Smalltalk-72
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| Smalltalk-72 | |
|---|---|
 | |
| Name | Smalltalk-72 |
| Developer | Xerox PARC |
| Released | 1972 |
| Programming language | Assembly, Mesa |
| Platform | Alto |
| Influenced by | Smalltalk-71 |
| License | Proprietary |
Smalltalk-72 Smalltalk-72 was an experimental object-oriented programming environment developed at Xerox PARC in 1972 that introduced many ideas later associated with object-oriented programming. Conceived by a team led by Alan Kay, with contributions from Dan Ingalls, Adele Goldberg, Ted Kaehler, and Larry Tesler, Smalltalk-72 emphasized message passing, live objects, and a bitmapped display interface on the Xerox Alto. The system served as a research platform connected to projects at PARC and influenced subsequent work at institutions such as MIT, Stanford University, and companies including Apple Inc. and Microsoft.
History and Development
Development began within the research culture of Xerox PARC under the leadership of Alan Kay and collaborators including Dan Ingalls, Adele Goldberg, Ted Kaehler, Scott Wallace, and David Smith. Early demonstrations occurred on the Xerox Alto and were informed by antecedent systems like Sketchpad and the Dynabook concept. The team drew inspiration from programming language experiments at MIT Artificial Intelligence Laboratory, interactions with researchers from Stanford Artificial Intelligence Laboratory and projects at Digitally Distributed Systems, while influencing contemporaneous work at Bolt Beranek and Newman and academic groups at Carnegie Mellon University. Conferences such as the ACM SIGPLAN meetings and workshops sponsored by ARPA helped disseminate ideas to researchers at Bell Labs and Honeywell.
Language Design and Features
Smalltalk-72 introduced a pure message-passing model where computation was expressed as sending messages between objects, echoing conceptual frameworks discussed by Alan Kay, Adele Goldberg, Dan Ingalls, and Seymour Papert. The design included prototypes for object behavior and delegation similar to mechanisms explored by Gregory Chaitin and researchers at RAND Corporation. Typing was dynamic and late-bound, influenced by experimental typing discussions at Stanford University and debates presented at IFIP conferences. The environment provided a live programming model that paralleled interactive systems from MIT, leveraged the graphical display work of Butler Lampson and Charles P. Thacker, and integrated ideas about human-computer interaction championed by J.C.R. Licklider and Douglas Engelbart.
Implementation and Environment
The primary implementation ran on the Xerox Alto workstation using assembly and early systems code similar to projects at PARC led by Butler Lampson and Charles P. Thacker. The development tools included an interactive browser and code editor inspired by earlier editors at Stanford and MIT and the command paradigms discussed by Peter Deutsch and Richard Stallman. The system's bitmapped GUI built on innovations from Ivan Sutherland's Sketchpad and display hardware work at Xerox PARC; it influenced commercial environments at Apple Inc. and research implementations at DEC and Hewlett-Packard. The collaborative culture around the implementation echoed practices at MIT Media Lab and research labs like SRI International.
Influences and Legacy
Concepts from the system informed later languages and platforms including work by Adele Goldberg and Dan Ingalls on successor systems, the commercial Smalltalk-80 project, and influenced design decisions at Apple Computer during projects such as Lisa and Macintosh. Academic programs at MIT, Stanford University, Carnegie Mellon University, and University of California, Berkeley incorporated ideas from Smalltalk-72 into curricula and research. Industry influence extended to Xerox, Apple Inc., Microsoft Corporation, Sun Microsystems, and IBM; notable researchers such as Alan Kay, Dan Ingalls, Adele Goldberg, and Ted Kaehler continued to shape object-oriented discourse reflected in standards discussed at ACM and work at IEEE. The system's emphasis on live objects and GUIs contributed to paradigms used in Eiffel development and influenced user-interface research at Bell Labs and HP Labs.
Reception and Usage
Early reception among researchers at Xerox PARC, MIT, and Stanford was enthusiastic, with demonstrations at venues such as ACM SIGGRAPH and ACM SIGPLAN garnering attention from scholars like Seymour Papert and Butler Lampson. Commercial uptake was limited initially, but the ideas propagated into Smalltalk-80 and commercial software at Digitalk and ParcPlace Systems, and influenced product teams at Apple Computer and Microsoft Corporation. Publications by Adele Goldberg and others in venues associated with ACM and IEEE helped spread techniques to practitioners at Carnegie Mellon University and University of Utah, while workshops sponsored by ARPA and academic symposia at Stanford furthered adoption.
Technical Examples and Syntax
Examples in the system showcased message syntax where literals and message sends formed expressions; these demonstrations were presented in papers and talks by Alan Kay, Dan Ingalls, and Adele Goldberg at forums such as ACM SIGPLAN and ACM SIGGRAPH. Sample code fragments illustrated object creation and message chaining similar to examples later published in articles circulated at PARC, discussed in academic courses at MIT and shown in tutorials at Stanford University. Educational materials and manuals distributed within Xerox PARC and to visiting researchers at institutions like Carnegie Mellon University and University of California, Berkeley demonstrated syntax conventions and interactivity that influenced later textbooks authored by Adele Goldberg and collaborators.