TIA 1A - TELEVISION INTERFACE ADAPTOR (MODEL 1A)
The TIA is an MOS integrated circuit designed to interface
between an eight (8) bit microprocessor and a television
video modulator and to convert eight (8) bit parallel data
into serial outputs for the color, luminosity, and
composite sync required by a video modulator.
This circuit operates on a line by line basis, always
outputting the same information every television line
unless new data is written into it by the microprocessor.
A hardware sync counter produces horizontal sync timing
independent of the microprocessor. Vertical sync timing is
supplied to this circuit by the microprocessor and combined
into composite sync.
Horizontal position counters are used to trigger the serial
output of five (5) horizontally movable objects; two
players, two missiles and a ball. The microprocessor can
add or subtract from these position counters to move these
objects right or left.
The microprocessor determines all vertical position and
motion by writing zeros or ones into object registers
before each appropriate horizontal line.
Walls, clouds and other seldom moved objects are produced
by a low resolution data register called the playfield
A fifteen (15) bit collision register detects all fifteen
possible two object collisions between these six (6)
objects (five moveable and one playfield). This collision
register can be read and reset by the microprocessor. Six
input ports are also provided on this chip that can be read
by the microprocessor. These input ports and the collision
register are the only chip addresses that can be read by
the microprocessor. All other addresses are write only.
Color luminosity registers are included that can be
programmed by the microprocessor with eight (8) luminosity
and fifteen (15) color values. A digital phase shifter is
included on this chip to provide a single color output with
fifteen (15) phase angles.
Two (2) independent audio generating circuits are included,
each with programmable frequency, noise content, and volume