The DeskJet thermal inkjet printer was introduced in February 1988 and represents a landmark in printing technology. The DeskJet pen is the culmination of seven years of linked projects involving market research, product, process, ink, and assembly development. We have introduced three inkjet architectures since 1984 they are summarized in figure 1. Two contributions stand out for the DeskJet pen. First is unquestioned letter quality shown in figure 2c and second is its ability to print on plain paper. A brief look at the history of the DeskJet program will explain why we arrived at 300 DPI printing, however; by far the most critical and difficult issue for the DeskJet pen was the decision to print on plain paper. Following is a brief history of the DeskJet pen and a discussion of some of the critical issues in its development.