TMT Pascal implements three predefined arrays to directly access 80x86
CPU data ports:
Port, PortW, and PortD.
Port, PortW, and PortD are one-dimensional arrays, and each element
represents a data port whose port address corresponds to its index.
Each component of Port is a Byte
Each component of PortW is a Word
Each component of PortD is a DWORD.
When a value is assigned to a component of Port, PortW or PortD, the value
is output to the selected port. When a component of Port, PortW or PortD
is referenced in an expression, its value is input from the selected port.