ENEE 440 Chapter 6

8255 PPI

8255 Register Select -CS A1 A0 REGISTER R/W PORT A R/W PORT B R/W PORT C R/W CR W 1 X X8255 NOT SELECTED

8255 Interfaced to PC

8255 -to-PC Decoding Chart

8255 Register Addresses Port A300 Port B301 Port C302 Control Register303

8255 Control Word

Read in Switches and Display Output !Configuration of 8255 in mode 0 with Port A as input and Port B as output mov dx, 303h mov al, 90h out dx, al !Read Port A and send data to Port B mov dx, 300h in al, dx mov dx, 301h out dx, al