Data port:    00  00000000
Control port: c0  11000000
Status port:  7f  01111111
set  bit 0 to 0
read bit 0:   0
set  bit 0 to 1
read bit 0:   1
set  bit 0 to 0
read bit 0:   0
set  bit 2 to 1
read bit 2:   1
Data port:    04  00000100
set data      'a' (0x61 01100001)
Data port:    61  01100001
set control    4  (bit 2)
Control port: c4  11000100
Status port:  7f  01111111