Einar Kjartansson began writing what is now called SU (the SY package) in the late 1970s while still a graduate student at Jon Claerbout's Stanford Exploration Project (SEP). He continued to expand the package while he was a professor at the University of Utah in the early eighties. In 1984, during an extended visit to SEP Einar introduced SY to Shuki Ronen, then a graduate student at Stanford. Ronen further developed SY from 1984 to 1986. Other students at SEP started to use it and contributed code and ideas. SY was inspired by much other software developed at SEP and benefited from the foundations laid by Claerbout and many of his students; Rob Clayton, Stew Levin, Dave Hale, Jeff Thorson, Chuck Sword, and others who pioneered seismic processing on Unix in the seventies and early eighties.
In 1986, Shuki Ronen brought this work to the CWP at Colorado School of Mines during his one year postdoctoral appointment there, Ronen aided Cohen in turning SU into a supportable and exportable product. Chris Liner (homepage), while a student at the Center, contributed to many of the graphics codes used in the pre-workstation (i.e, graphics terminal) age of SU. Liner continues to promote the use of SU in his students' research at the University of Houston. Craig Artley, now at Golden Geophysical, made major contributions to the graphics codes while still a student at CWP and continues to make significant contributions to the general package}. Dave Hale wrote several of the heavy lifting processing codes as well as most of the core scientific and graphics libraries.
John Stockwell's involvement with SU began in 1989. He was largely responsible for the Makefile structure in the package. He has been the main contact for the project since the first public release of SU in September 1992 (Release 19). After Jack Cohen's death in 1996, Stockwell assumed the role of principal investigator of the SU project and has since remained in that capacity. The number of lines of code have more than quadrupled from 1996 to 2011.
There have been many contributors to SU over the past two decades. Many CWP students, as well as geophysicists from around the globe have contributed suggestions as well as code to the package. Some codes have been written in response to frequently asked questions.