gbooch (323588) writes "The Computer History Museum in Mountain View, California, is not just a museum of hardware, but also of software. The Museum has made public such gems as the source code for MacPaint, Photoshop, and APL, and now code from the Apple II. As their site reports:
gbooch writes "With the permission of Adobe Systems, the Computer History Museum has made available the source code for Photoshop version 1.0.1, comprising about 128,000 lines code within 179 files, most of which is in Pascal, the remainder in 68000 assembly language.
MacPaint was written by Bill Atkinson, a member of the original Macintosh development team. Originally called MacSketch, he based it on his earlier LisaSketch (also called SketchPad) for the Apple Lisa computer. Bill started work on the Macintosh version in early 1983. He also created QuickDraw (then called LisaGraf) for the Lisa. Andy Herzfeld, another key member of the team, considers QuickDraw "the single most significant component of the original Macintosh technology" in its ability to "push pixels around in the frame buffer at blinding speeds to create the celebrated user interface."
MacPaint was released with the Macintosh in January, 1984. The application was written in Apple Pascal and was packaged in a single file of only 5,822 SLOC, together with an additional 3,583 lines of assembly code for the underlying Motorola 68 microprocessor, used to implement routines needing high performance as well as certain interfaces to the operating system. QuickDraw was the Macintosh library for creating bit-mapped graphics and was used by MacPaint and other applications, and consisted of a total of 17,11 lines of 68 assembly code packaged in 36 files." Link to Original Source