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GFA BASIC ver. 2.0 Quick Reference The following list illustrates the GFA BASIC 2.0 command syntax with required parameters. Command line parameters placed betweeen brackets [ ] are optional. Source: GFA BASIC Reference Card, Copyright 1988 MichTron, Inc. VARIABLE NAMES A variable must begin with a letter, but may consist of any combination of letters and numbers, up to a maximum length of 255 characters. TYPES OF VARIABLES var Real variable, a six-byte floating point value, accurate to 11 decimal places. In Scientific Notation, exponents of up to 154 are permitted. var% Integer variable, a four byte value representing a whole number between -2147483648 and +2147483647. var! Boolean variable. Requires 2 bytes for storage and may only represent TRUE(-1) or FALSE(0) values. var$ String variable. May contain up to 32,767 alpha- numberic characters. ARRAY VARIABLES var(i) One dimension real array. var%(i) One dimension integer array. var!(i) One dimension Boolean array. POINTERS *var Real pointer. *var% Integer pointer. *var! Boolean pointer. *var$ String pointer. *var() Array pointer. CONSTANTS ADDRIN Addr of AES address input block. ADDROUT Addr of AES address output block. BASEPAGE Addr of the basepage of GFA BASIC. CONTRL Addr of VDI control block. FALSE 0 GB Addr of start of AES. GCONTROL Addr of AES control block. GINTIN Addr of AES integer input block. GINTOUT Addr of AES integer output block. HIMEM Addr of first byte after GFA BASIC. INTIN Addr of VDI integer input block. INTOUT Addr of VDI integer output block. PI 3.1415926536 PTSIN Addr of VDI point input block. PTSOUT Addr of VDI point output block. TRUE -1 VDIBASE Addr of GEM storage area used by GFA BASIC. WINDTAB Addr of window parameter table. OPERATORS () Parenthesis. + Assign possitive value (plus sign). - Assign negatie value (minus sign). ^ Exponent (raise to a power). A*B Floating point multiplication. A+B Real and integer addition. A-B Real and integer subtraction. A/B Floating point division. A<B Less than. A<=B Less than or equal to. A<>B Not equal to. A=B Equal in value. A>B Greater than. A>=B Greater than or equal to. A$+B$ String concatenation. AND Logical conjunction, bit-wise operation. DIV Integer division. EQV Logical equivalence. IMP Logical implication. MOD Returns remainder from integer division. NOT Logical negation, bit wise operation. OR Logical comparison, bit wise operation. XOR Logical exclusive OR, bit wise operation. MATHEMATICAL FUNCTIONS ABS(x) Returns the absolute value. ADD x,y Increases the value of x by y (addition). ATN(r) Calculates arc-tangent of an angle in radians. COS(n) Calculates the cosine of a number in radians. DEC x,y Decrements x by y. DIV x,y Divides x by y. EVEN(x) Returns a -1 value for an even number; otherwise returns 0. EXP(n) Calculates value of an exponent. FIX(x) Returns the integer portion of a value. FRAC(x) Returns the fractional portion of a value. INC x Increments x by 1. INT(x) Returns the integer portion of a value. LOG(x) Returns the natural logarithm of a value. LOG10(x) Returns the base 10 logarithm of a value. MUL x,y Multiplies x by y. ODD(x) Returns a -1 value for an odd number; otherwise returns 0. RANDOM(x) Returns a random integer number between 0 and x. RND(dummy) Returns a random value between 0 and 1. SGN(x) Determines the sign of a value (1, -1 or 0). SIN(angle) Calculates the sine in radians of a number. SQR(n) Calculates square root. SUB x,y Decreases x by y. TAN(angle) Calculates the tangent of an angle in radians. TRUNC(x) Returns the integer portion of a value. VOID expr Calls function without returning a value. SYSTEM COMMANDS CLEAR Clears all variables and arrays. CLR [var,var...] Deletes variables. CONT Resumes program execution. DEFLIST 1 Defines listing format. In this case, commands, functions and variable names are written with the first letter capitalized. DEFLIST 0 Defines listing format. In this case, commands and function names are written in all capital letters. EDIT Terminates program and returns to the editor. END Closes all files and terminates program. ERASE(field) Deletes an array and releases dimensioned area. LIST Stores program presently in memory on a disk in ASCII format. LIST "CON:" Displays listing of the program currently in memory on the output screen. LIST "file.lst" Stores program currently in memory on a disk in ASCII format as "file.lst". LLIST Sends listing of program to an attached printer. NEW Removes program from memory. QUIT Terminates program and returns to GEM Desktop. REM,',! Enables remarks to be included in a program. RUN Immediate mode command. Executes a program in memory. STOP Stops a program. SYSTEM Terminates program and returns to GEM Desktop. TROFF Disables trace mode. TRON Enables trace mode. PROGRAM CONTROL Looping Structures FOR var=a [DOWN]TO b [STEP c] statement NEXT var GOTO label DO statement LOOP REPEAT statement UNTIL condition WHILE condition statement WEND IF condition [THEN] statement [ELSE] statement ENDIF EXIT IF condition Subroutine (Procedure) Controls PROCEDURE name LOCAL a,b,c Declares variable to be valid only in this subroutine. statement statement RETURN GOSUB name ON expr GOSUB name Functions DEFFN name [(list)]=expr DEFFN name$[(list)]=string expr FN name[(expr[,expr...])] FN name$[(expr[,expr...])] STRING COMMANDS &H Precedes hexadecimal value. &O Precedes octal value. &X Precedes binary value. ASC(a$) Returns the ASCII code of the first character in a string. BIN$(a) Transforms a value into a character string expression in binary (base 2) form. CHR$(i) Returns the character which corresponds to the ASCII value of i. CVD(a$) Converts an 8-byte character string in MBASIC format into a number. CVF(a$) Converts a 6-byte character string in GFA BASIC format into a number. CVI(a$) Converts a 2-byte character string into a 16-bit integer value. CVL(a$) Converts a 4-byte character string into a 32-bit integer value. CVS(a$) Converts a 4-byte Atari BASIC character string into a 32-bit integer value. FRE(0) Returns free storage space in bytes. HEX$(a) Converts a value into a character string expression in hexadecimal (base 16) form. INSTR(a$,b$[,n]) Returns the position of a specified character within a string. INSTR([n,]a$,b$) Returns the position of a specified character within a string. LEFT$(a$,n) Returns all characters beginning with the nth character from the left side of a string. LEN(a$) Returns the length fo a string. LSET var=string Left justifies a string. MID$(a$,n1[,n2]) Returns the character(s) from the position(s) specified by n1 and n2 from within a string. MID$(a$,n1[,n2])=b$ Inserts a specified character or group of characters into a string, at the positions specified by n1 and n2. MKD$(i) Converts a number into MBASIC-compatible 8-byte format. MKF$(i) Converts a number into GFA BASIC 6-byte format. MDI$(i) Converts a 16-bit integer into a 2-byte string. MKL$(i) Converts a 32-bit integer into a 4-byte string. MKS$(i) Converts a number into an Atari BASIC compatible 4-byte format. OCT$(a) Converts a value into a character string expression in octal (base 8) form. RIGHT$(a$,n) Returns all characters beginning with the nth character from the right side of a string. RSET var=string right justifies a string. SPACE$(n) Creates a string of n spaces. STR$(a) Converts a decimal value into a character string. STRING$(n,"c") Creates a string of n characters specified by the included string. STRING$(n,c) Creates a string of n characters specified by the ASCII code c. UPPER$(a$) Converts a string to all upper case characters. VAL(a$) Returns the numerical value of the first character in a string. VAL?(a$) Returns the number of characters in a string which can be converted into a numerical value. FIELDS AND POINTERS ARRAYFILL FIELD(),N Assigns the value n to all elements in an array. ARRPTR(var) Returns the address of the descriptor of a string or array. DIM(a$,x) Sets dimensions of an array or arrays. DIM?(field) Returns the number of elements in an array. MAX(expr) Returns the greatest value from a list of expressions. MIN(expr) Returns the least value from a list of expressions. OPTION "Text" Passes control commands to the GFA Compiler. OPTION BASE 0 Sets the lower limit of an array to zero. OPTION BASE 1 Sets the lower limit of an array to one. SWAP *ptr,fvar() Exchanges the elements in the field pointed to by *ptr with the elements in the array fvar(). SWAP fvar1(),fvar2() Exchanges the values of the elements in the array fvar1() with the elements of fvar2(). SWAP var1,var2 Exchages values of var1 with var2. TYPE(*var) Returns the type of variable at which the pointer is set: -1=Error 0=Real 1=String 2=Integer 3=Boolean 4=Real array 5=String array 6=Integer array 7=Boolean array VARPTR(var) Returns the address or starting address of a variable. ASSIGNMENT FUNCTIONS DATA list,list,... Holds data items, or a list of data items, which may be placed into a variable or an array by using the READ function. [LET] var=expr Assigns the value of an expression to a variable. READ var Reads values from a DATA statement and assigns them to a variable, var. RESTORE [label] Places the DATA pointer at the beginning of the program, or after the label specified. INPUT AND OUTPUT CRSCOL Determines the cursor column. CRSLIN Determines the cursor row. DEFNUM n Rounds all numbers to n digits before output. FORM INPUT Permits the input of a character string during program execution. FORM INPUT n AS a$ Permits a character string to be changed during program execution. n is the max length of the string variable. HARDCOPY Sends screen contents to an attached printer. (Same as pressing the <Alternate><Help> combination.) INKEY$ Reads a character from the keyboard. INP(n) Reads one byte at a time from an input device. 0 = LST: (printer) 1 = AUX: (RS-232) 2 = CON: (keyboard) 3 = MID: (MIDI port) INP?(n) Determines input status of specified peripheral device (as shown above). INPUT Permits information to be entered from the keyboard during program execution. INPUT# Permits information to be entered from a specified channel during program execution. INPUT$(len,a$) Reads len characters from the keyboard or from a file. LINE INPUT Permits a string to be entered during program execution. LINE INPUT# Permits a string to be entered from a specified channel during program execution. LPOS(n) Returns the column where the printer head is located. OUT n,c Transfers one byte to a specified output device: 0 - 3 (same as above) 4 = IKB: (Intelligent keyboard; use with caution) 5 = VID: (Screen) OUT?(n) Returns status of specified output device. POS(dummy) Returns the column in which the cursor is located. PRINT or LPRINT or PRINT # Displayes information of the screen or specified data channel. AT(x,y) Prints at a position specified by the curosor column and row. TAB(n) Moves cursor position to the nth column. SPC(n) Prints a number of spaces specified by n. ; Carriage return/line feed suppressed after printing. , Carriage return/line feed suppressed. Cursor positioned at intervals of 16 columns. ' One space is left in for each apostrophe. PRINT USING Formatted output of digit and character strings. Format Description # Reserves spaces for digits. . Positions decimal point. + Prints plus sign. - Reserves space for minus sign. * Reserves space for digits, but prints * if reserved digit is not used. $$ or $ Prefix $. , Inserta a comma. ^^^^ Displaya in exponential form. ! Indicates first character of a string is printed. & Whole string is printed. \..\ As many characters are printed as there are characters between the \\. _ Treats next character in the format string as a character, rather than as a format character. WRITE Outputs data to the screen. WRITE# Stores data in a sequential file. SEQUENTIAL AND RANDOM DATA CLOSE#n Closes a data channel. EOF(#n) Determines whether the file pointer has reached the end of the file. FIELD #n,expr AS a$ [,expr2 AS a2$...] Divides a record into arrays. GET #n Reads a record from a random acess file. INP(#n) Reads one byte of data from a file on data channel n. INPUT#n Obtains data from file on channel n. INPUT$(i) Reads a specified number of character from the keyboard. LINE INPUT#n,a$ Obtains data from channel n. LOC#n Returns the location of the file pointer for the fifle with the channel number n. LOF(#n) Returns the length of the file with the channel number n. OPEN "mode" [#]n,"file name"[,len] Opens a data channel to a disk. Mode Open for A Append I Input O Output R Random access U Reading and writing OUT#n,c Transfers one byte of data to a file on data channel n. PRINT#n Sends data to a file on data channel n. PUT#n Writes a record to a random access file. RELSEEK#n,x Moves the file pointer x bytes in a file with the channel number n. SEEK#n,x Sets file pointer on the xth byte of the file associated with channel number n. WRITE#n Stores data in a sequential file. GENERAL DISK COMMANDS BGET #n,adr,len Reads from a specified data channel directly into memory. BLOAD "file",adr Loads a disk file directly to a specified area of memory. BPUT #n,adr,len Writes a specified area of memory directly to disk. BSAVE "file",adr,len Saves a specified area of memory to disk. CHAIN "file.bas" Loads a program file into memory and starts the program. EXEC(flag,"file",cmd,env) Loads and executes machine language or compiled programs from disk. EXIST("file.ext") Determines whether a specified file is present on the disk (-1 if present, 0 if not present). KILL "file" Deletes a disk file. LIST "file.lst" Saves a file to disk in ASCII format. LOAD "file" Loads a file into memory. NAME "oldfile" AS "newfile" Renames a file as specified. PSAVE "file" Saves a file in protected format. SAVE "file" Saves a file to disk. DIRECTORY FUNCTIONS CHDIR "name" Changes directories. CHDRIVE n Sets the default disk drive. DFREE(n) Returns the amount of free storage space on the specified disk. DIR ["A:\*.*"] Lists files on a disk. DIR$(n) Returns the name of the active directory for drive number n. FILES ["A:\*.*"] Lists files on a disk. FILESELECT "filespec","filename",x$ Calls the GEM file selector box. MKDIR "name" Creates a new directory. RMDIR "name" Removes a directory folder. GRAPHICS COMMANDS BITBLT s%(),d%(),p%() Raster copying command. BMOVE src,dest,cnt Fast movement of blocks of memory. BOX x1,y1,x2,y2 Draws a rectangle. CIRCLE x,y,r,s,e Draws a circle or arc. CLS Clears the screen. COLOR c Sets the color for drawing. DEFFILL c,a$ Sets user defined color and fill pattern as defined in a$. DEFFILL c,a,b Sets fill color and pattern. DEFLINE style,width,type,start,end Sets line style, line width, type of line, and starting and ending point types. DEFMARK c,t,g Sets color, type and corner points for POLYMARK. DEFTEXT c,s,r,g Defines color, style, rotation and size of text. DRAW [TO] x1,y1 Draws and connects two or more points with straight lines. DRAW x1,y1 [TO] x2,y2 Draws and connects two or more points with straight lines. ELLIPSE x,y,rx,ry Draws an ellipse. FILL x,y Fills an area with a specified pattern. GET x1,y1,x2,y2,a$ Reads a rectangle from the screen and stores it in a string. GRAPHMODE n Sets graphic mode: 1 Replace 2 Transparent 3 XOR 4 Reverse transparent LINE x1,y1,x2,y2 Connects two points with a straight line. PBOX x1,y1,x2,y2 Draws a filled rectangle. PCIRCLE x,y,r,s,e Draws a filled circle or arc. PLOT x,y Draws a single point on the screen. POINT(x,y) Returns the color value of a specified pixel location. POLYFILL n,x(),y() Draws a filled-in shape with n corner points. POLYLINE n,x(),y() Draws a shape with n corner points. POLYMARK n,x(),y() Marks n corner points. PRBOX x1,y1,x2,y2 Draws a filled rectangle with rounded corners. PUT x1,y1,a$ Places a string obtained with GET onto the screen. RBOX x1,y1,x2,y2 Draws a rectangle with rounded corners. SETCOLOR i,n Defines color components. SETCOLOR i,r,g,b Defines red, green and blue color components. SGET a$ Copies screen memory into a 32K string. SPRITE a$,x,y Puts a predefined sprite on the screen at the location specified by x and y. SPUT a$ Copies 32K byte string to screen memory. TEXT x,y,a$ Places text on the screen at the position specified by x and y. VSYNC Wait for vertical blank. MOUSE FUNCTIONS DEFMOUSE a$ Defines a mouse form. DEFMOUSE n Selects a predefined mouse form. HIDEM Hides mouse. MOUSE x,y,k Returns the mouse position (x,y) and status of the mouse buttons (k). MOUSEK Returns status of mouse buttons. 0 None pressed 1 Left button down 2 Right button down 3 Both down MOUSEX Returns horizontal coordinate of the mouse pointer. MOUSEY Returns vertical coordinate of the mouse pointer. SHOWM Shows mouse. SOUND FUNCTIONS SOUND voc,vol,note,oct[,dur] Generates tones. SOUND voc,vol,period[,dur] Generates tones. WAVE voc,env,form,len,dur Defines waveform for sound. TIME FUNCTIONS DATE$ Returns system data as a character string in format mm/dd/yyyy. PAUSE n Suspends program execution for n/50 seconds. SETTIME t$,d$ Sets the time and date. TIME$ Returns the system time as a character string in the format hh:mm:ss. TIMER Returns the time since the system was turned on in 200ths of a second. WINDOWS AND MENUS ALERT icon,text,string,button,button text,x Creates an Alert box Icon Displays 0 Nothing. 1 Exclamation point. 2 Question mark. 3 Stop sign. CLEARW n Clease the contents of the window specified by n. CLOSEW 0 Switches to normal screen display. CLOSEW n Closes the window specified by n. FULLW n Enlarges window n to full screen size. INFOW n,"info" Defines a new information line for the window specified by n. MENU field() Creates menu bar. MENU KILL Deactivates menu bar. MENU n,x Alters menu items. 0 Removes checkmark. 1 Places checkmark. 2 Writes in plain letters, cannot be selected. 3 Writes in normal letters, can be selected. MENU OFF Disables menu titles in "normal" mode. MENU(f) Detects events for ON MENU GOSUB. ON MENU Handles menu selection. ON MENU BUTTON c,m,s GOSUB name Defines procedure for handling mouse button presses. ON MENU GOSUB name Defines precedure which handles menu selection. ON MENU IBOX a,x,y,b,h GOSUB name Defines the procedure for when the mouse moves into a defined rectangular area. ON MENU KEY GOSUB name Defines procedure which handles keyboard input. ON MENU MESSAGE GOSUB name Defines the procedure for handling GEM messages. ON MENU OBOX a,x,y,b,h GOSUB name Defines the procedure for when the mouse moves out of a defined rectangular area. OPENW 0 Opens the whole screen as a window without a menu bar. OPENW n,x,y Opens a specified window at the coordinates x,y. TITLEW n,"title" Assigns a new name to the window specified by n. MACHINE LEVEL COMMANDS BIOS(n,parameter list) Calls TOS BIOS functions. C:var(parameters) Calls a compiled C or machine language subprogram located in memory at the address specified by var. Parameters are transferred as in C. CALL var [(parameters)] Calls a machine language program located in memory at the address sppecified by var. DPEEK(addr) Returns the contents of two bytes of memory. DPOKE addr,n Writes two bytes to addresses in memory. GEMDOS(n,parameter list) Calls TOS GEMDOS functions. GEMSYS Calls the AES function specified by the function number entered in the GCONTRL block. GEMSYS(n) Calls the AES functions specified by n. LPEEK(addr) Returns the contents of four bytes from an address in memory. LPOKE addr,n Writes four bytes to an address in memory. MONITOR Calls a memory resident monitor program or a commands extension. PEEK(addr) Returns the contents of one byte of memory. POKE addr,n Writes one byte to an address in memory. RESERVE n Increases or decreases the amount of memory available to GFA BASIC. SDPOKE addr,n Writes two bytes to an address in memory in the 68000's supervisor mode. SLPOKE addr,n Writes four bytes to an address in memory in the 68000's supervisor mode. SPOKE addr,n Writes one byte to an address in memory in the 68000's supervisor mode. VDISYS Calls VDI function with the function number entered in the CONTRL block. VDISYS(n) Calls VDI function without entering the function number in the CONTRL block. ON BREAK ON BREAK Deactivates ON BREAK GOSUB, or restores break conditions. ON BREAK CONT Deactivates <Control><Alternate><Shift> break key sequence. ON BREAK may be used to reactivate keys. ON BREAK GOSUB proc_name Jumps to a procedure when a break key sequence is encountered. ON expression GOSUB proc_list Permits program redirection to a list of procedures. ERROR HANDLING ERR Returns the error code of any error which may have occurred. ERROR n Simulates the occurrence of an error with the specified error code (n). FATAL Returns the value of 0 or -1 depending on which type of an error was enountered. Generally, -1 is an unrecoverable error. ON ERROR Switches to normal error handling methods if an alternate means was previously defined. ON ERROR GOSUB proc_name Defines an error handling procedure. GFA BASIC ERROR MESSAGES 0 Division by zero. 1 Overflow. 2 Number not integer (-21473648 to 2147483647). 3 Number not byte (0-255). 4 Number not word (0-65535). 5 Square root only for positive numbers. 6 Logarithm only for number greater than zero. 7 Undefined error. 8 Memory full. 9 Function or command not possible. 10 String too long (max. size 32,767 characters). 11 Not GFA BASIC v. 1.0 program. 12 Program too long, memory full, NEW. 13 Not GFA BASIC program file, too short, NEW. 14 Field dimensioned twice. 15 Field not dimensioned. 16 Field index too large. 17 DIM index too large. 18 Wrong number of indexes. 19 Procedure not found. 20 Label not found. 21 On Open only "I"nput, "O"utput, "R"andom, "A"ppend and "U"pdate allowed. 22 File already open. 23 File # wrong. 24 File not opened. 25 Input wrong, not numeric. 26 End of file reached. 27 Too many points for Polyline/Polyfill, max. 128. 28 Field must be one dimensional. 29 Number of points larger than field. 30 Merge not an ASCII file. 31 Merge line too long -- aborted. 32 ==>Syntax error -- program aborted. 33 Label not defined. 34 Insufficient data. 35 Data not numeric. 36 Syntax error in DATA unpaired quotes. 37 Disk full. 38 Command not possible in direct mode. 39 Program error -- GOSUB not possible. 40 CLEAR not possible in FOR - NEXT loops and procedures. 41 CONT not possible. 42 Too few parameters. 43 Expression too complex. 44 Function not defined. 45 Too many parameters. 46 Parameter wrong -- must be numeric. 47 Parameter wrong -- must be string. 48 Open "R" -- record length wrong. 49 Undefined error. 50 Not an "R" file. 51 Only one field per Open "R" allowed. 52 Fields larger than record length. 53 Too many fields (max. 9). 54 GET/PUT fields string length wrong. 55 GET/PUT record number wrong. 56 String has wrong length for SPRITE. 90 Error in LOCAL. 92 Resume (next) not possible FATAL, FOR or LOCAL. 100 Version # of GFA BASIC. TOS AND GFA BASIC COMPILER ERROR MESSAGES -1 General error. -2 Drive not ready -- time exceeded. -3 Undefined error. -4 CRC error -- disk checking sum wrong. -5 Bad request -- invalid command. -6 Seek error -- track not found. -7 Unknown media -- boot sector wrong. -8 Sector not found. -9 No paper. -10 Write fault. -11 Read fault. -12 General error 12. -13 Disk is write protected. -14 Disk has been changed. -15 Unknown device. -16 Bad sector (verify). -17 Insert other disk. -32 Invalid function number. -33 File not found. -34 Path not found. -35 Too many files open. -36 Access not possible. -37 Invalid handle. -39 Memory full. -40 Invalid memory block address. -46 Invalid drive ID. -49 No further files. -64 GEMDOS range error -- seek wrong? -65 GEMDOS internal error. -66 Not binary program file. -67 Memory block error. 68000 EXCEPTION (BOMB) ERROR MESSAGES CODE BOMBS MEANING 102 2 bombs Bus error -- PEEK or POKE possibly wrong. 103 3 bombs Address error. Odd word address. Possibly in DPOKE, DPEEK, LPOKE or LPEEK. 104 4 bombs Illegal instruction; execution of an invalid 68000 assembler command. 105 5 bombs Division by zero in 68000 ML. 106 6 bombs CHK exception. 107 7 bombs TRAPV exception. 108 8 bombs Privilege violation. 109 9 bombs Trace exception. VT52 TERMINAL ESCAPE CODES ESCAPE FUNCTION CHR$(27)+ A Cursor up one line. B Cursor down one line. C Cursor right one char. D Cursor left one char. E Clear screen. H Home cursor. I Cursor up one line with scroll. J Erase to end of page. K Clear to end of line. L Insert line. M Delete line. Y,r,c Position cursor at row, column. b,f Set foreground color. c,b Set background color. d Erase to start of page. e Show cursor f Hide cursor. j Save cursor. k Restore cursor. l Erase line. o Erase to start of line. p Reverse video. q Normal video. v Wrap at end of line. w Discard end of line.