Star Tech Journal

9
STAR.TECH JOURNAL/DECEMBER 1983
VIDEODISC:
DESCRIPTION/FORMAT
Format
CA V - Constant Angular Velocity
THE VIDEODISC
General Description
The videodisc is the storage medium for the
video and audio information processed by the
videodisc player. It is a molded plastic disc
with a 30-centimeter diameter, and with a
capacity of up to 54,000 data tracks per side.
The tracks are arranged on the disc in a
continuous spiral, with information beginning
at the inner circumference of the disc and
proceeding to the outer.
Data on the videodisc exists in the form of
microscopic depressions ("pits") in the surface
of a disc side. This surface is coated with a thin
aluminum layer which, in tum, is covered with
a thin plastic coating to protect it during
subsequent manufacturing processes. In
practice, the reflective surface of the disc is
bonded to an equal thickness of aluminum to
form a more rigid disc. The videodisc player's
laser beam passes through the transparent
plastic disc material of the outer disc surface
and reads the recorded information from the
raisedreflectiveimpressions("bumps")within.
The outer plastic disc surfaces also help to
protect the reflective layer from mechanical
damage.
A videodisc formatted for CA V is designed to
rotate at a constant 1800 rpm. This format
provides up to 30 minutes of television program
material per side. Each of the 54,000 data
tracks contains one complete television frame.
Because the tracks are physically unique and
regularly spaced, individual frames can be
displayed in forward or reverse direction at
slow or normal speed. They may also be
displayed step-by-step in either direction, or in
single freeze-frame mode.
In addition to being physically distinct, each
frame is logically identified by a unique frame
number. Individual frames can thus be addressed
by the player's internal logic and accessed by
the laser. This capability makes possible many
of the user-programmable features of the
player, between noncontinuous frames, and
selected segment play.
':::E::-T::':.ull
CONSTANT ANGULAR VELOCITY (CAV)
INFORMATION LAYOUT
****************
SERVICE.
Bally Midway believes that it's our responsibility to make
your job easier. We keep your service needs in mind beginning
with our games's initial designs.
A history of conducting the industry's first service schools
is continued today through our distributors, holding service
schools all over the world. Our service manuals are specifi-
cally designed to simplify repairs and are packed in every
pin or video game we ship, saving you unnecessary time
and money locating one.
Star-Tech's reader survey speaks for us: Bally Midway is
among the leaders in service.
Get our service newsletter! Call Bally Midway's toll-free
service number: 1-800-323-7182.