The PAL color circuit was initially an expansion card for the Apple II+ in 1979. The same circuit was built-in to the later Apple IIe and IIc models.
A novel part of the design is that the TCA650 is actually a PAL decoder chip that is meant to split a composite video signal into YPbPr components. The Apple II drives the TCA650 in reverse to generate the composite signal.
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The PAL color circuit was initially an expansion card for the Apple II+ in 1979. The same circuit was built-in to the later Apple IIe and IIc models.
A novel part of the design is that the TCA650 is actually a PAL decoder chip that is meant to split a composite video signal into YPbPr components. The Apple II drives the TCA650 in reverse to generate the composite signal.