First developed in 1979, H-Chart was a pioneering software tool designed to generate procedural hierarchy charts from structured COBOL source code. It provided programmers with a visual representation of program logic, aiding in program comprehension and maintenance.
Sample H-Chart
*************
* *
* *
* MANAGE *
* INVENTORY *
* *
* *
*************
|
|---------------|
| |
************* *************
* * * *
* * * *
* ORDER * * TRACK *
* SUPPLIES * * STOCK *
* * * *
* * * *
************* *************
Background: The Shift to Structured Programming
Structured programming marked a revolution in software development, replacing the chaotic use of GOTO statements with clear, modular control structures. Edsger Dijkstra was among the most vocal critics of GOTO, arguing that it led to unmaintainable code. Building on this idea, Böhm and Jacopini mathematically proved that any program could be written using just three fundamental control structures: sequence, selection, and iteration—rendering GOTO unnecessary. This fundamental shift led to improved readability, maintainability, and the development of tools like H-Chart to support structured programming practices.
Overview
Developed by Nadaware, H-Chart was licensed to over 200 banks, government agencies, and large enterprises. It remained a widely used tool until 1987, helping programmers visualize procedural hierarchies in COBOL programs. Pro Cobol, another Nadaware tool, was responsible for transforming unstructured code into structured form.
Key Features
- Generated hierarchy charts from IBM/360 COBOL programs.
- Printed exclusively on paper, using low-resolution character-based graphics.
- Offered formatting options for multi-page or wall-size charts.
- Bundled with related developer tools like XREF (cross-referencing) and Pro Cobol (code restructuring).
Industry Impact
H-Chart was favorably reviewed in Computerworld and widely adopted in government and financial sectors.
Notable Clients
H-Chart was used by both Federal and State Government agencies, large financial institutions, and mega-corporations. Below is a list of some notable clients:
- Algoma Steel
- American Greetings
- Bank of Canada
- Canada Department of National Defence
- Canada Dry
- Chrysler Corporation
- Dayton-Hudsons
- Detroit Diesel Allison
- Exxon
- Federal-Mogul
- Federal Reserve Board
- Great-West Life Assurance
- K-Mart
- Lane Bryant
- Social Security Administration
- State of Nevada
- Supervalu Supermarkets
- World Vision
Structured Programming and Visual Hierarchies
The principles introduced by structured programming eliminated GOTO dependencies, allowing programs to be broken into smaller, manageable units. This approach paved the way for tools like H-Chart.
Sample COBOL Program and H-Chart Output
The following is an example of a COBOL program snippet and how H-Chart represented it:
PROCEDURE DIVISION.
PERFORM HIRE-EMPLOYEES.
STOP RUN.
HIRE-EMPLOYEES.
PERFORM SCREEN-CANDIDATES.
PERFORM SCHEDULE-INTERVIEWS 10 TIMES.
PERFORM MAKE-OFFERS.
SCREEN-CANDIDATES.
PERFORM SCREEN-EACH-CANDIDATE.
Generated H-Chart Output
*************
* *
* *
* HIRE *
* EMPLOYEES *
* *
* *
*************
|
|-------------------------------|
| | |
************* ************* *************
* * * * * *
* * * * * *
* SCREEN * * SCHEDULE * * MAKE *
* CANDIDATES* * INTERVIEWS* * OFFERS *
* * * * * *
* * * * * *
************* ************* *************
|
|
|
*************
* *
* SCREEN *
* EACH *
* CANDIDATE *
* *
* *
*************
Evolution and Legacy
As software development evolved, hierarchy charts declined in importance. Object-oriented programming, UML diagrams, and dependency graphs replaced rigid top-down hierarchies. Nevertheless, H-Chart played a critical role in bridging the gap between legacy COBOL systems and structured programming principles.
Today, while few H-Chart implementations remain, its legacy persists in modern software engineering tools that visualize program structure and dependencies.