In Portapak, a touchscreen is inset within the cover of a road case.
The images consists in hi-8 video footage of the train journey from
Ottawa to Montréal, which is about 2hrs or the length of a video
tape set to 'ep'. The camera was pointed outside the passenger
cart window, effectively creating a 2 hour linear traveling sequence
Surface effects occur that abstracts the images through the
recurrence of objects close to the camera while open areas in
the camera field read as a slowing down relative to the observer's
position. The screen is placed in a context that hints at the
portability of the apparatus. Indeed, the case originally contained
a portapak-like camera, batteries and tape recorder unit. Touching
the screen affects the speed and direction of the playback,
revisiting the A to B of linear editing systems. Our very perception
of the landscape between cities is transformed into that of an
extended palindrome.

Woody Vasulka recounts the introduction of tape to video in a short
text on the ars electronica website:

With the invasion of tape on the scene it took some time to settle
the problem of exhibition. Speaking to Steina about reel to reel
machines Bruce Nauman put it more directly: "I almost dropped
video when tape was introduced; when the tape ran out there
was no one in the gallery to rewind it, thread it and run it again.