bwBASIC/INFO/Bwbasic-Doc-2.1.txt

BWBASIC(1)                  General Commands Manual                 BWBASIC(1)

NAME
       bwbasic - Bywater BASIC interpreter/shell

                      Bywater BASIC Interpreter/Shell, version 2.10
                      ---------------------------------------------

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

       CONTENTS:

          1. DESCRIPTION
          2. TERMS OF USE
          3. QUICK REFERENCE LIST OF COMMANDS AND FUNCTIONS
          4. GENERAL NOTES ON USAGE
          5. EXPANDED REFERENCE FOR COMMANDS AND FUNCTIONS
          6. PREDEFINED VARIABLES
          7. UNIMPLEMENTED COMMANDS AND FUNCTIONS
             and AGENDA FOR DEVELOPMENT
          8. THE STORY OF BYWATER BASIC
          9. COMMUNICATIONS

          The author wishes to express his thanks to Mr. David MacKenzie,
          who assisted in the development Unix installation and configuration
          for this version.

       1. 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.

          bwBASIC can be configured to emulate features, commands, and
          functions available on different types of BASIC interpreters;
          see the file INSTALL for further installation information.

          The interpreter is fairly slow.  Whenever faced with a choice
          between conceptual clarity and speed, I have consistently chosen
          the former.  The interpreter is the simplest design available,
          and utilizes no system of intermediate code, which would speed
          up considerably its operation.  As it is, each line is interpreted
          afresh as the interpreter comes to it.

          bwBASIC implements one feature not available in previous BASIC
          interpreters: a shell command can be entered interactively at the
          bwBASIC prompt, and the interpreter will execute it under a
          command shell.  For instance, the command "dir *.bas" can be
          entered in bwBASIC (under DOS, or "ls -l *.bas" under UNIX) and
          it will be executed as from the operating system command line.
          Shell commands can also be given on numbered lines in a bwBASIC
          program, so that bwBASIC can be used as a shell programming
          language. bwBASIC's implementation of the RMDIR, CHDIR, MKDIR,
          NAME, KILL, ENVIRON, and ENVIRON$() commands and functions
          offer further shell-processing capabilities.

       2. TERMS OF USE:

          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.

       3. QUICK REFERENCE LIST OF COMMANDS AND FUNCTIONS

          Be aware that many of these commands and functions will not be
          available unless you have set certain flags in the header files
          (see the expanded reference section below for dependencies).

          ABS( number )
          ASC( string$ )
          ATN( number )
          CALL subroutine-name
          CASE ELSE | IF partial-expression | constant
          CHAIN [MERGE] file-name [, line-number] [, ALL]
          CHDIR pathname
          CHR$( number )
          CINT( number )
          CLEAR
          CLOSE [[#]file-number]...
          CLS
          COMMON variable [, variable...]
          COS( number )
          CSNG( number )
          CVD( string$ )
          CVI( string$ )
          CVS( string$ )
          DATA constant[,constant]...
          DATE$
          DEF FNname(arg...)] = expression
          DEFDBL letter[-letter](, letter[-letter])...
          DEFINT letter[-letter](, letter[-letter])...
          DEFSNG letter[-letter](, letter[-letter])...
          DEFSTR letter[-letter](, letter[-letter])...
          DELETE line[-line]
          DIM variable(elements...)[variable(elements...)]...
          DO NUM|UNNUM
          DO [WHILE expression]
          EDIT
          ELSE
          ELSEIF
          END IF | FUNCTION | SELECT | SUB
          ENVIRON variable-string = string
          ENVIRON$( variable-string )
          EOF( device-number )
          ERASE variable[, variable]...
          ERL
          ERR
          ERROR number
          EXP( number )
          FIELD [#] device-number, number AS string-variable [, number AS string-variable...]
          FILES filespec$
          FUNCTION
          FOR counter = start TO finish [STEP increment]
          GET [#] device-number [, record-number]
          GOSUB line | label
          GOTO line | label
          HEX$( number )
          IF expression THEN [statement [ELSE statement]]
          INKEY$
          INPUT [# device-number]|[;]["prompt string";]list of variables
          INSTR( [start-position,] string-searched$, string-pattern$ )
          INT( number )
          KILL file-name
          LEFT$( string$, number-of-spaces )
          LEN( string$ )
          LET variable = expression
          LINE INPUT [[#] device-number,]["prompt string";] string-variable$
          LIST line[-line]
          LOAD file-name
          LOC( device-number )
          LOCATE line, column
          LOF( device-number )
          LOG( number )
          LOOP [UNTIL expression]
          LSET string-variable$ = expression
          MERGE file-name
          MID$( string$, start-position-in-string[, number-of-spaces ] )
          MKD$( number )
          MKDIR pathname
          MKI$( number )
          MKS$( number )
          NAME old-file-name AS new-file-name
          NEW
          NEXT [counter]
          OCT$( number )
          ON variable GOTO|GOSUB line[,line,line,...]
          ON ERROR GOSUB line
          OPEN "O"|"I"|"R", [#]device-number, file-name [,record length]
               file-name FOR INPUT|OUTPUT|APPEND AS [#]device-number [LEN = record-length]
          OPTION BASE number
          POS
          PRINT [# device-number,][USING format-string$;] expressions...
          PUT [#] device-number [, record-number]
          QUIT
          RANDOMIZE number
          READ variable[, variable]...
          REM string
          RESTORE line
          RETURN
          RIGHT$( string$, number-of-spaces )
          RMDIR pathname
          RND( number )
          RSET string-variable$ = expression
          RUN [line][file-name]
          SAVE file-name
          SELECT CASE expression
          SGN( number )
          SIN( number )
          SPACE$( number )
          SPC( number )
          SQR( number )
          STOP
          STR$( number )
          STRING$( number, ascii-value|string$ )
          SUB subroutine-name
          SWAP variable, variable
          SYSTEM
          TAB( number )
          TAN( number )
          TIME$
          TIMER
          TROFF
          TRON
          VAL( string$ )
          WEND
          WHILE expression
          WIDTH [# device-number,] number
          WRITE [# device-number,] element [, element ]....

       4. GENERAL NOTES ON USAGE:

          4.a. Interactive Environment

          An interactive environment is provided if the flag INTERACTIVE
          is defined as TRUE in bwbasic.h, so that a line with a
          line number can be entered at the bwBASIC prompt and it will be
          added to the program in memory.

          Line numbers are not strictly required, but are useful if the
          interactive environment is used for programming.  For longer
          program entry one might prefer to use an ASCII text editor, and
          in this case lines can be entered without numbers. One can use
          DO NUM and DO UNNUM to number or unnumber lines. See also the
          documentation below for the pseudo-command EDIT.

          4.b. Naming Conventions

          Command names and function names are not case sensitive,
          so that "Run" and "RUN" and "run" are equivalent and "abs()"
          and "ABS()" and "Abs()" are equivalent. HOWEVER, variable
          names ARE case sensitive in bwbASIC, so that "d$" and "D$"
          are different variables.  This differs from some BASIC
          implementations where variable names are not case sensitive.

          Variable names can use any alphabetic characters, the period
          and underscore characters and decimal digits (but not in the
          first position). They can be terminated with '#' or '!' to
          allow Microsoft-type names, even though the precision is
          irrelevant to bwBASIC.

          4.c. Numerical Constants

          Numerical constants may begin with a digit 0-9 (decimal), with
          the "&H" or "&h" (hexadecimal) or the "&o" or "&O" (octal).
          Decimal numbers may terminated with 'E', 'e', 'D', or 'd'
          followed by an exponent number to denote exponential notation.
          Decimal constants may also be terminated by the '#' or '!'
          to comply with Microsoft-style precision terminators, although
          the precision specified will be irrelevant to bwBASIC.

          4.d. Command-Line Execution

          A filename can be specified on the command line and will be
          LOADed and RUN immediately, so that the command line

             bwbasic prog.bas

          will load and execute "prog.bas".

          4.e. Program Storage

          All programs are stored as ASCII text files.

          4.f. TRUE and FALSE

          TRUE is defined as -1 and FALSE is defined as 0 in the default
          distribution of bwBASIC. These definitions can be changed by
          those compiling bwBASIC (see file BWBASIC.H).

          4.g. Assignments

          Assignment must be made to variables.  This differs from some
          implementations of BASIC where assignment can be made to a
          function.  Implication: "INSTR( 3, x$, y$ ) = z$" will not
          work under bwBASIC.

          4.h. Operators and Precedence

          bwBASIC recognizes the following operators, with their level
          of precedence given (1 = highest):

             ^                 1       exponentiation
             *                 2       multiplication
             /                 2       division
                              3       integer division
             +                 5       addition
             -                 5       subtraction
             =                 6       equality or assignment
             MOD               4       modulus (remainder) arithmetic
             <>                7       inequality
             <                 8       less than
             >                 9       greater than
             <=                10      less than or equal to
             =<                10      less than or equal to
             >=                11      greater than or equal to
             =>                11      greater than or equal to
             NOT               12      negation
             AND               13      conjunction
             OR                14      disjunction
             XOR               15      exclusive or
             IMP               16      implication
             EQV               17      equivalence

          4.h. Numerical Precision (NOT)

          bwBASIC utilizes numbers with only one level of precision. If
          the flag NUMBER_DOUBLE is defined as TRUE in bwbasic.h, the
          precision implemented will be that of the C "double" data type;
          otherwise (default) the precision will be that of the C "float"
          type.  At a number of points there are commands (or pseudo-
          commands) that seem to recognize Microsoft-style precision
          distinctions, but for the most part these are just work-around
          aliases to allow Microsoft-style programs to be run.

       5. EXPANDED REFERENCE FOR COMMANDS AND FUNCTIONS

          The "Dependencies" listed in the following reference materials
          refers to flags that must be set to TRUE in bwbasic.h for the
          associated command or function to be implemented.  These flags
          are as follows:

          (core)               Commands and Functions in any implementation of
                               bwBASIC; these are the ANSI Minimal BASIC core

          INTERACTIVE          Commands supporting the interactive programming
                               environment

          COMMON_CMDS          Commands beyond ANSI Minimal BASIC which are common
                               to Full ANSI BASIC and Microsoft BASICs

          COMMON_FUNCS         Functions beyond the ANSI Minimal BASIC core, but
                               common to both ANSI Full BASIC and Microsoft-style
                               BASIC varieties

          UNIX_CMDS            Commands which require Unix-style directory and
                               environment routines not specified in C

          STRUCT_CMDS          Commands related to structured programming; all
                               of these are part of the Full ANSI BASIC standard

          ANSI_FUNCS           Functions unique to ANSI Full BASIC

          MS_CMDS              Commands unique to Microsoft BASICs

          MS_FUNCS             Functions unique to Microsoft BASICs

          ------------------------------------------

          Function:     ABS( number )

          Description:  ABS returns the absolute value of the argument 'number'.

          Dependencies: (core)

          ------------------------------------------

          Function:     ASC( string$ )

          Description:  ASC returns the ASCII code for the first letter in
                        the argument string$.

          Dependencies: MS_FUNCS

          ------------------------------------------

          Function:     ATN( number )

          Description:  ATN returns the arctangent value of the argument 'number'
                        in radians.

          Dependencies: (core)

          ------------------------------------------

          Command:      CALL subroutine-name

          Description:  CALL calls a named subroutine (see SUB and END SUB).

          Dependencies: STRUCT_CMDS

          ------------------------------------------

          Command:      CASE ELSE | IF partial-expression | constant

          Description:  CASE introduces an element of a SELECT CASE statement
                        (see SELECT CASE). CASE IF introduces a conditional
                        SELECT CASE element, and CASE ELSE introduces a
                        default SELECT CASE element.

          Dependencies: STRUCT_CMDS

          ------------------------------------------

          Command:      CHAIN [MERGE] file-name [, line-number] [, ALL]

          Description:  CHAIN passes control to another BASIC program.
                        Variables declared COMMON (q.v.) will be passed
                        to the new program.

          Dependencies: COMMON_CMDS

          ------------------------------------------

          Command:      CHDIR pathname$

          Description:  CHDIR changes the current directory to that indicated
                        by the argument pathname$.

          Dependencies: UNIX_CMDS

          ------------------------------------------

          Function:     CHR$( number )

          Description:  CHR$ returns a one-character string with the character
                        corresponding to the ASCII code indicated by argument
                        'number'.

          Dependencies: COMMON_FUNCS

          ------------------------------------------

          Function:     CINT( number )

          Description:  CINT returns the truncated integer for the argument
                        'number'.

          Dependencies: MS_FUNCS

          ------------------------------------------

          Command:      CLEAR

          Description:  CLEAR sets all numerical variables to 0, and all
                        string variables to null.

          Dependencies: COMMON_CMDS

          ------------------------------------------

          Command:      CLOSE [[#]file-number]...

          Description:  CLOSE closes the file indicated by file-number
                        (see OPEN).

          Dependencies: COMMON_CMDS

          ------------------------------------------

          Command:      CLS

          Description:  CLS clears the display screen (IBM and compatibles
                        only as of version 2.10).

          Dependencies: IMP_IQC and IMP_CMDLOC

          ------------------------------------------

          Command:      CMDS

          Description:  CMDS is a debugging command that prints a list
                        of all implemented bwBASIC commands.

          Dependencies: DEBUG

          ------------------------------------------

          Command:      COMMON variable [, variable...]

          Description:  COMMON designates variables to be passed to a CHAINed
                        program (see CHAIN).

          Dependencies: COMMON_CMDS

          ------------------------------------------

          Function:     COS( number )

          Description:  COS returns the cosine of the argument 'number'
                        in radians.

          Dependencies: (core)

          ------------------------------------------

          Function:     CSNG( number )

          Description:  CSNG is a pseudo-function that has no effect under
                        bwBASIC.  It replicates a Microsoft-type command
                        that would convert the 'number' to single-precision.

          Dependencies: MS_FUNCS

          ------------------------------------------

          Function:     CVD( string$ )

          Description:  CVD converts the argument string$ into a bwBASIC
                        number (precision is irrelevant in bwBASIC since
                        bwBASIC numbers have only one precision).

          Implementation-Specific Notes:

          CVD(), CVI(), CVS(), MKI$(), MKD$(), MKS$(): These functions
          are implemented, but are dependent on a) the sizes for integer,
          float, and double values on particular systems, and b) how
          particular versions of C store these numerical values. The
          implication is that data files created using these functions
          on a DOS-based microcomputer may not be translated correctly
          by bwBASIC running on a Unix-based computer.  Similarly, data
          files created by bwBASIC compiled by one version of C may not be
          readable by bwBASIC compiled by another version of C (even under
          the same operating system). So be careful with these.

          Dependencies: MS_FUNCS

          ------------------------------------------

          Function:     CVI( string$ )

          Description:  CVI converts the argument string$ into a bwBASIC
                        number (precision is irrelevant in bwBASIC since
                        bwBASIC numbers have only one precision; see also
                        the note on CVD).

          Dependencies: MS_FUNCS

          ------------------------------------------

          Function:     CVS( string$ )

          Description:  CVI converts the argument string$ into a bwBASIC
                        number (precision is irrelevant in bwBASIC since
                        bwBASIC numbers have only one precision; see also
                        the note on CVD).

          Dependencies: MS_FUNCS

          ------------------------------------------

          Command:      DATA constant[,constant]...

          Description:  DATA stores numerical and string constants to be
                        accessed by READ (q.v.).

          Dependencies: (core)

          ------------------------------------------

          Function:     DATE$

          Description:  DATE$ returns the current date based on the computer's
                        internal clock as a string in the form "YYYY-MM-DD".
                        As implemented under bwBASIC, DATE$ cannot be used for
                        assignment (i.e., to set the system date).

          Note:         bwBASIC presently (v2.10) does not allow assignment
                        to a function.

          Dependencies: COMMON_FUNCS

          ------------------------------------------

          Command:      DEF FNname(arg...)] = expression

          Description:  DEF defines a user-written function.  This function
                        corresponds to Microsoft-type implementation, although
                        in bwBASIC DEF is a working equivalent of FUNCTION.

          Dependencies: (core)

          ------------------------------------------

          Command:      DEFDBL letter[-letter](, letter[-letter])...

          Description:  DEFDBL declares variables with single-letter names
                        as numerical variables (precision is irrelevant in
                        bwBASIC).

          Dependencies: MS_CMDS

          ------------------------------------------

          Command:      DEFINT letter[-letter](, letter[-letter])...

          Description:  DEFINT declares variables with single-letter names
                        as numerical variables (precision is irrelevant in
                        bwBASIC).

          Dependencies: MS_CMDS

          ------------------------------------------

          Command:      DEFSNG letter[-letter](, letter[-letter])...

          Description:  DEFSNG declares variables with single-letter names
                        as numerical variables (precision is irrelevant in
                        bwBASIC).

          Dependencies: MS_CMDS

          ------------------------------------------

          Command:      DEFSTR letter[-letter](, letter[-letter])...

          Description:  DEFSTR declares variables with single-letter names
                        as string variables.

          Dependencies: MS_CMDS

          ------------------------------------------

          Command:      DELETE line[-line]

          Description:  DELETE deletes program lines indicated by the
                        argument(s). If you want to use DELETE for non-
                        numbered programs, first use DO NUM, then DELETE,
                        then DO UNNUM.

          Dependencies: INTERACTIVE

          ------------------------------------------

          Command:      DIM variable(elements...)[variable(elements...)]...

          Description:  DIM specifies variables that have more than one
                        element in a single dimension, i.e., arrayed
                        variables.

          Note:         As implemented under bwBASIC, DIM accepts only
                        parentheses as delimiters for variable fields.
                        (Some BASICs allow the use of square brackets.)

          Dependencies: (core)

          ------------------------------------------

          Command:      DO NUM|UNNUM

          Description:  DO NUM numbers all lines in a program.  The first
                        line is given the number 10, and subsequent lines
                        are numbered consecutively in multiples of 10. DO
                        UNNUM removes all line numbers from a program.
                        NOTE that these functions do nothing to line
                        numbers, e.g., following a GOSUB or GOTO statement;
                        these commands cannot be used as a replacement for
                        RENUM (available in some systems, but not bwBASIC).
                        With these commands, however, one can develop
                        unnumbered programs by entering new lines with numbers,
                        then running DO UNNUM to remove the line numbers.
                        Together with LOAD and SAVE (q.v.) one can use
                        bwBASIC as a primitive text editor.

          Dependencies: INTERACTIVE

          ------------------------------------------

          Command:      DO [WHILE expression]

          Description:  DO implements a number of forms of program loops.
                        DO...LOOP simply loops; the only way out is by
                        EXIT; DO WHILE...LOOP loops while "expression" is
                        true (this is equivalent to the older WHILE-WEND
                        loop, also implemented in bwBASIC); DO...LOOP UNTIL
                        loops until the expression following UNTIL is true.

          Dependencies: STRUCT_CMDS

          ------------------------------------------

          Command:      EDIT

          Description:  EDIT is a pseudo-command which calls the text editor
                        specified in the variable BWB.EDITOR$ to edit the
                        program in memory.  After the call to the text editor,
                        the (edited) program is reloaded into memory.  The user
                        normally must specific a valid path and filename in
                        BWB.EDITOR$ before this command will be useful.

          Dependencies: COMMON_CMDS

          ------------------------------------------

          Command:      ELSE

          Description:  ELSE introduces a default condition in a multi-line IF
                        statement.

          Dependencies: STRUCT_CMDS

          ------------------------------------------

          Command:      ELSEIF

          Description:  ELSEIF introduces a secondary condition in a multi-
                        line IF statement.

          Dependencies: STRUCT_CMDS

          ------------------------------------------

          Command:      END IF | FUNCTION | SELECT | SUB

          Description:  END IF ends a multi-line IF statement. END FUNCTION
                        ends a multi-line function definition. END SELECT
                        ends a SELECT CASE statement.  END SUB ends a multi-
                        line subroutine definition.

          Dependencies: STRUCT_CMDS

          ------------------------------------------

          Command:      ENVIRON variable-string$ = string$

          Description:  ENVIRON sets the environment variable identified by
                        variable-string$ to string$.

                        It might be noted that this differs from the implementation
                        of ENVIRON in some versions of BASIC, but bwBASIC's ENVIRON
                        allows BASIC variables to be used on either side of the equals
                        sign.  Note that the function ENVIRON$() is different from the
                        command, and be aware of the fact that in some operating systems
                        an environment variable set within a program will not be passed
                        to its parent shell.

          Dependencies: UNIX_CMDS

          ------------------------------------------

          Function:     ENVIRON$( variable-string$ )

          Description:  ENVIRON$ returns the environment variable associated with
                        the name variable-string$.

          Dependencies: MS_FUNCS

          ------------------------------------------

          Function:     EOF( device-number )

          Description:  EOF returns TRUE (-1) if the device associated with
                        device-number is at the end-of-file, otherwise it
                        returns FALSE (0).

          Dependencies: MS_FUNCS

          ------------------------------------------

          Command:      ERASE variable[, variable]...

          Description:  ERASE eliminates arrayed variables from a program.

          Dependencies: COMMON_CMDS

          ------------------------------------------

          Function:     ERL

          Description:  ERL returns the line number of the most recent error.

          Dependencies: MS_FUNCS

          ------------------------------------------

          Function:     ERR

          Description:  ERR returns the error number of the most recent error.

                        Note that if PROG_ERRORS has been defined when bwBASIC is
                        compiled, the ERR variable will not be set correctly upon
                        errors.  It only works when standard error messages are used.

          Dependencies: MS_FUNCS

          ------------------------------------------

          Command:      ERROR number

          Description:  ERROR simulates an error, i.e., displays the message
                        appropriate for that error. This command is helpful
                        in writing ON ERROR GOSUB routines that can identify
                        a few errors for special treatment and then ERROR ERR
                        (i.e., default handling) for all others.

          Dependencies: COMMON_CMDS

          ------------------------------------------

          Command:      EXIT [FOR]

          Description:  EXIT by itself exits from a DO...LOOP loop;
                        EXIT FOR exits from a FOR...NEXT loop.

          Dependencies: STRUCT_CMDS

          ------------------------------------------

          Function:     EXP( number )

          Description:  EXP returns the exponential value of 'number'.

          Dependencies: (core)

          ------------------------------------------

          Command:      FIELD [#] device-number, number AS string-variable$ [, number AS string-variable$...]

          Description:  FIELD allocates space in a random file buffer for device
                        indicated by device-number, allocating 'number' bytes
                        and assigning the bytes at this position to the variable
                        string-variable$.

          Dependencies: COMMON_CMDS

          ------------------------------------------

          Command:      FILES filespec$

          Description:  FILES is a pseudocommand that invokes the directory program
                        specified in the variable BWB.FILES$ with the argument
                        filespec$.  Normally, the user must set this variable
                        before FILES can be used.  E.g., for PC-type computers,

                           BWB.FILES$ = "DIR"

                        will work, for Unix machines,

                           BWB.FILES$ = "ls -l"

                        etc.

          Dependencies: COMMON_CMDS

          ------------------------------------------

          Command:      FNCS

          Description:  CMDS is a debugging command that prints a list
                        of all pre-defined bwBASIC functions.

          Dependencies: DEBUG

          ------------------------------------------

          Command:      FUNCTION

          Description:  FUNCTION introduces a function definition, normally
                        ending with END FUNCTION.  In bwBASIC, FUNCTION and
                        DEF are working equivalents, so either can be used
                        with single-line function definitions or with multi-
                        line definitions terminated by END FUNCTION.

          Dependencies: STRUCT_CMDS

          ------------------------------------------

          Command:      FOR counter = start TO finish [STEP increment]

          Description:  FOR initiates a FOR-NEXT loop with the variable
                        'counter' initially set to 'start' and incrementing
                        in 'increment' steps (default is 1) until 'counter'
                        equals 'finish'.

          Dependencies: (core)

          ------------------------------------------

          Command:      GET [#] device-number [, record-number]

          Description:  GET reads the next record from a random-access file
                        or device into the buffer associated with that file.
                        If record-number is specified, the GET command reads the
                        specified record.

          Dependencies: COMMON_CMDS

          ------------------------------------------

          Command:      GOSUB line | label

          Description:  GOSUB initiates a subroutine call to the line (or label)
                        specified.  The subroutine must end with RETURN.

          Dependencies: (core), but STRUCT_CMDS for labels

          ------------------------------------------

          Command:      GOTO line | label

          Description:  GOTO branches program execution to the specified line
                        (or label).

          Dependencies: (core), but STRUCT_CMDS for labels

          ------------------------------------------

          Function:     HEX$( number )

          Description:  HEX$ returns a string giving the hexadecimal (base 16)
                        value for the 'number'.

          Dependencies: MS_FUNCS

          ------------------------------------------

          Command:      IF expression THEN [statement [ELSE statement]]

          Description:  IF evaluates 'expression' and performs the THEN
                        statement if it is true or (optionally) the
                        ELSE statement if it is FALSE.  If STRUCT_CMDS
                        is set to TRUE, bwBASIC allows multi-line IF
                        statements with ELSE and ELSEIF cases, ending
                        with END IF.

          Dependencies: (core), STRUCT_CMDS for multi-line IF statements

          ------------------------------------------

          Function:     INKEY$

          Description:  INKEY$ reads the status of the keyboard, and a single
                        keypress, if available. If a keypress is not available,
                        then INKEY$ immediately returns a null string ("").
                        Currently (v2.10) implemented in bwx_iqc.c only.

          Dependencies: IMP_IQC and IMP_CMDLOC

          ------------------------------------------

          Command:      INPUT [# device-number]|[;]["prompt string";]list of variables

          Description:  INPUT allows input from the terminal or a device
                        specified by device-number.  If terminal, the "prompt
                        string" is output, and input is assigned to the
                        appropriate variables specified.

                        bwBASIC does not support the optional feature of INPUT
                        that suppresses the carriage-return and line-feed at the end
                        of the input.  This is because C alone does not provide for any
                        means of input other than CR-LF-terminated strings.

          Dependencies: (core)

          ------------------------------------------

          Function:     INSTR( [start-position,] string-searched$, string-pattern$ )

          Description:  INSTR returns the position at which string-pattern$
                        occurs in string-searched$, beginning at start-position.
                        As implemented in bwBASIC, INSTR cannot be used for
                        assignments.

          Note:         bwBASIC presently (v2.10) does not allow assignment
                        to a function.

          Dependencies: MS_FUNCS

          ------------------------------------------

          Function:     INT( number )

          Description:  INT returns the largest integer less than or equal to
                        the argument 'number'. NOTE that this is not a "truncated"
                        integer function, for which see CINT.

          Dependencies: (core)

          ------------------------------------------

          Command:      KILL file-name$

          Description:  KILL deletes the file specified by file-name$.

          Dependencies: UNIX_CMDS

          ------------------------------------------

          Function:     LEFT$( string$, number-of-spaces )

          Description:  LEFT$ returns a substring a string$ with number-of-spaces
                        from the left (beginning) of the string). As implemented
                        under bwBASIC, it cannot be used for assignment.

          Dependencies: MS_FUNCS

          ------------------------------------------

          Function:     LEN( string$ )

          Description:  LEN returns the length in bytes of string$.

          Dependencies: COMMON_FUNCS

          ------------------------------------------

          Command:      LET variable = expression

          Description:  LET assigns the value of 'expression' to the variable.
                        As currently implemented, bwBASIC supports implied LET
                        statements (e.g., "X = 4.5678" at the beginning of
                        a line or line segment, but does not support assignment
                        to multiple variables (e.g., "x, y, z = 3.141596").

          Dependencies: (core)

          ------------------------------------------

          Command:      LINE INPUT [[#] device-number,]["prompt string";] string-variable$

          Description:  LINE INPUT reads entire line from the keyboard or a file
                        or device into string-variable$.  If input is from the
                        keyboard (stdin), then "prompt string" will be printed
                        first.  Unlike INPUT, LINE INPUT reads a whole line,
                        not stopping for comma-delimited data items.

          Dependencies: COMMON_CMDS

          ------------------------------------------

          Command:      LIST line[-line]

          Description:  LIST lists program lines as specified in its argument.

          Dependencies: INTERACTIVE

          ------------------------------------------

          Command:      LOAD file-name

          Description:  LOAD loads an ASCII BASIC program into memory.

          Dependencies: INTERACTIVE

          ------------------------------------------

          Function:     LOC( device-number )

          Description:  LOC returns the next record that GET or PUT statements
                        will use.

          Dependencies: MS_FUNCS

          ------------------------------------------

          Command:      LOCATE line, column

          Description:  LOCATE addresses trhe curor to a specified line and
                        column. Currently (v2.10) implemented in bwx_iqc.c only.

          Dependencies: IMP_IQC and IMP_CMDLOC

          ------------------------------------------

          Function:     LOF( device-number )

          Description:  LOF returns the length of a file (specified by device-number)
                        in bytes.

          Dependencies: MS_FUNCS

          ------------------------------------------

          Function:     LOG( number )

          Description:  LOG returns the natural logarithm of the argument 'number'.

          Dependencies: (core)

          ------------------------------------------

          Command:      LOOP [UNTIL expression]

          Description:  LOOP terminates a program loop:  see DO.

          Dependencies: STRUCT_CMDS

          ------------------------------------------

          Command:      LSET string-variable$ = expression

          Description:  LSET transfers data from 'expression' to the left-hand
                        side of a string variable or random access buffer field.

          Dependencies: COMMON_CMDS

          ------------------------------------------

          Command:      MERGE file-name

          Description:  MERGE adds program lines from 'file-name' to the program
                        in memory.  Unlike LOAD, it does not clear the program
                        currently in memory.

          Dependencies: COMMON_CMDS

          ------------------------------------------

          Function:     MID$( string$, start-position-in-string[, number-of-spaces ] )

          Description:  MID$ returns a substring of string$ beginning at
                        start-position-in-string and continuing for
                        number-of-spaces bytes.

          Dependencies: MS_FUNCS

          ------------------------------------------

          Command:      MKDIR pathname$

          Description:  MKDIR creates a new directory path as specified by
                        pathname$.

          Dependencies: UNIX_CMDS

          ------------------------------------------

          Function:     MKD$( number )

          Description:  MKD$, MKI$, and MKS$ are all equivalent in bwBASIC.
                        They convert the numerical value 'number' into a string
                        which can be stored in a more compressed form in a file
                        (especially for random file access).  Since bwBASIC does
                        not recognize differences in precision, these commands
                        are effectively equivalent.

          Dependencies: MS_FUNCS

          ------------------------------------------

          Function:     MKI$( number )

          Description:  Equivalent to MKD$ (q.v.)

          Dependencies: MS_FUNCS

          ------------------------------------------

          Function:     MKS$( number )

          Description:  Equivalent to MKD$ (q.v.).

          Dependencies: MS_FUNCS

          ------------------------------------------

          Command:      NAME old-file-name AS new-file-name

          Description:  NAME renames an existing file (old-file-name) as
                        new-file-name.

          Dependencies: UNIX_CMDS

          ------------------------------------------

          Command:      NEW

          Description:  NEW deletes the program in memory and clears all
                        variables.

          Dependencies: INTERACTIVE

          ------------------------------------------

          Command:      NEXT [counter-variable]

          Description:  NEXT comes at the end of a FOR-NEXT loop; see FOR.

          Dependencies: (core)

          ------------------------------------------

          Function:     OCT$( number )

          Description:  OCT$ returns a string giving the octal (base 8)
                        representation of 'number'.

          Dependencies: MS_FUNCS

          ------------------------------------------

          Command:      ON variable GOTO|GOSUB line[,line,line,...]

          Description:  ON either branches (GOTO) or calls a subroutine
                        (GOSUB) based on the rounded value of variable;
                        if it is 1, the first line is called, if 2, the second
                        line is called, etc.

          Dependencies: (core)

          ------------------------------------------

          Command:      ON ERROR GOSUB line|label

          Description:  ON ERROR sets up an error handling subroutine. See
                        also ERROR.

          Dependencies: COMMON_CMDS, STRUCT_CMDS for labels

          ------------------------------------------

          Command:      OPEN "O"|"I"|"R", [#]device-number, file-name [,record length]
                             file-name FOR INPUT|OUTPUT|APPEND AS [#]device-number [LEN = record-length]

          Description:  OPEN allocates random access memory for access to a disk
                        file or other device.  Note that two quite different forms
                        of the OPEN statement are supported. In the first form,
                        "O" (note that these letters must be encased in quotation
                        marks) denotes sequential output, "I" denotes sequential
                        input, and "R" denotes random-access input and output.
                        Once OPEN, any number of operations can be performed
                        on a device (see WRITE #, INPUT #, PRINT #, etc.).

          Dependencies: COMMON_CMDS

          ------------------------------------------

          Command:      OPTION BASE number

          Description:  OPTION BASE sets the lowest value for array subscripts,
                        either 0 or 1.

          Dependencies: (core)

          ------------------------------------------

          Function:     POS

          Description:  POS returns the current cursor position in the line.

          Dependencies: COMMON_FUNCS

          ------------------------------------------

          Command:      PRINT [# device-number,][USING format-string$;] expressions...

          Description:  PRINT outputs text to the screen or to a file or device
                        specified by device-number. In the current implementation
                        of bwBASIC, expressions to be printed must be separated by
                        the comma (tabbed output), the semicolon (immediate
                        sequential output) or the plus sign (immediate sequential
                        output by string concatenation).  Expressions separated
                        by blanks or tabs are not supported. If USING is specified,
                        a number of formatting marks may appear in the format
                        string:

                           !   prints the first character of a string

                           \  prints 2+x characters of a string, where x =
                               the number of spaces between the backslashes

                           &   variable-length string field

                           #   represents a single digit in output format for
                               a number

                           .   decimal point in a number

                           +   sign of a number (will output + or -)

                           -   trailing minus after a number

                           **  fill leading spaces with asterisks

                           $$  output dollar sign in front of a number

                           ^^  output number in exponential format

                           _   output next character literally

                        As currently implemented, the exponential format
                        will be that used by the C compiler.

          Dependencies: (core), COMMON_FUNCS for USING

          ------------------------------------------

          Command:      PUT [#] device-number [, record-number]

          Description:  PUT outputs the next available record or the record
                        specified by record-number to the file or device
                        denoted by device-number.

          Dependencies: COMMON_CMDS

          ------------------------------------------

          Command:      QUIT

          Description:  QUIT is a synonym for SYSTEM; with INTERACTIVE
                        environment, it exits the program to the
                        operating system (or the calling program).

          Dependencies: INTERACTIVE

          ------------------------------------------

          Command:      RANDOMIZE number

          Description:  RANDOMIZE seeds the random number generator (see RND).
                        Under bwBASIC, the TIMER function (q.v.) can be used
                        to supply a 'number' seed for the random number
                        generator.

          Dependencies: (core)

          ------------------------------------------

          Command:      READ variable[, variable]...

          Description:  READ reads values from DATA statements and assigns these
                        values to the named variables.  Variable types in a READ
                        statement must match the data types in DATA statements
                        as they are occurred.  See also DATA and RESTORE.

          Dependencies: (core)

          ------------------------------------------

          Command:      REM string

          Description:  REM allows remarks to be included in a program. As
                        currently implemented, the entire line following
                        REM is ignored by the interpreter (thus, even if
                        MULTISEG_LINES is set, a REM line will not be able
                        to find a segment delimiter (":") followed by another
                        line segment with command.  bwBASIC does not currently
                        implement the Microsoft-style use of the single quotation
                        mark to denote remarks.

          Dependencies: (core)

          ------------------------------------------

          Command:      RESTORE line

          Description:  RESTORE resets the line and position counters for DATA
                        and READ statements to the top of the program file or
                        to the beginning of the specified line.  (Currently this
                        must be a line number.)

          Dependencies: (core)

          ------------------------------------------

          Command:      RETURN

          Description:  RETURN concludes a subroutine called by GOSUB.

          Dependencies: (core)

          ------------------------------------------

          Function:     RIGHT$( string$, number-of-spaces )

          Description:  RIGHT$ returns a substring a string$ with number-of-spaces
                        from the right (end) of the string). As implemented
                        under bwBASIC, it cannot be used for assignment.

          Dependencies: MS_FUNCS

          ------------------------------------------

          Command:      RMDIR pathname

          Description:  RMDIR deletes the directory path indicated by pathname.

          Dependencies: UNIX_CMDS

          ------------------------------------------

          Function:     RND( number )

          Description:  RND returns a pseudo-random number.  The 'number' value
                        is ignored by bwBASIC if supplied. The RANDOMIZE
                        command (q.v.) reseeds the random-number generator.

          Dependencies: (core)

          ------------------------------------------

          Command:      RSET string-variable$ = expression

          Description:  RSET transfers data from 'expression' to the right-hand
                        side of a string variable or random access buffer field.

          Dependencies: COMMON_CMDS

          ------------------------------------------

          Command:      RUN [line][file-name$]

          Description:  RUN executes the program in memory.  If a file-name$ is
                        supplied, then the specified file is loaded into memory
                        and executed.  If a line number is supplied, then execution
                        begins at that line.

          Dependencies: INTERACTIVE

          ------------------------------------------

          Command:      SAVE file-name$

          Description:  SAVE saves the program in memory to file-name$. bwBASIC
                        only saves files in ASCII format.

          Dependencies: INTERACTIVE

          ------------------------------------------

          Command:      SELECT CASE expression

          Description:  SELECT CASE introduces a multi-line conditional selection
                        statement.  The expression given as the argument to SELECT
                        CASE will be evaluated by CASE statements following.  The
                        SELECT CASE statement concludes with an END SELECT
                        statement.

                        As currently implemented, CASE statements may be followed
                        by string values, but in this case only simple comparisons
                        (equals, not equals) can be performed.

          Dependencies: STRUCT_CMDS

          ------------------------------------------

          Function:     SGN( number )

          Description:  SGN returns the sign of the argument 'number', +1
                        for positive numbers, 0 for 0, and -1 for negative numbers.

          Dependencies: (core)

          ------------------------------------------

          Function:     SIN( number )

          Description:  SIN returns the sine of the argument 'number'
                        in radians.

          Dependencies: (core)

          ------------------------------------------

          Function:     SPACE$( number )

          Description:  SPACE$ returns a string of blank spaces 'number'
                        bytes long.

          Dependencies: MS_FUNCS

          ------------------------------------------

          Function:     SPC( number )

          Description:  SPC returns a string of blank spaces 'number'
                        bytes long.

          Dependencies: MS_FUNCS

          ------------------------------------------

          Function:     SQR( number )

          Description:  SQR returns the square root of the argument 'number'.

          Dependencies: (core)

          ------------------------------------------

          Command:      STOP

          Description:  STOP interrupts program execution. As implemented under
                        bwBASIC, STOP issues a SIGINT signal.

          Dependencies: (core)

          ------------------------------------------

          Function:     STR$( number )

          Description:  STR$ returns a string giving the decimal (base 10)
                        representation of the argument 'number'.

          Dependencies: COMMON_FUNCS

          ------------------------------------------

          Function:     STRING$( number, ascii-value|string$ )

          Description:  STRING$ returns a string 'number' bytes long consisting
                        of either the first character of string$ or the character
                        answering to the ASCII value ascii-value.

          Dependencies: MS_FUNCS

          ------------------------------------------

          Command:      SUB subroutine-name

          Description:  SUB introduces a named, multi-line subroutine. The
                        subroutine is called by a CALL statement, and concludes
                        with an END SUB statement.

          Dependencies: STRUCT_CMDS

          ------------------------------------------

          Command:      SWAP variable, variable

          Description:  SWAP swaps the values of two variables. The two variables
                        must be of the same type (either numerical or string).

          Dependencies: COMMON_CMDS

          ------------------------------------------

          Command:      SYSTEM

          Description:  SYSTEM exits from bwBASIC to the calling program or
                        (more usually) the operating system.

          Dependencies: INTERACTIVE

          ------------------------------------------

          Function:     TAB( number )

          Description:  TAB outputs spaces until the column indicated by
                        'number' has been reached.

          Dependencies: (core)

          ------------------------------------------

          Function:     TAN( number )

          Description:  TAN returns the tangent of the argument 'number'
                        in radians.

          Dependencies: (core)

          ------------------------------------------

          Function:     TIME$

          Description:  TIME$ returns the current time based on the computer's
                        internal clock as a string in the form "HH-MM-SS".
                        As implemented under bwBASIC, TIME$ cannot be used for
                        assignment (i.e., to set the system time).

          Note:         bwBASIC presently (v2.10) does not allow assignment
                        to a function.

          Dependencies: COMMON_FUNCS

          ------------------------------------------

          Function:     TIMER

          Description:  TIMER returns the time in the system clock in seconds
                        elapsed since midnight.

          Dependencies: MS_FUNCS

          ------------------------------------------

          Command:      TROFF

          Description:  TROFF turns of the trace facility; see TRON.

          Dependencies: COMMON_CMDS

          ------------------------------------------

          Command:      TRON

          Description:  TRON turns on the trace facility. This facility will print
                        each line number in square brackets as the program is
                        executed.  This is useful in debugging programs with
                        line numbers.  To debug an unnumbered program with
                        TRON, call DO NUM first, but remember to call DO UNNUM
                        before you save the program later.

          Dependencies: COMMON_CMDS

          ------------------------------------------

          Function:     VAL( string$ )

          Description:  VAL returns the numerical value of the string$.

          Dependencies: COMMON_FUNCS

          ------------------------------------------

          Command:      VARS

          Description:  VARS is a debugging command which prints a list of
                        all variables defined which have global scope.

          Dependencies: DEBUG

          ------------------------------------------

          Command:      WEND

          Description:  WEND concludes a WHILE-WEND loop; see WHILE.

          Dependencies: COMMON_CMDS

          ------------------------------------------

          Command:      WHILE expression

          Description:  WHILE initiates a WHILE-WEND loop.  The loop ends with
                        WEND, and execution reiterates through the loop as
                        long as the 'expression' is TRUE (-1).

          Dependencies: COMMON_CMDS

          ------------------------------------------

          Command:      WIDTH [# device-number,] number

          Description:  WIDTH sets screen or device output to 'number'
                        columns.  device-number specifies the device
                        or file for output.

          Dependencies: COMMON_CMDS

          ------------------------------------------

          Command:      WRITE [# device-number,] element [, element ]....

          Description:  WRITE outputs variables to the screen or to a file
                        or device specified by device-number.  Commas
                        are inserted between expressions output, and strings
                        are enclosed in quotation marks.

          Dependencies: COMMON_CMDS

          ------------------------------------------

       6. PREDEFINED VARIABLES

          BWB.EDITOR$
          BWB.FILES$
          BWB.PROMPT$
          BWB.IMPLEMENTATION$

          The commands EDIT and FILES are pseudo-commands that launch
          shell programs named in the variables BWB.EDITOR$ and BWB.FILES$,
          respectively.  The default values for these variables can
          be changed in bwbasic.h (DEF_EDITOR and DEF_FILES), or they
          can be changed on the fly by the user.  An idea might be to
          initialize these variables in "profile.bas" for specific
          implementations; for instance, BWB.FILES$ might be defined as
          "ls -l" on Unix systems or "dir" on DOS systems.

          The preset variable BWB.PROMPT$ can be used to set the prompt
          string for bwBASIC.  Again, it is suggested that a user-
          selected prompt can be set up in a "profile.bas" to be
          initialized each time bwBASIC starts.  Note that special
          characters can be added to the prompt string, e.g.,

             BWB.PROMPT$ = "Ok"+CHR$(10)

          will give an "Ok" prompt followed by a linefeed.

          The preset variable BWB.IMPLEMENTATION$ will return "TTY" for
          the bwx_tty implementation and will return "IQC" for the
          IBM PC or Compatibles with QuickC (bwx_iqc) implementation.
          This may be useful in determining which commands and functions
          (specifically CLS, LOCATE, and INKEY$) may be available.

       7. UNIMPLEMENTED COMMANDS AND FUNCTIONS, and AGENDA FOR DEVELOPMENT

          There are some items not implemented that have been so long
          a part of standard BASICs that their absence will seem surprising.
          In each case, though, their implementation would require opera-
          ting-system-specific functions or terminal-specific functions
          that cannot be universally provided. Some specific examples:

          CLOAD        Relies on CP/M or MSDOS conventions for binary
                       executable files.

          CONT         See RESUME below (programmer ignorance?).

          DEF USR      Relies on CP/M or MSDOS conventions for binary
                       executable files.

          FRE()        The ability to report the amount of free memory
                       remaining is system-specific due to varying patterns
                       of memory allocation and access; consequently this
                       ability is not present in ANSI or earlier versions
                       of C and this function is not available in bwBASIC.

          INPUT$()     C by itself is not able to read unechoed keyboard
                       input, and can read keyboard input only after a
                       Carriage-Return has been entered.

          INP          Calls to hardware ports, like machine-language
                       routines, are highly system-specific and cannot
                       be implemented in C alone.

          LLIST        See LPRINT below.

          LPOS         See LPRINT below.

          LPRINT       and LLIST, etc., require access to a printer device,
                       and this varies from one system to another. Users
                       might try OPENing the printer device on their own
                       operating system (e.g., "/dev/lp" on Unix systems,
                       or "PRN" under DOS) and see if printing can be done
                       from bwBASIC in this way.

          NULL         In this case, I am convinced that NULL is no longer
                       necessary, since very few printers now require NULLs
                       at the end of lines.

          OUT          See INP above (calls to hardware ports).

          PEEK()       PEEK and POKE enabled earlier BASICs to address
                       particular memory locations. Although bwBASIC
                       could possibly implement this command (POKE) and
                       this function (PEEK()), the limitation would be
                       highly limited by the different systems for
                       memory access in different systems.

          POKE         see PEEK() above.

          RENUM        Since unnumbered lines can be entered and
                       executed under bwBASIC, it would not be
                       possible to implement a RENUM routine.
                       Instead, bwBASIC uses DO NUM and DO UNNUM.

          RESUME       Is this possible under C? If so, I
                       simply have failed to figure it out yet.
                       Mea culpa (but not maxima).

          USR          See CALL and DEF USR above (machine language
                       subroutines).

          VARPTR       See PEEK and POKE above.

          WAIT         See INP and OUT above.

          There are other commands, functions, and implementation details
          that I am working on, and which are on the agenda list for future
          versions of bwBASIC.  These agenda include:

          PARACT       i.e., the ability to execute PARallel ACTions. This
                       is described in ANSI BASIC, although I have not seen it
                       implemented before.  It will offer a rough, non-
                       preemptive form of multitasking within the scope
                       of a BASIC program. Programmers will note points at which
                       there are already hooks for PARACT in bwBASIC.

          XMEM         PC-type computers need to be able to use extended
                       memory.  If we could use extended memory for program
                       lines, variables, and function definitions, we could
                       write much longer programs.  This would entail,
                       however, a fairly serious rewriting of the program
                       to utilize memory handles for these storage features
                       instead of direct memory pointers.

          Windows      The addition of memory handles in addition to the
                       non-preemptive execution of program lines (in a
                       crude form, already present) will make it possible
                       to develop implementations for Windows and perhaps
                       for other graphical user interfaces.  But what form
                       should this take?  I have in mind presently a BASIC
                       that would run in the background, appearing only
                       as an icon in the GUI space, with pop-up editors
                       and output windows. Thus, the interpreted language
                       would serve a purpose something like 'cron' (a task
                       scheduler) under Unix systems. You may have some
                       reflections that would help me in this.

          Graphics     Here we face fairly critical differences in different
                       styles and implementations of graphics, e.g., between
                       GWBASIC, ANSI BASIC, VisualBASIC, etc. But it's
                       possible that Graphics commands and functions could
                       be added. These would all be implementation-specific.

          The ANSI Standard for full BASIC does not specify which particular
          commands or functions must be implemented, and in fact the standard
          is very robust.  Perhaps no implementation of BASIC would ever
          include all of the items, but some ANSI commands and functions which
          remain unimplemented are:

          ACCESS
          ANGLE
          AREA
          ARITHMETIC
          ARRAY
          ASK
          BSTR
          BVAL
          CEIL
          CELLS
          CLIP
          COLLATE
          CONNECT
          COSH
          DATUM
          DEBUG
          DECIMAL
          DECLARE
          DEGREES
          DEVICE
          DISCONNECT
          DISPLAY
          DOT
          DRAW
          ERASE
          EVENT
          EXCEPTION
          GRAPH
          HANDLER
          IMAGE
          KEY
          LCASE
          LINES
          LOG10
          LOG2
          MAT
          MIX
          MULTIPOINT
          OUTIN
          OUTPUT
          PARACT
          PICTURE
          PIXEL
          PLOT
          POINTS
          RADIANS
          RECEIVE
          RENUMBER
          REWRITE
          ROTATE
          ROUND
          SEIZE
          SEND
          SHIFT
          SINH
          TANH
          TIMEOUT
          TRACE
          TRANSFORM
          TRUNCATE
          UBOUND
          UCASE
          VIEWPORT
          WAIT
          VIEWPORT
          ZONEWIDTH

       8. THE STORY OF BYWATER BASIC

          This program was originally begun in 1982 by my grandmother, Mrs.
          Verda Spell of Beaumont, TX.  She was writing the program using
          an ANSI C compiler on an Osborne I CP/M computer and although my
          grandfather (Lockwood Spell) had bought an IBM PC with 256k of
          RAM my grandmother would not use it, paraphrasing George Herbert
          to the effect that "He who cannot in 64k program, cannot in 512k."
          She had used Microsoft BASIC and although she had nothing against
          it she said repeatedly that she didn't understand why Digital
          Research didn't "sue the socks off of Microsoft" for version 1.0
          of MSDOS and so I reckon that she hoped to undercut Microsoft's
          entire market and eventually build a new software empire on
          the North End of Beaumont. Her programming efforts were cut
          tragically short when she was thrown from a Beaumont to Port
          Arthur commuter train in the summer of 1986. I found the source
          code to bwBASIC on a single-density Osborne diskette in her knitting
          bag and eventually managed to have it all copied over to a PC
          diskette. I have revised it slightly prior to this release. You
          should know, though, that I myself am an historian, not a programmer.

       9. COMMUNICATIONS:

          email:  tcamp@delphi.com

                               October 11, 1993                     BWBASIC(1)