Chapter 41: The Failure of Code 49 |
Brief Summary |
Code 49, introduced in 1988 by Intermec, holds the distinction of being the first two-dimensional (2D) stacked barcode symbology. It was a bold and necessary attempt to break through the data capacity limitations of traditional one-dimensional (1D) barcodes. By stacking rows of linear barcode patterns, Code 49 offered a way to encode more information into a smaller physical space. However, despite its pioneering status, Code 49 was plagued by significant practical drawbacks. Its complex structure made it difficult to print with sufficient quality, and its decoding logic was challenging for the scanning technology of the era. Crucially, within just a few years, Code 49 was superseded by the more robust and versatile PDF417 symbology. PDF417 offered superior error correction, greater data capacity, and was more easily supported by next-generation imagers. Consequently, Code 49 never achieved widespread commercial adoption. It now serves as a fascinating historical footnote, a 'first step' that illuminated the path for the successful 2D symbologies that followed. Its primary legacy is as a lesson in how a technically novel solution must also be practical, robust, and well-supported by the broader ecosystem of printers and scanners to succeed. Its most significant real-world application was in specialized scientific fields, such as entomology, where it was used for the unique labeling of biological specimens. |
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Introduction: The Dawn of the Two-Dimensional Code |
By the late 1980s, the limitations of the familiar, linear one-dimensional barcode were becoming increasingly apparent. Symbologies like the ubiquitous UPC (Universal Product Code) and Code 39 were remarkably efficient for their purpose, allowing for rapid point-of-sale scanning and inventory tracking. However, they could only hold a limited amount of data---typically 10 to 20 alphanumeric characters. As businesses and industries grew more complex, the demand to encode more information directly onto a label intensified. There was a burgeoning need to embed not just a product identifier, but also manufacturing dates, lot numbers, expiration dates, and other crucial data directly within the barcode itself, eliminating the need for a central database lookup. The question wasn't if a solution would emerge, but when and in what form. |
The answer arrived in the late 1980s from Intermec Technologies, a leading innovator in the automatic identification and data capture industry. The result was Code 49, a symbology that fundamentally broke the mold of traditional barcoding. Rather than a single, continuous row of bars and spaces, Code 49 was a 'stacked' code. It consisted of two to eight rows of linear barcodes placed directly on top of one another, separated by a small gap. This structure allowed it to encode a significantly greater amount of data in a compact area. As one source notes, it was the first of its kind: 'Intermec developed the first stacked code. 2-8 rows of Code 39-like symbols, holding up to 49 alphanumeric characters.' |
Code 49 was a conceptual breakthrough, a 'bridge' between the old world of 1D scanning and the new frontier of high-density data storage. However, while it opened a door, it was a solution that was quickly overshadowed by a more formidable successor. This chapter explores the technical characteristics of Code 49, the challenges that led to its failure, the specific niche applications it found, and its ultimate place in history as a stepping-stone to success. |
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Technical Anatomy of Code 49 |
Understanding why Code 49 failed requires understanding how it was designed. Its structure was based on a clever but ultimately flawed compromise. |
A Stacked Symbology Based on Code 39 |
At its core, Code 49 was built upon the familiar framework of Code 39, one of the most widely used alphanumeric barcodes of the time. Code 39 is a discrete symbology where each character is encoded by a pattern of five bars and four spaces, with three of the nine elements being wide. Code 49 adopted a similar logic. However, instead of encoding just one character per pattern, its rows were a series of these patterns. This design had the advantage of being somewhat familiar to developers and manufacturers, theoretically easing adoption. The rows themselves were structured in a self-contained format that utilized a specific start and stop pattern . |
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Data Capacity and Structure |
The Code 49 symbology was a continuous, variable-length code capable of encoding the full 128-character ASCII set. A Code 49 symbol could have between two and eight rows. The total data capacity was directly tied to the number of rows. A symbol with two rows could encode a maximum of 10 alphanumeric characters, while the maximum of eight rows could hold up to 49 characters . This is how it earned its name. This capacity was a significant step up from a typical Code 39 barcode, making it seem attractive for applications that needed moderate amounts of data. |
The '70 Module' Structure |
From a technical decoding perspective, Code 49 symbols have a fixed total width of 70 modules . This fixed width was critical for the decoding algorithms. Scanners and decoders used this known constant to determine the 'X-dimension,' which is the width of the narrowest bar or space in the symbol. By measuring the total width of the symbol and dividing by 70, the decoder could calculate the X-dimension and then resolve all the other elements (bars and spaces of varying widths) within the code. This inherent structure was an attempt by its designers to make the code easier to read by providing a known mathematical baseline for the decoding logic. |
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The Fundamental Flaws |
While Code 49 was a clever technical achievement, it was born with inherent weaknesses that prevented it from becoming an industry standard. These flaws were not just minor inconveniences; they were fundamental problems with print quality, reading reliability, and the technology available to support it. |
1. Printing Complexity and Tolerance Issues |
The very structure that gave Code 49 its increased data capacity---its multiple stacked rows---also created its most significant difficulty: printing. While a single-row Code 39 barcode is relatively tolerant of printing imperfections like slight ink spread or unevenness, Code 49 was not. Because the rows were stacked tightly and the decode logic relied on accurately determining the width of each bar and space to calculate the X-dimension, even minor print irregularities could cause the entire symbol to be unreadable. |
If the vertical alignment of the rows was off, or if the ink bled slightly, causing bars to become wider than intended (a common issue in thermal or dot-matrix printing), the scanner's ability to accurately parse the 70-module width and its internal elements was compromised. A failure in a single row could render the whole symbol useless, as the scan line needed to traverse all rows correctly. This demanded high-quality printing equipment and precise control over the printing process, which was not always available or cost-effective in the late 1980s and early 1990s. The technology at the time was more accustomed to the forgiving nature of linear codes. |
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2. Complexity of Decoding and Scanner Limitations |
The decoding logic for Code 49 was, by its nature, more complex than that for a linear code. The scanner couldn't just interpret a sequence of bars and spaces in a single line; it had to parse the start and stop patterns of the symbol, read each individual row, and then reconstruct the data in the correct order. This was a challenge for the first generation of laser scanners, which were the dominant technology at the time. |
Laser scanners work by sweeping a single beam of light across the barcode. To read a stacked code like Code 49, the beam had to be precisely aimed to traverse all the rows. This was a slow and error-prone process for a human operator. If the scan line wasn't perfectly aligned, it would only read one or two rows, not the entire symbol. The data from Code 49 was not simply the sum of its rows; the rows needed to be read and then reassembled in a specific sequence to form the complete message. This made reading Code 49 far more prone to operator error than reading a simple linear code. As one source describes, 'A scanner must read both data lines before decoding and returning this string.' |
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3. Limited Error Correction |
Crucially, unlike its successor PDF417, Code 49 did not include a robust error correction algorithm. While it had some check characters for each row to verify integrity, it lacked the ability to reconstruct data if a portion of the symbol was damaged, dirty, or poorly printed. In the real world, barcode labels are subject to wear and tear, smudging, and partial damage. A standard linear code can often be read if a small part is damaged; the scanner can pick up the remaining sequence. With Code 49, however, if one row was unreadable, the whole symbol typically failed. This lack of redundancy made it a fragile and unreliable choice for many commercial applications. |
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The Primary Application: A Niche in Entomology |
Given these limitations, Code 49 never found a home in mainstream retail or logistics. Its complexity and reading challenges made it unsuitable for the high-speed, high-volume environments of grocery stores or warehouses. However, it did find a fascinating and very specific niche: the world of scientific specimen labeling, specifically in entomology, the study of insects. |
The Specimen Labeling Project |
The most documented and successful use of Code 49 came from a collaboration between the Instituto Nacional de Biodiversidad (INBio) in Costa Rica and several American universities, including the University of Georgia and the University of Kansas. This project aimed to create a global biodiversity inventory by cataloging millions of insect specimens. The challenge they faced was monumental. Each specimen needed a unique, permanent, and machine-readable label that could contain a unique identifier. Handwriting or printing text labels was slow, prone to error, and made data entry into databases a tedious and error-prone task. |
Here, Code 49 proved to be a perfect match for a very particular set of requirements. Because the labels needed to be small to fit on a pin next to a tiny beetle or wasp, and because the data was simple (just a short, unique alphanumeric code), the compact nature of Code 49 was ideal. It could print more data in a smaller footprint than a linear code. As one report on the project noted, 'We label specimens with both barcodes and conventional labels... We use CODE 49 barcodes because of their small size.' |
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Institutional Identifier Strategies |
The project showcased the flexibility of Code 49's row system. Different institutions used different configurations based on their needs and budgets. The University of Kansas at Lawrence, for example, adopted a Code 49 with their institutional identifier 'KU' and just one data row. This was simple and fast to scan. In contrast, INBio used a three-row Code 49 to encode longer identifiers, allowing them to label a larger number of specimens. At the University of Georgia, they used a two-row system with the identifier 'UGCA'. As a source explains, 'INBio is using CODE 49 labels with three data lines. Thus, while KU is more limited in the number of specimens it can encode with it current label format than INBio, its labels are the most efficient to read, requiring only one encoded data line to be scanned.' |
Implementation and Scanning Challenges |
The project's documentation also highlights the practical challenges of using Code 49. They used a 1545 Bar Code Laser Scanner attached to a personal computer. The scanner was configured to act like a keyboard, making data entry simple. However, the need to precisely align the laser to read all rows was a known bottleneck. The label had to be physically scanned by an operator who had to carefully position it to ensure all the rows were read correctly. The process was manageable in a quiet laboratory setting, which further explains why Code 49 was only adopted in such controlled environments, not in the dynamic, often chaotic, world of retail or industrial logistics. |
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Why PDF417 Won: The Successor |
The story of Code 49 is inextricably linked to the story of PDF417, the symbology that would render it obsolete. Developed by Symbol Technologies in 1991, PDF417 was not just an iteration but a complete rethinking of what a stacked barcode should be. |
The Arrival of PDF417 |
Just three years after Code 49, PDF417 appeared and effectively solved all the problems that plagued its predecessor. Symbol Technologies created a far more capable stacked format, with 3 to 90 rows and a maximum data capacity of up to 1,850 characters . This alone made it vastly more powerful. But its true genius lay in its other features, which addressed Code 49's critical weaknesses. |
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Reed-Solomon Error Correction |
The most significant advancement in PDF417 was its implementation of Reed-Solomon error correction. This mathematical algorithm allows the scanner to reconstruct the data even if a portion of the symbol is missing or corrupted. If a label is torn, smudged, or partially obscured, a PDF417 scanner can still read it flawlessly. This made PDF417 incredibly robust and reliable in real-world conditions. A Code 49 label would fail under the same circumstances. This single feature is arguably the primary reason PDF417 became a global standard while Code 49 faded away. |
Superior Data Capacity and Scanner Support |
With its ability to hold up to 1850 characters, PDF417 could encode entire paragraphs of text, or even small images like a photograph of a person's face. This made it the ideal choice for applications like driver's licenses, government ID cards, and shipping labels where a vast amount of portable data is required . |
Furthermore, the scanner industry had evolved. The development of area imagers---essentially, tiny cameras---made reading stacked and 2D codes far easier. An imager 'takes a picture' of the code, and then software decodes the entire image in one go, eliminating the need for precise laser alignment. While a Code 49 could theoretically be read by these new imagers, the software industry had already standardized on PDF417 because it was more feature-rich. The support ecosystem---the combination of robust software, better scanners, and a clear industry need---propelled PDF417 to success, leaving Code 49 behind. |
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Conclusion: A Historical Footnote |
In the final analysis, Code 49 was both an important milestone and a cautionary tale. Its creation was a necessary step. It demonstrated that barcodes did not have to be a single line, that you could stack data and create a more compact, information-rich code. It proved the concept of a 2D barcode and laid the groundwork for the symbologies that would follow. |
However, it was a commercial and technical failure because it was a solution that didn't adequately consider the ecosystem in which it would have to operate. Its complexity in printing and decoding, combined with a lack of error correction, made it too fragile and difficult to use. The world was not ready to invest in the high-quality printers and specialized, careful scanning processes it required. It was a technology that was ahead of its time in concept but behind the times in practicality. |
Its own creators at Intermec might have predicted its fate. By the time Code 49 was being used in biology labs, the industry had already moved on. The rise of PDF417, supported by the growing power of digital imagers and sophisticated error correction, sealed its fate. Today, Code 49 is a historical footnote. It is remembered not for its widespread use, but for its role as the pioneer that showed the way. It was a stepping stone, a necessary failure that illuminated the pitfalls and possibilities of the future. The lessons learned from its demise directly informed the development of more successful systems, proving that in the world of technology, a brilliant idea is only as good as its ability to be implemented, supported, and trusted in the field. |
cs@easiersoft.com