What Is a Programming Language?
The CPU expects instructions to arrive as numeric codes. These numeric codes are not easily read by human beings. A programming language is a set of English-like instructions that includes a set of rules (syntax) for putting the instructions together to create commands.
A translator changes the English-like commands into numeric codes that the computer can understand. The most common type of translator is a compiler. The compiler is a program that reads the English-like commands in a file and then creates another file containing computer-readable numeric codes or commands.
In the previous example, the CPU cannot understand the English-like instruction WAS A KEY PRESSED?, but a programming language might accept this as a valid command and translate it into codes that the CPU can recognize.
The term program is used loosely to refer to the actual application that is executed by the CPU, as well as the file of English-like commands originally written by the programmer before it was translated into the program that the CPU executes.
In strict terms, the English-like commands in a file are called source code, and the translated numeric codes placed in the output file are a runable program called executable code. The computer cannot directly execute source code as if it were a program. However, even experienced programmers will say, "I wrote a program to calculate the month-end balance." What they really mean is, "I wrote a source code file containing English-like commands that, when compiled, will produce an executable program file that, when run, will calculate the month-end balance." It is definitely easier to say, "I wrote a program."
What Is COBOL?
COBOL is a programming language especially aimed at solving business problems. You will see as you work through this book that COBOL solves a lot more than just business problems and can be used as a solution to many data processing problems.
New Term: COBOL is an acronym for Common Business Oriented Language.
NOTE: COBOL was developed by the Conference on Data Systems Languages (CODASYL), convened in 1959 by the Department of Defense. COBOL compilers became available in 1960, but they were not standardized. The American National Standards Institute (ANSI) standardized a version of COBOL in 1968. The language was revised and updated by ANSI in 1974 and again in 1985. These standards sometimes are called COBOL or COBOL-68, COBOL-74, or COBOL-85. Most compilers are now COBOL-85 standard, but there still are a few COBOL-74 versions out there. This book is written against the COBOL-85 standard, but you will have no trouble using a COBOL-74 compiler for any of the examples.
Because the year 2000 problem might be one of the reasons that you are studying this book, it is worth noting that legacy code could be written in any of the earlier COBOL standards. If you are taking this course to bring yourself up to speed for an update effort, you will need to learn the quirks and differences of the particular COBOL version that you will be working on. This book covers the core of COBOL-85 and will give you about 95% of any version of COBOL that you might work with. Throughout the book there are tips on differences that you might find in other versions of COBOL.
The future of COBOL is fairly bright. A new COBOL standard is being drafted even as I write this. This standard is intended to take COBOL into the future and certainly well beyond the year 2000. The amount of money that is being invested in correcting date problems in existing COBOL code is a sure indicator that no one is planning to dispose of COBOL in the near future.
Approximately 90% of all COBOL code runs in a character-based environment, which means that most COBOL screens are 80 columns wide by 24 or 25 characters high and do not contain graphics. Although there are versions of COBOL on the market that act in a Windows-like environment, this book is not intended to be a course in COBOL for Windows. This means that throughout the book, you will be running or executing your programs on an MS-DOS computer or in an MS-DOS window that has been opened on a Windows computer. The MS-DOS window is an 80 x 24 character window and represents the kind of display that you might see when coding COBOL on a mainframe or minicomputer.
