README file for


               Bywater BASIC Interpreter, version 3.00
               ---------------------------------------------

                    Copyright (c) 1993, Ted A. Campbell
                  for bwBASIC version 2.10, 11 October 1993

               Version 2.20 modifications by Jon B. Volkoff,
                             25 November 1995

                  Patch level 1 release by Jon B. Volkoff,
                              15 March 1996

                  Patch level 2 release by Jon B. Volkoff,
                             11 October 1997

               Version 2.30 modifications by Paul Edwards,
                               5 March 2008

               Version 2.40 modifications by Paul Edwards,
                                26 Jan 2009

               Version 2.50 modifications by Paul Edwards,
                                4 June 2009

               Version 2.60 modifications by Paul Edwards,
                              6 November 2012

               Version 2.61 modifications by Paul Edwards,
                              4 August 2014

               Version 3.00 modifications by Howard Wulf, AF5NE
                               12 May 2015





DESCRIPTION:

   The Bywater BASIC Interpreter (bwBASIC) implements a large
   superset of the ANSI Standard for Minimal BASIC (X3.60-1978)
   and a significant subset of the ANSI Standard for Full BASIC
   (X3.113-1987) in C. It also offers shell programming facilities
   as an extension of BASIC. bwBASIC seeks to be as portable
   as possible.

   This version of Bywater BASIC is released under the terms of the 
   GNU General Public License (GPL), which is distributed with this 
   software in the file "COPYING".  The GPL specifies the terms 
   under which users may copy and use the software in this distribution.

   A separate license is available for commercial distribution,
   for information on which you should contact the author.



OBTAINING THE SOURCE CODE:

   The source code for bwBASIC is available from
   http://bwbasic.sourceforge.net



COMMUNICATIONS:

   email:  tcamp@delphi.com  (for Ted Campbell)
           eidetics@cerf.net (for Jon Volkoff)
           fight.subjugation@gmail.com (for Paul Edwards)


A LIST OF BASIC COMMANDS AND FUNCTIONS IMPLEMENTED in bwBASIC:

   Be aware that many of these commands and functions will not be
   available unless you have enabled a particular dialect using
   the OPTION VERSION command. 

     ? expressions...
     ABS( X )
     ACOS( X )
     ANGLE( X, Y )
     ARGC
     ARGT$( X )
     ARGV$( X )
     ARGV( X )
     ASC( A$ )
     ASIN( X )
     ATN( X )
     CALL subroutine-name [parameter [, ...] ]
     CASE ELSE
     CASE IF partial-expression
     CASE IS
     CASE constant
     CCUR( X )
     CDBL( X )
     CEIL( X )
     CHAIN filename$
     CHANGE A$ TO X | CHANGE X TO A$
     CHDIR( A$ )
     CHR$( X )
     CINT( X )
     CLEAR
     CLNG( X )
     CLOAD [file-name$]
     CLOAD* ArrayName
     CLOSE( X )
     CLS
     CMDS
     COLOR( X, Y )
     COMMON variable [, ...]
     CONT
     COS( X )
     COSH( X )
     COT( X )
     CSAVE [file-name$]
     CSAVE* ArrayName
     CSC( X )
     CSNG( X )
     CVC( A$ )
     CVD( A$ )
     CVI( A$ )
     CVL( A$ )
     CVS( A$ )
     DATA constant[, ...]
     DATE
     DATE$
     DEF FN
     DEF FNname(arg...)] = expression
     DEF SUB
     DEFDBL letter[-letter] [, ...]
     DEFINT  letter[-letter] [, ...]
     DEFSNG letter[-letter] [, ...]
     DEFSTR letter[-letter] [, ...]
     DEG( X )
     DELETE line [- line]
     DIM variable( elements [, ...]) [, ...]
     DO
     DO UNTIL expression
     DO WHILE expression
     EDIT
     ELSE
     ELSEIF
     END
     END FUNCTION
     END IF
     END SELECT
     END SUB
     ENVIRON$( A$ )
     ENVIRON( A$ )
     EOF( X )
     EPS( X )
     ERASE variable [, ...]
     ERL
     ERR
     ERR$
     ERROR( X )
     ERROR( X, A$ )
     EXIT
     EXIT DO
     EXIT FOR
     EXIT FUNCTION
     EXIT SUB
     EXIT UNTIL
     EXIT WHILE
     EXP( X )
     FIELD [#] device-number, number AS string-variable$ [, ...]
     FILEATTR( X, Y )
     FILES
     FILES( A$ )
     FIX( X )
     FNCS
     FOR variable = start TO finish [STEP increment]
     FP( X )
     FRE
     FRE( A$ )
     FRE( X )
     FREEFILE
     FUNCTION [ ( parameter [, ...  ] ) ]
     GET( X )
     GET( X, Y )
     GO
     GOSUB line
     GOTO line
     HELP name
     HEX$( X )
     IF expression THEN
     IF expression THEN line1 [ELSE line2]
     INKEY$
     INP( X )
     INPUT [# device-number]|[;]["prompt string";]list of variables
     INPUT$( X )
     INPUT$( X, Y )
     INSTR( A$, B$ )
     INSTR( X, A$, B$ )
     INT( X )
     IP( X )
     KILL( A$ )
     LCASE$( A$ )
     LEFT$( A$, X )
     LEN( A$ )
     [LET] variable = expression
     LINE INPUT [[#] device-number,]["prompt string";] string-variable$
     LIST line1 [- line2]
     LOAD [file-name$]
     LOC( X )
     LOCATE( X, Y )
     LOF( X )
     LOG( X )
     LOG10( X )
     LOG2( X )
     LOOP
     LOOP UNTIL
     LOOP WHILE
     LPOS
     LPRINT [USING format-string$;] expressions...
     LSET string-variable$ = expression
     LTRIM$( A$ )
     LWIDTH( X )
     MAINTAINER
     MAX( X, Y )
     MAXBYT
     MAXCUR
     MAXDBL
     MAXDEV
     MAXINT
     MAXLEN( A$ )
     MAXLNG
     MAXLVL
     MAXNUM
     MAXSNG
     MERGE file-name
     MID$( A$, X )
     MID$( A$, X, Y )
     MID$( variable$, start [, count ] ) = expression
     MIN( X, Y )
     MINBYT
     MINCUR
     MINDBL
     MINDEV
     MININT
     MINLNG
     MINNUM
     MINSNG
     MKC$( X )
     MKD$( X )
     MKDIR( A$ )
     MKI$( X )
     MKL$( X )
     MKS$( X )
     MOD( X, Y )
     NAME old-file-name AS new-file-name
     NAME( A$, B$ )
     NEW
     NEXT [variable]
     NULL( X )
     OCT$( X )
     ON ERROR GOTO errline   |   ON ERROR RESUME NEXT
     ON TIMER count GOSUB line
     ON expression GOTO | GOSUB line [, ...]
     OPEN file-name [FOR INPUT|OUTPUT|APPEND|BINARY|RANDOM] AS [#]device-number [LEN = record-length]
     OPEN( A$, X, B$ )
     OPEN( A$, X, B$, Y )
     OPTION ...
     OPTION ANGLE DEGREES
     OPTION ANGLE RADIANS
     OPTION ARITHMETIC DECIMAL
     OPTION ARITHMETIC FIXED
     OPTION ARITHMETIC NATIVE
     OPTION BASE 0
     OPTION BASE 1
     OPTION BUGS OFF
     OPTION BUGS ON
     OPTION COMPARE BINARY
     OPTION COMPARE TEXT
     OPTION COVERAGE OFF
     OPTION COVERAGE ON
     OPTION INDENT number
     OPTION STRICT OFF
     OPTION STRICT ON
     OPTION TERMINAL ADM-3A
     OPTION TERMINAL ANSI
     OPTION TERMINAL NONE
     OPTION TRACE OFF
     OPTION TRACE ON
     OPTION VERSION [version] 
     ORD( A$ )
     OUT( X, Y )
     PEEK( X )
     PI
     POKE( X, Y )
     POS
     POS( A$, B$ )
     POS( A$, B$, X )
     POS( X )
     PRINT [# device-number,][USING format-string$;] expressions...
     PUT( X )
     PUT( X, Y )
     QUIT
     RAD( X )
     RANDOMIZE
     RANDOMIZE( X )
     READ variable [, ...]
     REM ...
     REMAINDER( X, Y )
     RENUM
     REPEAT$( X, A$ )
     REPEAT$( X, Y )
     RESET
     RESTORE [line]
     RESUME [ 0 | line | NEXT ]
     RETURN
     RIGHT$( A$, X )
     RMDIR( A$ )
     RND
     RND( X )
     ROUND( X, Y )
     RSET string-variable$ = expression
     RTRIM$( A$ )
     RUN [line | file-name$]
     SAVE [file-name$]
     SEC( X )
     SEEK( X )
     SEEK( X, Y )
     SELECT
     SELECT CASE expression
     SGN( X )
     SHELL( A$ )
     SIN( X )
     SINH( X )
     SPACE$( X )
     SPC( X )
     SQR( X )
     STOP
     STR$( X )
     STRING$( X, A$ )
     STRING$( X, Y )
     SUB name [ ( parameter [,...] ) ]
     SWAP variable, variable
     SYSTEM
     TAB( X )
     TAN( X )
     TANH( X )
     TIME
     TIME$
     TIMER
     TIMER ON | STOP | OFF
     TRIM$( A$ )
     TROFF
     TRON
     TRUNCATE( X, Y )
     UCASE$( A$ )
     UEND
     UNTIL expression
     USER LBL
     VAL( A$ )
     VARS
     WAIT( X, Y )
     WAIT( X, Y, Z )
     WEND
     WHILE
     WIDTH( X )
     WIDTH( X, Y )
     WRITE [# device-number,] element [, .... ]




CHANGE HISTORY


CHANGES FROM 2.61 to 3.00

   * Code redesign from Howard Wulf, AF5NE


CHANGES FROM 2.60 to 2.61

   * Bug fix from Matthias Rustler


CHANGES FROM 2.50 to 2.60

   * New maths functions and append mode support from Edmond Orignac
   
   * Bug fixes


CHANGES FROM 2.40 to 2.50

   * Bug fixes
   
   * New compilation procedure for MVS and CMS


CHANGES FROM 2.30 to 2.40

   * Bug fixes from Bill Chatfield
   
   * Updated documentation

   * Added support for compiling on CMS (another IBM mainframe OS)


CHANGES FROM 2.20pl2 to 2.30

   * Minor bug fixes, cosmetic improvements and portability improvements

   * Added support for compiling on MVS (IBM mainframe)


CHANGES FROM 2.20pl1 to 2.20pl2

bwb_cmd.c
   Fixed calling stack level logic in RETURN statement to prevent erroneous
   "RETURN without GOSUB" messages.

bwb_cnd.c
bwb_stc.c

   Changed continuation condition for WHILE, ELSEIF, and LOOP UNTIL
   to be != FALSE, not == TRUE.  More in line with common commercial
   BASIC implementations.

bwb_mth.c
   Fixed initialization in VAL function so that old results are not later
   returned as values.

bwb_var.c
   Added parenthesis level checking to dim_getparams. Using multi-level
   expressions as array subscripts was causing the program to bomb.

bwx_iqc.c
bwx_tty.c
bwb_mes.h
   Added second copyright notice.

bwb_dio.c
bwb_str.c
   Added support for strings longer than 255 characters.

bwb_prn.c
   Disabled tab expansion and print width checks when not printing to a file.

bwb_inp.c
   Fixed LINE INPUT file reads to accommodate strings of length MAXSTRINGSIZE.

bwx_ncu.h
bwx_ncu.c
   New files.  Code for UNIX ncurses interface, compliments of L.C. Benschop,
   Eindhoven, The Netherlands.

Makefile.ncu
   New files.  Sample makefile for ncurses implementation.

bwbasic.h
   Revised defines for MININTSIZE and MAXINTSIZE from 16-bit to 32-bit limits.
   Revised define for MAXSTRINGSIZE from 255 to 5000 characters.
   Changed string length from unsigned char to unsigned int to support strings
   longer than 255 characters.
   Added support for new ncurses package.
   Revised VERSION define to reflect above changes.


CHANGES FROM 2.20 to 2.20pl1

bwb_cnd.c

   Moved init routine for bwb_while so that it would be initialized regardless
   of expression value, not just if TRUE.  This was causing some segmentation
   faults in WHILE-WEND loops.

bwb_elx.c

   Plugged gaping memory leak.  Temp variable space for expression evaluation
   was being allocated but not freed when done (oops!).

bwb_fnc.c

   Added check for NULL return from getenv to prevent segmentation faults.

bwbasic.h
   Revised VERSION define to reflect above changes.



CHANGES FROM 2.10 to 2.20:

   * Plugged numerous memory leaks, resolved memory overruns and allocation
     difficulties.

   * General cleanup and bug fixes, too many to list in detail here.
     The major problem areas addressed were:

      - RUN command with file name argument
      - nested and cascaded FOR-NEXT loops
      - PRINT USING
      - EOF, LOF functions
      - string concatenation
      - operator hierarchy
      - multi-level expression evaluation
      - hex constant interpretation
      - hex and octal constants in INPUT and DATA statements

   * Added a CLOSE all files feature (when no argument supplied).

   * Added a unary minus sign operator.

   * Added a MID$ command to complement the MID$ function.

   * Added a RENUM facility in a standalone program.

   * Added checking in configure for unistd.h (important on Sun systems).