Interface circuit based on 8155 and single chip microcomputer

　　The interface circuit composed of 8155 and single-chip microcomputer is shown in the figure below.

　　According to the wiring diagram in the figure, assuming that A14~A9 are all high level, 8155 will work, so there will be:

　　Memory address: 0x7F00～0x7FFF.

　　Command/Status Register Address: 0x7E00 (There are 32 corresponding addresses, select a valid address).

　　Port A address: 0x7EO1 (There are 32 corresponding addresses, select a valid address in the period).

　　Port B address: 0x7E02 (There are 32 corresponding addresses, select a valid address in the period).

　　Port C address: 0x7E03 (There are 32 corresponding addresses, select a valid address in the period).

　　Timer register A address: 0x7E04 (there are 32 corresponding addresses, select a valid address).

　　Timer register B address: 0x7E05 (there are 32 corresponding addresses, select a valid address).