The source code of the original version of Adobe Photoshop has been made available by The Computer History Museum, based in California. Photoshop started off in the 1980s as a program called 'Display' written by Thomas Knoll, before being renamed 'Photoshop' in 1990 - the year that the first version of the software shipped to customers. The download, which is available for non-commercial use with the permission of Adobe, consists of around 128,000 lines of code.
Screenshot of the the first version of Adobe Photoshop released in 1990
The verb 'to Photoshop' is common now, but as Len Shustek - chairman of the board of trustees at the California-based museum - says in a blog post on the museum's website, 'when brothers Thomas and John Knoll began designing and writing an image editing program in the late 1980s, they could not have imagined that they would be adding a word to the dictionary.'
Homescreen showing the available tools in Photoshop V1. Note how the icons of each tool are still much the same now - 23 years after version 1 shipped.
The source code is available for non-commercial use, and you must accept a license agreement before downloading. The Computer History Museum has also provided links to the 1990 version of the Adobe Photoshop User Guide and the original Tutorial.
The first version of Photoshop allowed users to select brush color as well as size and texture.