The TIA (as seen by the programmer)

1.0 General Description

The TIA is a custom IC designed to create the TV picture and sound from the instructions sent to it by the microprocessor. It converts the 8 bit parallel data from the microprocessor into signals that are sent to video modulation circuits which combine and shape those signals to be compatible with ordinary TV reception. A playfield and 5 moveable objects can be created and manipulated by software.

A playfield consisting of walls, clouds, barriers, and other seldom moved objects can be created over a colored background. The 5 moveable objects can be positioned anywhere, and consists of 2 players, 2 missiles, and a ball. The playfield, players, missiles, and ball are created and manipulated by a series of registers in the TIA that the microprocessor can address and write into. Each type of object has certain defined capabilities. For example, a player can be moved with one instruction, but the playfield must be completely re-drawn in order to make it move.

Color and luminosity (brightness) can be assigned to the background, playfield, and 5 moveable objects. Sound can also be generated and controlled for volume, pitch, and type of sound. Collisions between the various objects on the TV screen are detected by the TIA and can be read by the microprocessor . Input ports which can be read by the microprocessor give the status of some of the various hand held controllers.

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