BASIC LANGUAGE

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FROM CLARKSVILLE COMMODORE
      USERS GROUP


 BASIC Beginners All purpose Symbolic Instructional Code,   was developed in 1963 by John G. Kemeny and Thomas E. Kurtz at Dartmouth University for use with a time sharing computer system developed by General Electric. BASIC is the most used computer language. At one time BASIC was the first Computer language taught in Computer Science classes because of its relative simplicity and similarity to plain English. BASIC is a High Level computer language,  that is,  it is a language that is people oriented rather than a machine oriented language.    Machine Language BASIC as used on the C 64 is an Interpreted language,  each Command in BASIC calls upon one or more built in Machine Language routines during execution. Interpreted languages are much slower in execution than Machine language because of this. BASIC can be Compiled using a special program called a Compiler. A Compiler scans the BASIC language program,  converts it to Machine Code and re writes the program back to the mass storage device in compiled form. A Compiled Program can RUN on the order of 100 times faster than the Interpreted version. The original BASIC Program is called the Source Code and the Compiled version is the Object Code. 
     Now a days BASIC has fallen from favor with Colleges and PASCAL is generally taught as the first Computer language. PASCAL is a highly structured language,  that is,  the structure of the program is very rigid. 

EXAMPLE 
All Variable names and Variable types that are going to be used in the program must be declared at the beginning of the program:     
    VAR
     EMPLNO INTEGER HOURS RATE REAL 
     P BOOLEAN 
     C CHAR 

other parts of the PASCAL program are equally rigid in structure. One of the reasons to teach PASCAL rather than BASIC is because computer programming is a highly logical occupation and rigidly structured languages force the programmer to think through the problem carefully before writing the program.     

Also the structure of the program makes it self documenting.      Microsoft BASIC Version 2.0, the language used by the C 64 contains over 70 different Commands. The possible number of ways of combining these Commands is so large that my computer cannot calculate it. One of the things to take into account when writing a computer program is whether to make it transportable or not. Consider the simple task of clearing the screen,  you can clear it by typing:    

   10 PRINT Reverse Video Heart 

If you use this method and later want to make your program RUN on a different manufacturers computer it will have to be changed.      You can also Clear the Screen by typing:    

   10 PRINT CHR 147,  

If you use this method this line will run on any manufacturers computer.     

To make your programs more transportable use the ASCII CHAR for control
functions where possible and avoid using PEEKS and POKES because the addresses are different on different machines.