MainframeMaster

COBOL Tutorial

COBOL REVERSE-VIDEO - Quick Reference

Progress0 of 0 lessons

Overview

REVERSE-VIDEO is a display attribute used in COBOL screen handling to display text with inverted colors, typically showing white text on a black background instead of the normal black text on white background. It is used to highlight important information.

Purpose and Usage

  • Visual emphasis - Highlight important information on screen
  • Error highlighting - Make error messages stand out
  • Status indicators - Show critical status information
  • User interface - Enhance screen readability
  • Warning display - Draw attention to warnings

Visual Effect Concept

Normal text: Hello World
REVERSE-VIDEO: Hello World
Inverted colors for emphasis

REVERSE-VIDEO creates high contrast for important information.

Syntax

REVERSE-VIDEO is used in the SCREEN SECTION to define display attributes for screen fields.

Basic Syntax

cobol
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
* Basic REVERSE-VIDEO syntax in SCREEN SECTION
SCREEN SECTION.
01  ERROR-SCREEN.
    05  ERROR-MESSAGE PIC X(50) 
        REVERSE-VIDEO.
 
* With other attributes
01  WARNING-SCREEN.
    05  WARNING-TEXT PIC X(40) 
        REVERSE-VIDEO BLINK.
 
* In PROCEDURE DIVISION
PROCEDURE DIVISION.
    DISPLAY ERROR-SCREEN
    DISPLAY WARNING-SCREEN
 
* Complete example
IDENTIFICATION DIVISION.
PROGRAM-ID. REVERSE-VIDEO-EXAMPLE.
 
ENVIRONMENT DIVISION.
CONFIGURATION SECTION.
 
DATA DIVISION.
WORKING-STORAGE SECTION.
01  ERROR-TEXT PIC X(50) VALUE "CRITICAL ERROR OCCURRED".
 
SCREEN SECTION.
01  ERROR-DISPLAY.
    05  ERROR-FIELD PIC X(50) 
        REVERSE-VIDEO FROM ERROR-TEXT.
 
PROCEDURE DIVISION.
MAIN-LOGIC.
    DISPLAY ERROR-DISPLAY
    STOP RUN.

REVERSE-VIDEO is applied to screen fields in the SCREEN SECTION.

Attribute Combinations

cobol
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
* REVERSE-VIDEO with BLINK
01  URGENT-MESSAGE.
    05  URGENT-TEXT PIC X(30) 
        REVERSE-VIDEO BLINK.
 
* REVERSE-VIDEO with UNDERLINE
01  IMPORTANT-FIELD.
    05  IMPORTANT-TEXT PIC X(20) 
        REVERSE-VIDEO UNDERLINE.
 
* Multiple attributes
01  CRITICAL-ALERT.
    05  ALERT-TEXT PIC X(40) 
        REVERSE-VIDEO BLINK UNDERLINE.
 
* Conditional REVERSE-VIDEO
01  STATUS-DISPLAY.
    05  STATUS-TEXT PIC X(15) 
        REVERSE-VIDEO WHEN STATUS-CODE = "ERROR".

REVERSE-VIDEO can be combined with other display attributes.

Practical Examples

These examples demonstrate how to use REVERSE-VIDEO effectively in different screen display scenarios.

Error Message Display

cobol
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
IDENTIFICATION DIVISION.
PROGRAM-ID. ERROR-DISPLAY.
 
DATA DIVISION.
WORKING-STORAGE SECTION.
01  ERROR-MESSAGE PIC X(60) VALUE "SYSTEM ERROR: INVALID INPUT DETECTED".
01  STATUS-CODE PIC X(10) VALUE "ERROR".
 
SCREEN SECTION.
01  ERROR-SCREEN.
    05  BLANK SCREEN.
    05  LINE 5 COLUMN 10 VALUE "ERROR MESSAGE:".
    05  LINE 6 COLUMN 10 PIC X(60) 
        REVERSE-VIDEO FROM ERROR-MESSAGE.
    05  LINE 8 COLUMN 10 VALUE "STATUS:".
    05  LINE 8 COLUMN 18 PIC X(10) 
        REVERSE-VIDEO FROM STATUS-CODE.
    05  LINE 10 COLUMN 10 VALUE "PRESS ENTER TO CONTINUE".
 
PROCEDURE DIVISION.
MAIN-LOGIC.
    DISPLAY ERROR-SCREEN
    ACCEPT OMITTED
    STOP RUN.

REVERSE-VIDEO highlights error messages for immediate attention.

Status Indicator

cobol
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
* Status display with REVERSE-VIDEO
DATA DIVISION.
WORKING-STORAGE SECTION.
01  SYSTEM-STATUS PIC X(20) VALUE "SYSTEM OFFLINE".
01  USER-ACTION PIC X(30) VALUE "PLEASE WAIT".
 
SCREEN SECTION.
01  STATUS-SCREEN.
    05  BLANK SCREEN.
    05  LINE 3 COLUMN 5 VALUE "SYSTEM STATUS:".
    05  LINE 3 COLUMN 20 PIC X(20) 
        REVERSE-VIDEO FROM SYSTEM-STATUS.
    05  LINE 5 COLUMN 5 VALUE "ACTION REQUIRED:".
    05  LINE 5 COLUMN 20 PIC X(30) 
        REVERSE-VIDEO BLINK FROM USER-ACTION.
    05  LINE 7 COLUMN 5 VALUE "PRESS ANY KEY TO CONTINUE".
 
PROCEDURE DIVISION.
SHOW-STATUS.
    DISPLAY STATUS-SCREEN
    ACCEPT OMITTED
    EXIT.

REVERSE-VIDEO with BLINK creates urgent status indicators.

Data Entry Validation

cobol
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
* Form with REVERSE-VIDEO validation
DATA DIVISION.
WORKING-STORAGE SECTION.
01  USER-NAME PIC X(30).
01  VALIDATION-ERROR PIC X(50) VALUE "INVALID USER NAME - PLEASE RE-ENTER".
 
SCREEN SECTION.
01  INPUT-FORM.
    05  BLANK SCREEN.
    05  LINE 3 COLUMN 5 VALUE "ENTER USER NAME:".
    05  LINE 3 COLUMN 22 PIC X(30) TO USER-NAME.
    05  LINE 5 COLUMN 5 PIC X(50) 
        REVERSE-VIDEO FROM VALIDATION-ERROR
        WHEN USER-NAME = SPACES.
 
PROCEDURE DIVISION.
GET-USER-INPUT.
    DISPLAY INPUT-FORM
    ACCEPT INPUT-FORM
    IF USER-NAME = SPACES
        DISPLAY INPUT-FORM
        ACCEPT INPUT-FORM
    END-IF.

REVERSE-VIDEO shows validation errors clearly.

Menu Highlighting

cobol
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
* Menu with REVERSE-VIDEO selection
DATA DIVISION.
WORKING-STORAGE SECTION.
01  MENU-CHOICE PIC X(1).
01  SELECTED-OPTION PIC X(20).
 
SCREEN SECTION.
01  MENU-SCREEN.
    05  BLANK SCREEN.
    05  LINE 3 COLUMN 10 VALUE "MAIN MENU".
    05  LINE 5 COLUMN 5 VALUE "1. PROCESS DATA".
    05  LINE 6 COLUMN 5 VALUE "2. VIEW REPORTS".
    05  LINE 7 COLUMN 5 VALUE "3. EXIT".
    05  LINE 9 COLUMN 5 VALUE "ENTER CHOICE:".
    05  LINE 9 COLUMN 18 PIC X(1) TO MENU-CHOICE.
    05  LINE 11 COLUMN 5 PIC X(20) 
        REVERSE-VIDEO FROM SELECTED-OPTION
        WHEN MENU-CHOICE = "1" OR "2" OR "3".
 
PROCEDURE DIVISION.
SHOW-MENU.
    EVALUATE MENU-CHOICE
        WHEN "1" MOVE "PROCESSING DATA..." TO SELECTED-OPTION
        WHEN "2" MOVE "VIEWING REPORTS..." TO SELECTED-OPTION
        WHEN "3" MOVE "EXITING PROGRAM..." TO SELECTED-OPTION
    END-EVALUATE
    DISPLAY MENU-SCREEN.

REVERSE-VIDEO highlights selected menu options.

Best Practices and Considerations

Understanding best practices ensures effective use of REVERSE-VIDEO in COBOL applications.

Best Practices

  • Use sparingly - Reserve for truly important information
  • Consistent application - Use the same way throughout your application
  • Combine with other attributes - Use BLINK for urgent messages
  • Test on different terminals - Ensure compatibility across platforms
  • Consider accessibility - Some users may have difficulty with high contrast
  • Document usage - Clearly define when REVERSE-VIDEO is used

Common Use Cases

Use CaseDescriptionExample
Error MessagesHighlight system errors"INVALID INPUT DETECTED"
WarningsShow important warnings"SYSTEM MAINTENANCE SCHEDULED"
Status IndicatorsDisplay system status"PROCESSING..."
Key InformationHighlight critical data"BALANCE: $1,000.00"
Menu SelectionsShow selected options"CURRENT SELECTION: OPTION 2"

Performance Considerations

  • Minimal impact - REVERSE-VIDEO has negligible performance effect
  • Display operation - Only affects screen rendering time
  • Terminal dependent - Performance may vary by terminal type
  • Batch processing - No effect in batch environments
  • Memory usage - No additional memory requirements

REVERSE-VIDEO Quick Reference

UsageSyntaxExample
Basic REVERSE-VIDEOPIC X(n) REVERSE-VIDEO05 ERROR-FIELD PIC X(50) REVERSE-VIDEO
With BLINKPIC X(n) REVERSE-VIDEO BLINK05 URGENT PIC X(30) REVERSE-VIDEO BLINK
With UNDERLINEPIC X(n) REVERSE-VIDEO UNDERLINE05 IMPORTANT PIC X(20) REVERSE-VIDEO UNDERLINE
ConditionalPIC X(n) REVERSE-VIDEO WHEN condition05 STATUS PIC X(15) REVERSE-VIDEO WHEN ERROR
Multiple attributesPIC X(n) REVERSE-VIDEO BLINK UNDERLINE05 CRITICAL PIC X(40) REVERSE-VIDEO BLINK UNDERLINE

Test Your Knowledge

1. What is the primary purpose of REVERSE-VIDEO in COBOL?

  • To reverse the order of characters in a string
  • To display text with inverted colors for emphasis
  • To reverse the order of records in a file
  • To reverse mathematical operations

2. In which COBOL section is REVERSE-VIDEO typically used?

  • DATA DIVISION
  • SCREEN SECTION
  • PROCEDURE DIVISION
  • ENVIRONMENT DIVISION

3. What is the visual effect of REVERSE-VIDEO?

  • Text appears in bold
  • Text appears in italics
  • Text appears with inverted colors
  • Text appears underlined

4. Can REVERSE-VIDEO be combined with other display attributes?

  • No, it can only be used alone
  • Yes, with other attributes like BLINK and UNDERLINE
  • Only with BLINK attribute
  • Only with UNDERLINE attribute

5. What is a common use case for REVERSE-VIDEO?

  • Highlighting error messages
  • Reversing string data
  • Mathematical calculations
  • File operations

Frequently Asked Questions

Related Concepts

SCREEN SECTION

Understanding the SCREEN SECTION for display formatting.

BLINK Attribute

Using BLINK attribute for flashing text.

UNDERLINE Attribute

Using UNDERLINE attribute for text emphasis.

Display Formatting

Complete guide to screen display formatting in COBOL.

User Interface Design

Best practices for COBOL user interface design.

REVERSED ClauseREWIND Statement