TOPS-20 User's Guide

Appendix D Using BASIC

After you see the @, type BASIC, and press the RETURN key. BASIC prints READY.

        @BASIC

        READY

Once BASIC prints READY, you can use any of the BASIC commands discussed in this section. You must not, however, use any TOPS-20 command or recognition input.

1. After you see READY, type NEW to enter a new file into your working area in the computer. Press the RETURN key.

                    READY
                    NEW
                    New Program Name--
   

2. After you see New Program Name--, type a name for your program, and press the RETURN key. The program name can have up to 39 letters and numbers. The following example shows using the name SQUARE for the new program name:

                    New program name--SQUARE
   
                    READY
   

3. After you see READY, begin typing your program. Type line numbers at the beginning of each line of your program. Press the RETURN key at the end of each line.

The example shows a BASIC program as it was originally entered; the program contains an error that is corrected later in this section.

        100!SQUARE.B20 - THIS PROGRAM CALCULATES A SQUAREROOT.
        200 PRINT "TYPE A NUMBER."
        300 INPUT X
        400 Y = SQR(X)
        500 PRINT "THE SQUAROOT OF ";X;" IS ";Y
        600 STOP
        700 END 

To run the program in your working area, type RUN, and press the RETURN key. You wil see the name of your program, the time, and the date. When you see READY, your program has finished running.

        RUN

        SQART.B20
        Friday, June 10, 1988 09:13:16

        TYPE A NUMBER.
         ? 45.668
        THE SQUAREOOT OF  45.668  IS  6,75781
        STOP at line 00600 of MAIN PROGRAM

        Compile time: 0.054 secs
        Run time: 0.138 secs            Elapsed time: 0:00:08

        READY

To edit the program in your working area:

1. Type the number of the line that you want to change.
2. Type the new contents of the line.
3. Press the RETURN key.

                 500 PRINT "THE SQUAREROOT OF ";X;" IS ";Y

To rename an existing BASIC program in your storage area:

1. Type RENAME.
2. Type the new program name.
3. Press the RETURN key.

                 RENAME SQART

                 READY

Now that you have changed your program, run it to make sure that it works properly.

        RUN

        SQUARE.B20
        Friday, June 10, 1988 09:11:44

        TYPE A NUMBER.
         ? 45.668
        THE SQUAREROOT OF 45.668  IS  6.75781
        STOP at line 00600 of MAIN PROGRAM

        Compile time: 0:086 secs
        Run time: 0.229 secs            Elapsed time: 0:00:10

        READY

To get a final copy of your corrected program, type LIST, and press the RETURN key.

        LIST

        SQART.B20
        Tuesday, February 6, 1988 11:03:31

        00100!SQUARE.B20 - THIS PROGRAM CALCULATES A SQUAREROOT.
        00200 PRINT "TYPE A NUMBER."
        00300 INPUT X
        00400 Y = SQR(X)
        00500 PRINT "THE SQUAREROOT OF ";X;"  IS ";Y
        00600 STOP
        00700 END

        READY

To list a single line of your program, type LIST, type the line number of the line, and press the RETURN key.

        LIST 500

        SQART.B20
        Tuesday, February 6, 1988 11:03:40

        00500 PRINT "THE SQUAREROOT OF ";X;"  IS ";Y

        READY

To run an existing BASIC program, you must do two things:

1. Move a copy of the program from your storage area into your working area.
2. Type the RUN command.

To move a copy of an existing program into your working area and run the program:

1. Type OLD.
2. Type the program name.
3. Press the RETURN key.
4. Type RUN.
5. Press the RETURN key.

            OLD FACTOR

            READY
            RUN<RET>

            FACTOR
            Tuesday, February 6, 1988 11:28:46

            FIND THE FACTORIAL OF:
             ? 6<RET>
            THE FACTORIAL OF 6 IS 720

            RUNTIME: 0.563 SECS                ELAPSED TIME: 0:00:51

            READY

To leave BASIC, type MONITOR, and press the RETURN key. When you see the @, you can type any TOPS-20 command.

        MONITOR
        @

To leave BASIC and log out automatically, type BYE.