Reversibility in Computer Architecture
10 March, 1980
Burton Rosenberg


The Packaged Environment

The natural environment of a few generations ago is being replaced with an environment of technology. To guess the weather of tomorrow we no longer look at the sky, we look at the TV. To toast our bread we no longer chop wood, we pop bread in the toaster. Yet the loss of knowledge about the clouds or trees is not replaced with a commensurate gain of knowledge about television and toasters. Whereas trees and clouds are organic elements of an open environment, televisions and toaster are not. They are packaged commodities in an advanced mass production based society. While the natural environment demanded understanding, the technological environment does not. Yet this environment is the one in which we live, and the quality of one's understanding of it directly relates to the quality of one's own life. It is the false belief of our consumer society that we own what we buy --- we only rent it from those that can produce it. In this way, our entire reality is increasingly on loan from the sources of production. In that these technologies are mass produced, this constitutes a powerful and unrecognized form of controlled media.

The Open Computer

The home computer, recently introduced into the mass culture market, is the two-fold purveyer of mass culture. Like the television and the toaster, it is a packaged commodity --- both its hardware and its software. But beyond that, as the cybernetic household becomes popular, the computer alone will move from environmental element to environmental curator --- will enter the home as an active participant in the use of all other commodities, and hence, in their definition. It is for this reason that the computer especially must be opened up to the user --- the natural balance between environmental understanding and existential quality be regained and made explicit. It is the aim of this thesis to define a computer architecture as rich in human interfaces as the architecture of trees, so that computer programming becomes as open and undefined a process as tree climbing.


The attributes essential to the reevaluation of the computer are variability and accessibility. The coexistence of variability and accessibility is reversibility, reversibility in this sense being the key to a rich, open computing environment. Reversibility has been noted by Piaget as the element of child development that allows the child to autonomously develop a meta-view of logic or space. Accessibility provides channels for all available information while variability insures mechanisms of high quality energy transfer through those channels to effect change.

The Computer as Media

As the computer is known by its media, its input and output, it is interesting to invert the predominance of the central processing unit over memory and terminal activities (as already witnessed in Actor and Data-Flow architectures). Traditionally, input is entered through the suggestively named terminal into the important heart of the computer to be milled about and incidentally output to the terminal user. The recent developments of microprocessors, programmable calculators and graphic devices make possible the envisioning of a computer whose CPU is a small dot, mobile and intellectually active, moving through the terminal's conceptual environment of logic nets and user defined functions. The requirements of accessibility and variability demand complete interaction and complete accessibility, beyond any afforded by time-share options, beyond any afforded by computers run by hierarchical operating systems, beyond the isolation between program and effect caused by interpreters and compilers. The computer must become its own media.