Turbo Pascal Provides two ‘virtual’ arrays that provide acces to memory (Mem) and I/O ports (Port). To access memory we need segment and offset. Both parameters are processed and calculated. The segment is put into the ES register while offset is in DI.

This procedure processes Port and PortW statements. This stetement accesses I/O address space and generates OUT instruction. Reading from Port and PortW is done at expression processing.