Photoshop Origins:
Thomas and John Knoll developed an image editing program in the late 1980s called “Display,” which became “Photoshop.” Adobe licensed it in 1989, leading to its commercial release in 1990. The source code for version 1.0.1, primarily in Pascal, is now available for non-commercial use, showcasing its architectural sophistication and historical significance in software development.
https://computerhistory.org/blog/adobe-photoshop-source-code/