The Xerox Alto, Smalltalk, and Rewriting a Running GUI

Summary

Be sure to read the comment from Alan Kay at the bottom of the article! We succeeded in running the Smalltalk-76 language on our vintage Xerox Alto; this blog post gives a quick overview of the Smalltalk environment. One unusual feature of Smalltalk is you can view and modify the system's code while the system is running. I demonstrate this by modifying the scrollbar code on a running system. Smalltalk is a highly-influential programming language and environment that introduced the term "object-oriented programming" and was the ancestor of modern object-oriented languages.1 The Alto's Smalltalk environment is also notable for its creation of the graphical user interface with the desktop metaphor, icons, scrollbars, overlapping windows, popup menus and so forth. When Steve Jobs famously visited Xerox PARC, the Smalltalk GUI inspired him on how the Lisa and Macintosh should work.2 Our Xerox Alto running Smalltalk-76. The Alto was a revolutionary computer designed at Xerox PARC in 1973 to investigate personal computing. It introduced the GUI, high-resolution bitmapped displays, WYSIWYG editors, Ethernet, the optical mouse and laser printers to the world, among other things. I've been restoring an Alto from YCombinator, along with Marc Verdiell, Carl Claunch My full set of Alto posts is here and Marc's extensive videos of the restoration are here. The desktop Smalltalk introduced the desktop metaphor used in modern computing.3 It included overlapping windows4, multiple desktops and pop-up menus. These windows could be moved and resized with the mouse. (The biggest missing desktop feature was desktop icons, which Xerox later introduced in the Star computer.) To understand how revolutionary this was, consider that the Apple 1 microcomputer came out in 1976, displaying 24 lines of 40 uppercase characters. The mainframe and minicomputer worlds were focused around punched cards, line printers, Teletypes, and dumb CRT terminals. Alan Kay changed all this with his vision of a ...