TECHNICAL NOTES -COMPUTER PERFORMANCE/INSTALLATIONS: T.E. Batten
 

  1.    Duration:

           Infinite
 

  2.    Description:

           Computer Program, compiled to run on standard Amiga
           Generates continuous image/sound
           Once started the program is completely autonomous

           Electronic wallpaper.
           Can be situated in exhibition, reception or queuing areas
           or anywhere where a monitor with (hidden) computer can be placed
           or where (optional) video projection is possible.
           Areas are preferred where (casual) visitors may be (repeatedly)
           confronted with images over a period of time rather than
           being required to visit location specifically to view work.
           Program can be silent if required     -to avoid sound problems.
           Program does not interact with public -no extra space required.
 

  3. Personnel Requirements:

           Only those required to set up (and start) computer system.
 

  4. Estimated set up time:

           Essentially the time it takes to set up a computer system in situ.

           In principle, the programs can be transferred to the hard-disk
           and automatically started via the "start-up" file.

           If different programs are to be run on consecutive days then
           the programs are easily started manually by double clicking
           on the icons.

           In order to allow sound versions to run on Amigas with different
           processing speeds, a total of four input data may need to be
           entered via the keyboard immediately after staring the program
           (see "Sound Notes").
 

  5. Equipment Requirements For Live Performance:

           -Amiga Computer  (1200, 3000 or 4000 have been successfully used)
           -External Amplifier + Speakers (advisable for optimal sound quality)
           -Video Projection System -or Monitor
           -Projector hangup system -or Plinth (or table with cloth) for Monitor
           -Power supply and connecting cables:
                   -computer to power supply
                   -computer to monitor/projector
                   -computer to sound system and speakers
           -Mouse and Keyboard may be required to start programs,
            but should be out of sight when programs are running.
 

       Please Note:

        These are general remarks based on the presentation of a single
        (unspecified) work running on one computer. Most (recent) works
        are in fact based on a series of variations and can be presented
        on a single computer over a period of time, or on several computers
        simultaneously. Obviously, specific works may, for aesthetic reasons,
        require variations in the presentation (i.e. formal or informal
        presentation, etc..).

        Although intended for continuous operation the random configuration
        set up while initiating the procedures make it impossible to guarantee
        that in all cases a process will not degenerate to a static image.
        Should this happen then restart the process and inform the artist.

        Regrettably, the artist cannot provide hardware for the installation.
 

  6. System Preferences:

           Visual presentation can be via monitor or video projection.
           For optimal visual presentation the Amiga screen preferences
           should be set to:

                                 PAL: High Res
                        Visible Size: 640 x 256
                                      No Interlace
                                      No overscan
                                Font: Topaz 8
 

  7. Sound Notes:

        The Machine processing speed affects the sound. This sound has been
        developed on an AMIGA 3000. A faster machine may process the image
        quicker than the sound pulse -which means the sound queue can get
        too long and the whole system simply jams up (requiring a reset).

        Therefore the versions on the disk allow one to "fine tune"
        the sound according to taste and the machine speed.

           The recommended (trial) input values are placed <within these>
           the first set (on each line) give the values used in the 3000
           version and the second set (on each line) give a possible value
           for a machine approx. 10 times faster. One is free to play with
           these input values (please let me know if you discover fantastic
           values which are much better than mine).

           The first line defines <pulse Width, pulse Duration> ratios.
           These directly affect the Timbre and usually can be the same on any
           machine. Doubling the pulse Width value will double the hypothetical
           frequency which defines the potential pulse Width. Halving the pulse
           Duration value will halve the actual Duration of the pulse
           (in relation to it's Width).

           The second line defines <Constant pulse delay, Variable pulse delay>.
           The total pulse delay is a function of these two values.
           These values are machine dependant. As a guide to finding the
           correct values:

             Silent:          3000:               4000:
              input          input               input
                    1,0            2,1                 2,1
                    0,0            2,1                20,10

              a. If sound-queue jams up -increase one or more values.

                 Instead of waiting for machine to crash, depressing the
                 Right-Hand mouse button in the upper left corner of the
                 screen (the menu QUIT function) will temporally stop the
                 program without Exiting. If the sound continues after the
                 program has stopped -Delay values are too short (or possibly
                 pulse Duration is too long).

                 Obviously the Variable factor gives a statistical increase
                 and not an absolute increase.

              b. If separate pulses can be heard -decrease one or more (Delay)
                 values.
 

        Please use a separate stereo-amplifier with external speakers for
        each work if one wishes optimal sound presentation.
 
 
 

                                                         T.E. Batten
                                                   Amsterdam, March 1998