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BARCODES

In "Scanning the Future with New Barcodes" (News Briefs, Jan. 2011, p. 20), 2D barcodes are presented as a relatively new technology. However, 2D barcodes have been around for at least 20 years. 1 In fact, I was involved in the creation of one of them, PDF417, at Symbol Technologies. 2

Readers most likely have encountered at least three of the 2D barcodes in their daily lives. PDF417 is used widely on drivers' licenses, vehicle registration documents, and airline boarding passes, among other applications. The US Postal Service uses Datamatrix in place of stamps, and UPS has its own code, Maxicode, with its characteristic "bull's-eye" and hexagonal grid.

Each of these codes has characteristics that make it appropriate for particular applications. For example, Datamatrix has a higher bit density than PDF417, but it requires a complete capture of the image, while PDF417 can be read with an ordinary laser scanner.

In my view, the article is too optimistic about accessing websites from barcodes in advertisements. This has been tried since the late 1990s without gaining wide acceptance, and I anticipate that this is likely to remain the case.

It is indeed troublesome to type a URL, but it's not necessary to do so. Using the Google toolbar (or similar technology), typing a few letters returns a list of likely sites. All you need then is a mouse click. Indeed, Google's indexing of letters has brought the Web within the reach of young children—that's how my six-year-old grandson accesses the LEGO.com Games.

Theo Pavlidis

t.pavlidis@ieee.org

T.PavlidisJ.SwartzandY.P.Wang"Information Encoding with Two-Dimensional Bar-Codes,"ComputerJune1992,pp. 18-28.T.PavlidisY.P.WangandJ.Swartz"High Density Two-Dimensional Bar Code Symbol,"US Patent 5,304,786,19Apr.1994.

ERRATA

In the first sentence in "Moving Toward Trustworthy Systems: R&D Essentials" (F.T. Sheldon and C. Vishik, Sept. 2010, pp. 31-40), Dennis Blair's affiliation was incorrectly noted. Blair is a former director of the Office of National Intelligence ( www.dni.gov).

In "Computational Finance" (C. Yingsaree, P. Treleaven, and G. Nuti, Dec. 2010, pp. 36-43), John Hull's Options, Futures, and Other Derivatives is incorrectly cited as providing support for the authors' computational finance taxonomy. The authors regret this error.

In "From Microprocessors to Nanostores: Rethinking Data-Centric Systems" (P. Ranganathan, Dec. 2010, pp. 39-48), errors were noted in two references. The correct citations are provided here.

M.K.Qureshiet al.,"Enhancing Lifetime and Security of PCM-Based Main Memory with Start-Gap Wear Leveling,"Proc. 42nd Ann. IEEE/ACM Int'l Symp. Microarchitecture(MICRO 42), ACM Press,2009,pp. 14-23.D.Robertset al.,Is Storage Hierarchy Dead? Co-located Compute-Storage NVRAM-Based Architectures for Data-Centric Workloads,tech. report HPL-2010-119, HP Labs,2010.
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