GW-BASIC/BASICA Keywords Not Supported in QBasic (73320)

SUMMARY

The following GW-BASIC/BASICA keywords are not supported in QBasic:

   AUTO        EDIT        MERGE         RENUM
   CONT        LIST        MOTOR         SAVE
   DEF USR     LLIST       NEW           USR
   DELETE      LOAD

The following keywords behave differently in QBasic than in BASICA:

   BSAVE       BLOAD       CALL ABSOLUTE
   CHAIN       COMMON      DECLARE
   DEFtype     DIM         DRAW
   EOF         FIELD       PLAY

MORE INFORMATION

The different behavior of the keywords in QBasic is as follows:

   Keyword           Description
   -------           -----------

   BSAVE, BLOAD      QBasic does not support the cassette device with
                     BSAVE and BLOAD, and memory locations may be
                     different.

   CALL ABSOLUTE     Assembly language programs invoked from BASICA
                     that have string arguments must be revised for
                     QBasic because QBasic string descriptors are 4
                     bytes long. The 4 bytes are the low byte and high
                     byte of the string length followed by the low
                     byte and high byte of the string address.

   CHAIN             QBasic does not allow you to specify a line
                     number with CHAIN and does not support the ALL,
                     MERGE, or DELETE options in BASICA.

   COMMON, DECLARE   QBasic does not allow executable statements to
                     appear before COMMON and DECLARE statements.

   DEFtype           If BASICA encounters a variable without an
                     explicit type (indicated by !, #, &amp;, $, or %), it
                     uses the default type set by the most recent
                     DEFtype statement. For example, the type of the
                     variable IFLAG changes from integer to single
                     precision in the following BASICA code fragment:

                        10  DEFINT I
                        20  PRINT IFLAG
                        30  DEFSNG I
                        40  GOTO 20

                     In QBasic, a variable's type cannot be changed
                     after it appears in a program.

   DIM               All arrays in BASICA are dynamic because BASICA
                     always allocates array storage while a program
                     runs. In QBasic, DIM can declare either a static
                     or dynamic array.

   DRAW, PLAY        DRAW and PLAY statements in BASICA that use
                     variables or other command strings within command
                     strings must be modified for QBasic. Use the
                     VARPTR$ function, which returns a string
                     representation of the variable's address:

                     BASICA Statement     QBasic Equivalent
                     ----------------     -----------------
                     DRAW "Xcmdstring$"   DRAW "X" + VARPTR$ (cmdstring$)
                     DRAW "TA = angle"    DRAW "TA =" + VARPTR$(angle)

   EOF               When you direct input from a file to a BASICA
                     program, EOF(0) returns true at the end of the
                     input file. In QBasic, EOF(0) returns true after
                     the next record is read past the end of the input
                     file. For example, the following program runs in
                     BASICA, but generates an "Input past end of file"
                     error message in QBasic:

                         5  WHILE NOT EOF(0)
                        10 LINE INPUT ; A$
                        15 WEND

   FIELD             When a random-access file is closed in BASICA
                     with a CLOSE or RESET statement, field variables
                     retain the last value assigned to them by a GET
                     statement. In QBasic, all field variables are
                     reset to null strings.