The first `personal imaging' prototype, designed and built by the author (Fig 2),
Figure 2: Evolution of author's `existential computing' and `personal imaging' inventions. (1980) apparatus was somewhat cumbersome. The bulky 1.5 inch Cathode Ray Tube (CRT) required a helmet for support, and provided only enough resolution for low-quality greyscale imagery or 40 letters of text per row. Later, a waist-mounted television was found to be less cumbersome, but failed to provide constancy of user-interface. Note the electronic flash, used for lightpainting, also has the built in ``keyboard'' (seven microswitches in the handle). With the advent of miniature CRTs in the late 1980s, a comfortable eyeglass-based system became practical. Presently, the author has designed and built the apparatus into ordinary eyeglasses and ordinary clothing (Late 1990s)
comprised a modular personal, wearable, multimedia computer system together with one or more cameras, a head-mounted display, and other sensors (one or more microphones, A/D converter for voltage measurement, two wearable radar systems, etc.), connected wirelessly to a separate base-station which later formed the gateway to the Internet. The modular nature of the system allowed portions to be left out or included, depending on the occasion.
Ivan Sutherland described a head-mounted display with half-silvered mirrors so that the wearer could see a virtual world superimposed on reality. Sutherland's work, as well as more recent related work  is characterized by its tethered nature (tethered to a workstation which is generally powered from an AC outlet). In this sense it differs from the proposed `personal imaging' paradigm which is based on a rig that is entirely battery operated and tetherless (e.g. includes wireless communications).
Other very recent work in wearable computing provides a task-specific system, in particular, a repair manual for use by soldiers. To make use simple, and to keep the soldier focused on the task at hand, the only input is a knob and pushbutton, so that menu items from a specific program may be selected.
The `personal imaging' effort differed from the more recent research on what might be best described as ``employer-owned technology'', or technology controlled by an external entity. In particular, the proposed user-interface paradigm is based on technology owned, operated, and controlled by the wearer --- technology that becomes part of the wearer's day-to-day lifestyle, and ``gets to know'' the wearer ``intimately''. The importance of this difference/distinction is detailed in .