Editing TRS-80 Color Computer (section)

===PIAs===
There are two [[Peripheral Interface Adapter]] chips in all CoCo models. The PIAs are dedicated to I/O operations such as driving the internal 6-bit digital-to-analog converter, controlling the relay for the cassette motor, reading the keyboard, controlling the VDG mode pins, and accessing the [[RS-232]] serial I/O port.

The earliest CoCo models have two standard 6821 chips. Later, after changes in the keyboard design, the 6822 IIA (Industrial Interface Adapter) was used instead. The 6822 was eventually discontinued by Motorola, but was produced for Tandy as an [[application-specific integrated circuit]] with the part number SC67331P.