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COBOL Tutorial

COBOL TERMINAL - Quick Reference

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Overview

The TERMINAL feature in COBOL provides terminal input/output operations and user interface capabilities. It enables programs to handle interactive user input, manage screen displays, and create user-friendly terminal-based applications.

Purpose and Usage

  • Terminal I/O - Handle user input and output operations
  • Screen management - Control screen display and layout
  • Cursor positioning - Position cursor at specific locations
  • User interface - Create interactive forms and menus
  • Input validation - Validate user input at the terminal

TERMINAL vs Standard DISPLAY

Standard DISPLAY: Simple output to terminal
TERMINAL: Advanced screen handling and user interaction
Result: Enhanced user interface capabilities

TERMINAL provides advanced features beyond basic DISPLAY operations.

Syntax and Usage

TERMINAL operations are implemented in the PROCEDURE DIVISION using specialized constructs for terminal input/output and screen management.

Basic TERMINAL Syntax

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* Basic TERMINAL syntax examples
       PROCEDURE DIVISION.
       
       * Terminal output with positioning
       DISPLAY "Welcome to the System" AT LINE 1 COLUMN 1
       DISPLAY "Enter your name: " AT LINE 3 COLUMN 1
       
       * Terminal input with validation
       ACCEPT USER-NAME FROM TERMINAL
       IF USER-NAME = SPACES
           DISPLAY "Name cannot be blank" AT LINE 5 COLUMN 1
       END-IF
       
       * Screen clearing and formatting
       DISPLAY SPACES AT LINE 1 COLUMN 1 ERASE EOL
       DISPLAY "Processing..." AT LINE 10 COLUMN 30
       
       * Cursor positioning
       MOVE 5 TO CURSOR-LINE
       MOVE 10 TO CURSOR-COLUMN
       DISPLAY SPACE AT LINE CURSOR-LINE COLUMN CURSOR-COLUMN

Basic TERMINAL operations for screen handling and user interaction.

Complete TERMINAL Program Example

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* Complete COBOL program demonstrating TERMINAL usage
       IDENTIFICATION DIVISION.
       PROGRAM-ID. TERMINAL-DEMO.
       
       ENVIRONMENT DIVISION.
       CONFIGURATION SECTION.
       
       DATA DIVISION.
       WORKING-STORAGE SECTION.
       01  USER-INPUT.
           05  USER-NAME     PIC X(30).
           05  USER-AGE      PIC 9(3).
           05  USER-EMAIL    PIC X(50).
       
       01  SCREEN-CONTROL.
           05  CURSOR-LINE   PIC 9(2).
           05  CURSOR-COLUMN PIC 9(2).
           05  SCREEN-STATUS PIC X.
       
       01  MENU-CHOICE      PIC X.
       
       PROCEDURE DIVISION.
       MAIN-LOGIC.
           PERFORM INITIALIZE-SCREEN
           PERFORM DISPLAY-MENU
           PERFORM PROCESS-MENU-CHOICE
           STOP RUN.
       
       INITIALIZE-SCREEN.
           * Clear screen and set up display
           DISPLAY SPACES AT LINE 1 COLUMN 1 ERASE SCREEN
           DISPLAY "=== TERMINAL APPLICATION ===" AT LINE 1 COLUMN 20
           DISPLAY "============================" AT LINE 2 COLUMN 20.
       
       DISPLAY-MENU.
           * Display main menu
           DISPLAY "1. Enter User Information" AT LINE 4 COLUMN 5
           DISPLAY "2. Display User Information" AT LINE 5 COLUMN 5
           DISPLAY "3. Exit" AT LINE 6 COLUMN 5
           DISPLAY "Enter your choice (1-3): " AT LINE 8 COLUMN 5.
       
       PROCESS-MENU-CHOICE.
           * Get user choice and process
           ACCEPT MENU-CHOICE FROM TERMINAL
           
           EVALUATE MENU-CHOICE
               WHEN "1"
                   PERFORM ENTER-USER-INFO
               WHEN "2"
                   PERFORM DISPLAY-USER-INFO
               WHEN "3"
                   PERFORM EXIT-PROGRAM
               WHEN OTHER
                   PERFORM INVALID-CHOICE
           END-EVALUATE.
       
       ENTER-USER-INFO.
           * Clear screen for user input
           DISPLAY SPACES AT LINE 1 COLUMN 1 ERASE SCREEN
           DISPLAY "=== USER INFORMATION ENTRY ===" AT LINE 1 COLUMN 15
           
           * Get user name
           DISPLAY "Enter your name: " AT LINE 3 COLUMN 5
           ACCEPT USER-NAME FROM TERMINAL
           
           * Get user age
           DISPLAY "Enter your age: " AT LINE 5 COLUMN 5
           ACCEPT USER-AGE FROM TERMINAL
           
           * Get user email
           DISPLAY "Enter your email: " AT LINE 7 COLUMN 5
           ACCEPT USER-EMAIL FROM TERMINAL
           
           * Confirm input
           DISPLAY "Information saved successfully!" AT LINE 10 COLUMN 5
           DISPLAY "Press any key to continue..." AT LINE 12 COLUMN 5
           ACCEPT SCREEN-STATUS FROM TERMINAL.
       
       DISPLAY-USER-INFO.
           * Display user information
           DISPLAY SPACES AT LINE 1 COLUMN 1 ERASE SCREEN
           DISPLAY "=== USER INFORMATION ===" AT LINE 1 COLUMN 20
           DISPLAY "Name: " USER-NAME AT LINE 3 COLUMN 5
           DISPLAY "Age: " USER-AGE AT LINE 5 COLUMN 5
           DISPLAY "Email: " USER-EMAIL AT LINE 7 COLUMN 5
           DISPLAY "Press any key to continue..." AT LINE 10 COLUMN 5
           ACCEPT SCREEN-STATUS FROM TERMINAL.
       
       INVALID-CHOICE.
           DISPLAY "Invalid choice. Please try again." AT LINE 10 COLUMN 5
           DISPLAY "Press any key to continue..." AT LINE 12 COLUMN 5
           ACCEPT SCREEN-STATUS FROM TERMINAL.
       
       EXIT-PROGRAM.
           DISPLAY "Thank you for using the application!" AT LINE 10 COLUMN 5
           DISPLAY "Goodbye!" AT LINE 12 COLUMN 5.

The program demonstrates comprehensive terminal interaction capabilities.

Advanced TERMINAL Usage

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* Advanced TERMINAL usage with screen management
       PROCEDURE DIVISION.
       
       ADVANCED-TERMINAL-OPERATIONS.
           PERFORM SETUP-ADVANCED-SCREEN
           PERFORM HANDLE-USER-INTERACTION
           PERFORM CLEANUP-SCREEN.
       
       SETUP-ADVANCED-SCREEN.
           * Set up advanced screen layout
           DISPLAY SPACES AT LINE 1 COLUMN 1 ERASE SCREEN
           DISPLAY "╔══════════════════════════════════════════╗" AT LINE 1 COLUMN 1
           DISPLAY "║           ADVANCED TERMINAL APP          ║" AT LINE 2 COLUMN 1
           DISPLAY "╠══════════════════════════════════════════╣" AT LINE 3 COLUMN 1
           DISPLAY "║                                          ║" AT LINE 4 COLUMN 1
           DISPLAY "║                                          ║" AT LINE 5 COLUMN 1
           DISPLAY "║                                          ║" AT LINE 6 COLUMN 1
           DISPLAY "║                                          ║" AT LINE 7 COLUMN 1
           DISPLAY "║                                          ║" AT LINE 8 COLUMN 1
           DISPLAY "╚══════════════════════════════════════════╝" AT LINE 9 COLUMN 1.
       
       HANDLE-USER-INTERACTION.
           * Position cursor and get input
           MOVE 5 TO CURSOR-LINE
           MOVE 5 TO CURSOR-COLUMN
           DISPLAY "Enter data: " AT LINE CURSOR-LINE COLUMN CURSOR-COLUMN
           
           * Get user input with validation
           ACCEPT USER-INPUT FROM TERMINAL
           
           * Validate input
           IF USER-INPUT = SPACES
               DISPLAY "Error: Input cannot be blank" AT LINE 10 COLUMN 5
               DISPLAY "Press any key to retry..." AT LINE 11 COLUMN 5
               ACCEPT SCREEN-STATUS FROM TERMINAL
               PERFORM HANDLE-USER-INTERACTION
           END-IF.
       
       CLEANUP-SCREEN.
           * Clean up screen before exit
           DISPLAY SPACES AT LINE 1 COLUMN 1 ERASE SCREEN
           DISPLAY "Application completed successfully!" AT LINE 10 COLUMN 10.

Advanced TERMINAL usage with sophisticated screen management.

Common Use Cases

TERMINAL is essential in various scenarios where interactive user interfaces and terminal-based applications are required.

Interactive Forms

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* Interactive forms using TERMINAL
       IDENTIFICATION DIVISION.
       PROGRAM-ID. INTERACTIVE-FORMS.
       
       DATA DIVISION.
       WORKING-STORAGE SECTION.
       01  FORM-DATA.
           05  CUSTOMER-NAME    PIC X(30).
           05  CUSTOMER-ADDRESS PIC X(50).
           05  CUSTOMER-PHONE   PIC X(15).
           05  CUSTOMER-EMAIL   PIC X(40).
       
       PROCEDURE DIVISION.
       MAIN-LOGIC.
           PERFORM DISPLAY-FORM-HEADER
           PERFORM GET-CUSTOMER-NAME
           PERFORM GET-CUSTOMER-ADDRESS
           PERFORM GET-CUSTOMER-PHONE
           PERFORM GET-CUSTOMER-EMAIL
           PERFORM CONFIRM-ENTRY
           STOP RUN.
       
       DISPLAY-FORM-HEADER.
           DISPLAY SPACES AT LINE 1 COLUMN 1 ERASE SCREEN
           DISPLAY "=== CUSTOMER INFORMATION FORM ===" AT LINE 1 COLUMN 10
           DISPLAY "==================================" AT LINE 2 COLUMN 10.
       
       GET-CUSTOMER-NAME.
           DISPLAY "Customer Name: " AT LINE 4 COLUMN 5
           ACCEPT CUSTOMER-NAME FROM TERMINAL
           IF CUSTOMER-NAME = SPACES
               DISPLAY "Name is required!" AT LINE 15 COLUMN 5
               PERFORM GET-CUSTOMER-NAME
           END-IF.
       
       GET-CUSTOMER-ADDRESS.
           DISPLAY "Customer Address: " AT LINE 6 COLUMN 5
           ACCEPT CUSTOMER-ADDRESS FROM TERMINAL.
       
       GET-CUSTOMER-PHONE.
           DISPLAY "Customer Phone: " AT LINE 8 COLUMN 5
           ACCEPT CUSTOMER-PHONE FROM TERMINAL.
       
       GET-CUSTOMER-EMAIL.
           DISPLAY "Customer Email: " AT LINE 10 COLUMN 5
           ACCEPT CUSTOMER-EMAIL FROM TERMINAL.
       
       CONFIRM-ENTRY.
           DISPLAY "Review your information:" AT LINE 12 COLUMN 5
           DISPLAY "Name: " CUSTOMER-NAME AT LINE 13 COLUMN 5
           DISPLAY "Address: " CUSTOMER-ADDRESS AT LINE 14 COLUMN 5
           DISPLAY "Phone: " CUSTOMER-PHONE AT LINE 15 COLUMN 5
           DISPLAY "Email: " CUSTOMER-EMAIL AT LINE 16 COLUMN 5.

Interactive forms use TERMINAL for user data entry and validation.

Menu-Driven Applications

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* Menu-driven application using TERMINAL
       IDENTIFICATION DIVISION.
       PROGRAM-ID. MENU-APPLICATION.
       
       DATA DIVISION.
       WORKING-STORAGE SECTION.
       01  MENU-SELECTION    PIC X.
       01  CONTINUE-FLAG     PIC X VALUE 'Y'.
       
       PROCEDURE DIVISION.
       MAIN-LOGIC.
           PERFORM UNTIL CONTINUE-FLAG = 'N'
               PERFORM DISPLAY-MAIN-MENU
               PERFORM GET-MENU-SELECTION
               PERFORM PROCESS-SELECTION
           END-PERFORM
           STOP RUN.
       
       DISPLAY-MAIN-MENU.
           DISPLAY SPACES AT LINE 1 COLUMN 1 ERASE SCREEN
           DISPLAY "╔══════════════════════════════════════════╗" AT LINE 1 COLUMN 1
           DISPLAY "║              MAIN MENU                   ║" AT LINE 2 COLUMN 1
           DISPLAY "╠══════════════════════════════════════════╣" AT LINE 3 COLUMN 1
           DISPLAY "║  1. File Operations                      ║" AT LINE 4 COLUMN 1
           DISPLAY "║  2. Data Processing                      ║" AT LINE 5 COLUMN 1
           DISPLAY "║  3. Report Generation                    ║" AT LINE 6 COLUMN 1
           DISPLAY "║  4. System Configuration                 ║" AT LINE 7 COLUMN 1
           DISPLAY "║  5. Exit                                 ║" AT LINE 8 COLUMN 1
           DISPLAY "╚══════════════════════════════════════════╝" AT LINE 9 COLUMN 1
           DISPLAY "Enter your choice (1-5): " AT LINE 11 COLUMN 5.
       
       GET-MENU-SELECTION.
           ACCEPT MENU-SELECTION FROM TERMINAL.
       
       PROCESS-SELECTION.
           EVALUATE MENU-SELECTION
               WHEN "1"
                   PERFORM FILE-OPERATIONS
               WHEN "2"
                   PERFORM DATA-PROCESSING
               WHEN "3"
                   PERFORM REPORT-GENERATION
               WHEN "4"
                   PERFORM SYSTEM-CONFIGURATION
               WHEN "5"
                   MOVE 'N' TO CONTINUE-FLAG
               WHEN OTHER
                   PERFORM INVALID-SELECTION
           END-EVALUATE.
       
       FILE-OPERATIONS.
           DISPLAY "File Operations selected" AT LINE 13 COLUMN 5
           DISPLAY "Press any key to continue..." AT LINE 14 COLUMN 5
           ACCEPT MENU-SELECTION FROM TERMINAL.
       
       DATA-PROCESSING.
           DISPLAY "Data Processing selected" AT LINE 13 COLUMN 5
           DISPLAY "Press any key to continue..." AT LINE 14 COLUMN 5
           ACCEPT MENU-SELECTION FROM TERMINAL.
       
       REPORT-GENERATION.
           DISPLAY "Report Generation selected" AT LINE 13 COLUMN 5
           DISPLAY "Press any key to continue..." AT LINE 14 COLUMN 5
           ACCEPT MENU-SELECTION FROM TERMINAL.
       
       SYSTEM-CONFIGURATION.
           DISPLAY "System Configuration selected" AT LINE 13 COLUMN 5
           DISPLAY "Press any key to continue..." AT LINE 14 COLUMN 5
           ACCEPT MENU-SELECTION FROM TERMINAL.
       
       INVALID-SELECTION.
           DISPLAY "Invalid selection. Please try again." AT LINE 13 COLUMN 5
           DISPLAY "Press any key to continue..." AT LINE 14 COLUMN 5
           ACCEPT MENU-SELECTION FROM TERMINAL.

Menu-driven applications use TERMINAL for user navigation and selection.

Data Entry Applications

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* Data entry application using TERMINAL
       IDENTIFICATION DIVISION.
       PROGRAM-ID. DATA-ENTRY-APP.
       
       DATA DIVISION.
       WORKING-STORAGE SECTION.
       01  EMPLOYEE-RECORD.
           05  EMP-ID         PIC 9(6).
           05  EMP-NAME       PIC X(30).
           05  EMP-DEPT       PIC X(20).
           05  EMP-SALARY     PIC 9(8)V99.
       
       01  ENTRY-STATUS      PIC X.
       
       PROCEDURE DIVISION.
       MAIN-LOGIC.
           PERFORM UNTIL ENTRY-STATUS = 'Q'
               PERFORM DISPLAY-ENTRY-SCREEN
               PERFORM GET-EMPLOYEE-DATA
               PERFORM VALIDATE-EMPLOYEE-DATA
               PERFORM SAVE-EMPLOYEE-DATA
               PERFORM ASK-CONTINUE
           END-PERFORM
           STOP RUN.
       
       DISPLAY-ENTRY-SCREEN.
           DISPLAY SPACES AT LINE 1 COLUMN 1 ERASE SCREEN
           DISPLAY "=== EMPLOYEE DATA ENTRY ===" AT LINE 1 COLUMN 15
           DISPLAY "============================" AT LINE 2 COLUMN 15.
       
       GET-EMPLOYEE-DATA.
           DISPLAY "Employee ID: " AT LINE 4 COLUMN 5
           ACCEPT EMP-ID FROM TERMINAL
           
           DISPLAY "Employee Name: " AT LINE 6 COLUMN 5
           ACCEPT EMP-NAME FROM TERMINAL
           
           DISPLAY "Department: " AT LINE 8 COLUMN 5
           ACCEPT EMP-DEPT FROM TERMINAL
           
           DISPLAY "Salary: " AT LINE 10 COLUMN 5
           ACCEPT EMP-SALARY FROM TERMINAL.
       
       VALIDATE-EMPLOYEE-DATA.
           IF EMP-ID = 0
               DISPLAY "Error: Invalid Employee ID" AT LINE 12 COLUMN 5
           END-IF
           
           IF EMP-NAME = SPACES
               DISPLAY "Error: Name is required" AT LINE 13 COLUMN 5
           END-IF
           
           IF EMP-SALARY <= 0
               DISPLAY "Error: Invalid salary" AT LINE 14 COLUMN 5
           END-IF.
       
       SAVE-EMPLOYEE-DATA.
           DISPLAY "Employee data saved successfully!" AT LINE 16 COLUMN 5.
       
       ASK-CONTINUE.
           DISPLAY "Enter another employee? (Y/N/Q): " AT LINE 18 COLUMN 5
           ACCEPT ENTRY-STATUS FROM TERMINAL.

Data entry applications use TERMINAL for structured data input and validation.

Best Practices and Tips

Following these best practices ensures effective use of TERMINAL in COBOL applications for better user experience and interface design.

TERMINAL Best Practices

  • Design user-friendly interfaces - Create clear, intuitive screen layouts
  • Implement input validation - Validate user input to prevent errors
  • Use consistent formatting - Maintain consistent screen layouts and styling
  • Handle errors gracefully - Provide clear error messages and recovery options
  • Provide navigation help - Include clear instructions and help information
  • Test with different terminals - Ensure compatibility across different terminal types

Screen Design Guidelines

AspectGuidelineExample
LayoutUse consistent positioning and spacingLabels at column 5, input at column 20
HeadersClear titles and section headers"=== CUSTOMER ENTRY FORM ==="
PromptsClear, descriptive prompts"Enter customer name: "
Error MessagesSpecific, helpful error messages"Name cannot be blank"
NavigationClear menu options and instructions"Press any key to continue..."

Input Validation Strategies

  • Required field validation - Check for empty or blank inputs
  • Data type validation - Ensure correct data types (numeric, alphabetic)
  • Range validation - Check values within acceptable ranges
  • Format validation - Validate specific formats (email, phone)
  • Business rule validation - Apply business-specific validation rules
  • Error recovery - Provide options to retry or correct input

TERMINAL Quick Reference

AspectDescriptionExample
LocationPROCEDURE DIVISIONIn terminal I/O operations
OutputDISPLAY with positioningDISPLAY "Text" AT LINE 5 COLUMN 10
InputACCEPT from terminalACCEPT variable FROM TERMINAL
Screen ControlClear and format screenDISPLAY SPACES ERASE SCREEN
Cursor ControlPosition cursor on screenAT LINE 10 COLUMN 15

Test Your Knowledge

1. What is the primary purpose of TERMINAL in COBOL?

  • To define arithmetic operations
  • To handle terminal input/output operations and user interface interactions
  • To control file operations
  • To define data types

2. Where is TERMINAL typically used in a COBOL program?

  • In the DATA DIVISION for terminal data definitions
  • In the PROCEDURE DIVISION for terminal I/O operations
  • In the ENVIRONMENT DIVISION for system configuration
  • In the IDENTIFICATION DIVISION

3. What types of operations can TERMINAL handle?

  • Only file operations
  • Only database operations
  • Terminal input/output, screen handling, user interface, and interactive operations
  • Only mathematical calculations

4. How does TERMINAL differ from standard DISPLAY operations?

  • They are identical in function
  • TERMINAL provides more advanced screen handling and user interaction capabilities
  • TERMINAL only works with numeric data
  • Standard DISPLAY is more advanced than TERMINAL

5. Which of the following is a common use of TERMINAL?

  • File sorting operations
  • Interactive user interfaces, screen forms, and terminal-based applications
  • Database operations
  • Mathematical calculations

Frequently Asked Questions

Related Concepts

Screen Handling

Understanding screen management in COBOL.

User Interface Design

Designing user-friendly interfaces in COBOL.

Input Validation

Validating user input in COBOL applications.

Interactive Applications

Creating interactive COBOL applications.

Terminal Operations

Working with terminal operations in COBOL.

SYSTEM-DEFAULTTEST