====: 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. ==== FN ====: [...] ==== FOR TO STEP NEXT ====: [...] ==== FRAME ====: 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. ==== GOSUB i ==== : Jumps to subroutine which is given as argument.: ''Example:'' <pre>10 PRINT "Calling subroutine"20 GOSUB 10030 PRINT "Back from subroutine"40 END100 REM Begin of the subroutine110 PRINT "Subroutine started"120 RETURN</pre> ==== GOTO i ====: Jumps to the line number which is given as argument.: ''Example:''<pre>10 GOTO 10020 REM not executed30 REM not executed100 PRINT "Hello World!"</pre> ==== GRAPHICS ====: [...] ==== IF THEN ELSE ====: [...] ==== INK ====: [...] ==== INPUT ====: [...] ==== KEY ====: [...] ==== LET ====: 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>10 LET a$ = "hello world"20 PRINT a$</pre> ==== LINE ====: [...] ==== LIST ====: [...] ==== LOAD ====: [...] ==== LOCATE x,y ==== : Moves the text cursor to the x,y location.  : x starts at 1 on the left and goes up to 20 (in mode 0), 40 (in mode 1) or 80 (in mode 2). : y starts at 1 at the top and ends at 25 at the bottom. ==== MASK [i1][,i2]==== : Sets bits in each adjacent group of 8 pixel on (1) or off (0) according to binary value of i1 (0-255). i2 determines whether the first point of the line is to plotted (1) or not (0). :Example: <pre>10 CLG 2:MASK 1:MOVE 0,0:DRAW 500,40020 MASK 15:MOVE 0,0:DRAW 500,400</pre> ==== MEMORY add==== : Allocates the amount of memory to be used by BASIC by setting the address of the highest byte it may use. ==== MERGE ====: [...] ==== MID$ ====: [...] ==== MODE ====: Changes the screen mode: MODE 0 is 160x200 in 16 colors, MODE 1 is 320x200 4 colors and MODE 2 is 640x200 2 colors. ==== MOVE x,y [[,i1][,i2]]==== : 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. ==== MOVER ====: [...] ==== NEW ====: [...] ==== ON BREAK CONT ==== : Prevents the interruption of program execution by the ESC key. ==== ON BREAK GOSUB ln ==== : Passes control to subroutine at line ln when ESC ESC pressed. ==== ON BREAK STOP ==== : Restores normal function of ESC key during program execution. ==== ON ERROR GOTO ln ==== : 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. ==== OPENIN "datafile" ==== : Opens the specified data file for reading. ==== OPENOUT "datafile" ====: Opens the specified data file for writing. ==== ORIGIN ====: [...] ==== OUT add,i ==== : Outputs the value of i (0-255) to the I/O address add. ==== PAPER ====: [...] ==== PEN ====: [...] ==== PLOT ====: [...] ==== PLOTR ====: [...] ==== POKE add ==== : Alters contents of memory location add to value i (0-255) ==== PRINT ====: [...] ==== RAD ====: Switch to radians mode for trigonometric functions (<tt>SIN</tt>, <tt>COS</tt>...). : ''See also:'' <tt>DEG</tt> ==== RANDOMIZE [seed] ==== : Resets the pseudo-random generator to the given seed. What is strange is that if no seed is given, one is interactively prompted for. : A common idiom to have a ''random'' random seed is to do: <pre>RANDOMIZE TIME</pre> ==== READ variable ====: 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> ==== RELEASE ====: [...] ==== REM [any text]====: Introduces a comment. ==== RENUM [newLine],[oldLine],[step] ====: Renumbers the lines of the current program. : By default, the whole program is renumbered starting at line 10 with multiples of ten. It is important to note that ''jumps'' (<tt>GOTO</tt>, <tt>GOSUB</tt> and the like) are automatically converted to the new line numbers. : The whole set of parameters can be used to renumber only the last part of a program. : Example: <pre>10 GOTO 2020 GOTO 3030 GOTO 10</pre> : becomes, after calling <tt>RENUM 100,20,5</tt> <pre>10 GOTO 100100 GOTO 105105 GOTO 10</pre> ==== RESTORE [line] ==== : 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. : Example: <pre>10 DATA 10,11,12,13,1420 DATA 20READ i:PRINT i 10ReadyREAD i:PRINT i 11ReadyRESTOREReadyREAD i:PRINT i 10ReadyRESTORE 20ReadyREAD i:PRINT i 20Ready</pre>  : ''See also:'' <tt>DATA</tt>, <tt>READ</tt> ==== RESUME ====: [...] ==== RETURN ==== : Terminates a subroutine and returns control to the line following the GOSUB call (see GOSUB) ==== RUN [line] ====: Runs the current program, optionally starting at a given line. If no line number is given, starts at the first line. ==== SAVE ====: [...] ==== SOUND ====: [...] ==== SPC ====: [...] ==== SPEED ====: [...] ==== SQ (channel) ==== : Returns a bit significant integer showing state of the sound queue for specified channel where channel 1,2,3, = A, B, C :Bits 0,1 and 2 Number of free entries in the queue:Bits 3,4 and 5 Redezvous state at head of the queue:Bit 6 Head of the queue is held:Bit 7 Channel is currently active ==== STOP ==== : Breaks program execution at line containing the STOP statement. The message '''BREAK in''' is output with the line number. ==== SUB ====: [...] ==== SWAP ====: [...] ==== SYMBOL n,i1[,i2,i3,i4,i5,i6,i7,i8] ==== : Redefines the appearance of the character at index n.: Each of the following eight integers defines the contents of one pixel row, starting at the top of the character.: Each character fits in an 8x8 pixel grid.: Missing lines are considered as empty. : Example: <pre>SYMBOL 255,255,129,129,129,129,129,129,255PRINT CHR$(255)</pre> : Defines character 255 to look like an empty square and prints it. : Initially, only characters with indices ranging from 240 to 255 can be redefined.: See also <tt>SYMBOL AFTER</tt> to allow redefinition of arbitrary characters. ==== SYMBOL AFTER n ====: Allows the redefinition of character symbols from index n included.  : Symbol redefinitions are made using the SYMBOL command above.: Initially, only symbols from index 240 to 255 can be redefined. This initial situation can be restored with <tt>SYMBOL AFTER 240</tt>. Symbol previously redefined are restored to their original appearance. ==== TAB ====: [...] ==== TAG [#st] ==== : Allows text to print at graphics cursor position.: see TAGOFF ==== TAGOFF [#st] ==== : Directs text to stream st printing it at previous text cursor position. ==== TROFF ==== : Turns off the program flow trace (see TRON) ==== TRON ==== : Turns on the program flow trace for debugging. Causes the line number of each statement executed to be displayed. ==== USING ====: [...] ==== WAIT add, i1[,i2] ==== : Waits until the I/O port at add returns a value (0-255). The value returned is XORed with i2 and the ANDed with i1. This is repeated until a non-zero result occurs. ==== WHILE WEND ====: [...] ==== WIDTH ====: [...] ==== WINDOW ====: [...] ==== WRITE [#st,] v[$], v[$] ==== : Writes the values of the specified variable to the specified stream. : Example: <pre>10 OPENOUT "DUMMY"20 INPUT A$,A30 WRITE #9,A$,A40 CLOSEOUT</pre> ==== ZONE i==== : Changes the width of the print zone. Default is 13. === Operators === ==== AND ====: [...] ==== MOD ====: [...] ==== NOT ====: [...] ==== OR ====: [...] ==== XOR ====: [...] === Functions === ==== ABS (n) ====: Returns the absolute value of n by ignoring the sign value. : Example <pre>PRINT ABS(-3.5) - prints 3.5</pre> ==== ASC (s) ==== : Returns ASCII code number of first character of string s ==== ATN (n) ====: Returns the arctangent of n. ==== BIN$ (i1,[i2]) ====: 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>PRINT BIN$(66,8) - prints 01000010</pre> ==== CHR$ (n)====: Returns the character for a given index n. For instance CHR$(65) returns the character 'A'. Valid indices range from 0 (zero) to 255. : As an example, try the following basic program : <pre>10 print chr$(208+rnd(2));:goto 10</pre> : It will draw a random maze with characters 208 and 209, which are an horizontal and a vertical bar. ==== CINT (n) ==== : Returns rounded up integer value of n between -32768 and 32767. : Example: <pre>PRINT CINT(3.8) - print 4</pre> ==== COPYCHR$ (st) ==== : Copies character from current position in specified stream. ==== COS (n) ==== : Returns cosine of n in degrees or radians (se DEG and RAD) ==== CREAL (n) ==== : Converts integer n to real numeric variable. ==== DEC$(n, format) ==== : Retruns the decimal string representation of n, according to the specified format (see PRINT USING) ==== DERR ==== : Gives the most recent error code number returned by [[Amsdos]]. ==== EOF ==== : Checks to see if end of specified file has been reached during input. Returns 0 (false) until the end of file, then -1 (true) ==== ERR ==== : Returns the error code number of the last error encountered. ==== EXP (i) ==== : Returns the result of calculating e to the power i. : Example: <pre>PRINT EXP(1) - prints 2.71828183</pre> ==== FIX (n) ==== : Removes the fractional part of n (see INT) ==== FRE (n/se) ==== : Returns the amount of unused memory, irrespective of the nature or value of the dummy argument inside the bracket. : Examples: <pre>PRINT FRE(o) or PRINT FRE("hello")</pre> ==== HEX$ (i1, i2) ==== : Returns a string hexadecimal digit representation of i1 (0-65535). The number of hex digits in the string is given by i2 (0-15) ==== HIMEM ==== : Returns address of the highest memory address used by BASIC. ==== INKEY (i) ====: Checks to see if key number i is being pressed. <pre>Value returned [SHIFT] [CTRL] Specified key-1 ignored ignored up0 up up down32 down up down128 up down down160 down down down</pre> ==== INKEY$ ==== : 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. ==== INP (add) ==== : Returns value read from the I/O address add ==== INSTR ====: [...] ==== INT (n) ==== : As in FIX if n is positive; if n is negative, it rounds it down. : Example: <pre>PRINT INT(3.99), INT(-3.99) - prints 3 -4</pre> ==== JOY (i) ==== : Returns bit-significant value from specified joystick. i = 0 or 1. <pre>Bit Value returned0(up) 11(down) 22(left) 43(right) 84(fire 2) 165(fire 1) 32</pre> ==== LEFT$ (se, i) ==== : Returns a substring of se. The substring begins at the left-most character of se and contains i characters. : Example: <pre>A$="ABCDEFG":PRINT LEFT$(A$,3) - prints ABC</pre> ==== LEN (se) ==== : Returns the number of characters in se (0 - 255) ==== LOG (n) ==== : Returns the natural logarithm (to base e) of n. ==== LOG10 (n) ==== : Returns the logarithm to base 10 of n. ==== LOWER$ (se) ==== : Returns a copy of se in which all alphabetical characters are converted to lower case (see also UPPER) : Example <pre>PRINT LOWER$("A1B2c3") - print a1b2c3</pre> ==== MAX (list of n) ==== : Returns the maximum value from the given list. : Example: <pre>PRINT MAX(3,8,25,1,2,9) - prints 25</pre> ==== MIN (list of n) ==== : Returns the minimum value from the given list (see MAX) ==== PEEK (add) ==== : Returns the contents of the specified memory location (0-65535) ==== PI ==== : Returns value of PI (3.14159265) ==== POS (#st) ==== : Returns column number of print position relative to left edge of text window on stream st. st must be specified. : Example: <pre>PRINT POS(#0) - prints 1</pre> ==== REMAIN (i) ==== : Returns count remaining in delay timer i (0-3) then disables it. ==== RIGHT$ (se,i) ==== : Returns a substring of length i (0-255) characters from se, ending at the rightmost character of se. : Example <pre>PRINT RIGHT$("ABCDEFG",3) - prints EFG</pre> ==== RND [(n)] ====: Generates the next random number in the current squence if n is positive or omitted. If n = 0, the random number generated will be the same as the last random number generated. ==== ROUND (n[,i1]) ==== : Rounds n to a number of decimal places or to the power of ten specified by i. If i is negative, the n is rounded to give an absolute integer with i zeros before the decimal point.: Example: <pre>PRINT ROUND(1562.357,2):PRINT ROUND(1562.375,-2) - prints 1562.36 1600</pre> ==== SGN (n) ====: Returns 1 if n is positive, 0 if n = 0, -1 if n is negative. ==== SIN (n) ====: Returns sine of n in degree or radian mode (see DEG and RAD) ==== SPACE$(i) ==== : Creates a string containing i spaces (0-255) ==== SQ (channel) ====: Returns a bit significant integer showing state of the sound queue for specified channel where channel 1, 2, 3 = A, B, C.<pre>Bits 0,1 and 2 number of free entries in the queueBits 3,4 and 5 redezvous state at head of the queueBit 6 head of the queue is heldBit 7 channel is currently active</pre> ==== SQR (n) ====: Returns the square root of n. ==== STR$(n) ==== : Returns the string representation of number n. ==== STRING$ ==== : Returns i copies of the string character specified by s. : Example: <pre>PRINT STRING$(3,"*") - prints ***</pre> ==== TAN (n) ==== : Returns the tangent of n. The DEG and RAD commands can be used to force the result to either mode. ==== TEST (x,y) ==== : Moves the graphics cursor by x and y and returns the value of the ink at that position. ==== TESTR (x,y) ==== : Moves the graphics cursor by x and y relative to its current position and returns the value of ink at that position. ==== TIME ====: Returns time elapsed since the computer was switched on or reset.: One second = TIME/300. ==== UNT (add) ==== : Returns an integer(-32768 to 32767) which is the two's complement of add. : Example: <pre>PRINT UNT(&FF66) - prints -154</pre> ==== UPPER$(se) ==== : Gives copy of se with all alphabetic characters in upper case. ==== VAL(se) ==== : Returns the numeric value (including signs) of first numeric character(s) in se. Returns 0 if se starts with a non-number. : Example: <pre>PRINT VAL("-12.34x", VAL("A-12") - prints -12.34 0</pre> ==== VPOS (#st) ====: Reports the current row (line) position of the text cursor relative to the top of the text windows of the specified stream. ==== XPOS ==== : Returns the current horizontal (x) position of the graphics cursor. ==== YPOS ==== : Returns the current vertical (y) position of the graphics cursor.  ''(Please, fill in. Looks like a lot of work ;-) ...)'' == Error codes == * 1 '''Unexpected NEXT''' - Occurs when the FOR of a FOR .. NEXT loop is missing.* 2 '''Syntax Error''' - Typing error or incorrect punctuation.* 3 '''Unexpected RETURN''' - Caused by entering a subroutine other than with GOSUB.* 4 '''DATA exhaused''' - Trying to READ data when data pointer has reached end of data.* 5 '''Improper argument''' - The argument for a function is not legal (eg. PRINT SQR(--10)).* 6 '''Overflow''' - The computer cannot handle a number greater than 1.7E38.* 7 '''Memory full''' - All available RAM is being used or has been reserved. Program to big or control structures too deeply nested.* 8 '''Line does not exist''' - Attempt to RUN, GOTO or GOSUB a non-existent line number.* 9 '''Subsript out of range''' - Value of a subscript in an array is greater than DIM declaration.* 10 '''Array already dimensioned''' - Arrays can only be DIMensioned once within a program.* 11 '''Division by zero''' - Trying to divide a number by zero.* 12 '''InvalidDirect command''' - Using a statement as a direct command it is not allowd outside a program.* 13 '''Type mismatch''' - Trying to assign string data to a numeric variable or vice versa.* 14 '''String space full''' - String memory area is full.* 15 '''String to long''' - String may not exceed 256 characters.* 16 '''String expression too complex''' - A string expression need to be broken down into smaller expressions.* 17 '''CannotCONTinue''' - CONT can only be used if program was stopped by [ESC] or a STOP in program - not after END.* 18 '''Unknown user function''' - A DEF FN must be executed before calling an FN function.* 19 '''RESUMEmissing:''' - End of program has been reached while in error processing mode. Use ON ERROR before RESUME.* 20 '''UnexpectedRESUME''' - RESUME is only used in error processing mode, ON ERROR GOTO statement must be used first.* 21 '''Direct Command found''' - A line without a line number has found while loading a file.* 22 '''Oprand missing''' - An incomplete expression has been found.* 23 '''Line too long''' - The line contains to many statements.* 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).* 26 '''NEXT missing''' - The NEXT of a FOR ... NEXT loop is missing.* 27 '''File already open''' - Trying to open an open file. Use CLOSEIN or CLOSEOUT first.* 28 '''Unknown command''' - Given when an unknown command follows a masterspace.* 29 '''WEND missing''' - The WEND part of the WHILE ... WEND loop is missing.* 30 '''UnexpectedWEND''' - WEND encountered without a corresponding active WHILE.* 31 '''File not open''' - Attempting to read from or write to a file without OPENing it first. == Other Basic Dialects avaliable for the CPC == *[[BBC Basic]]*[[C BASIC Compiler|C BASIC]]*[[E-BASIC]] == Web links == * [http://www.kjthacker.f2s.com/docs/bastech.html Technical information at the Unofficial Amstrad WWW Resource]* [http://www.sean.co.uk/books/amstrad/bforbasic.shtm Locomotive Basic Tutorial by Sean McManus] [[Category:Programming]]