82C55A
Operating Modes
Mode 0 (Basic Input Output) This functional con-
figuration provides simple input and output opera-
tions for each of the three ports No ‘‘handshaking’’
is required data is simply written to or read from a
specified port
Mode 0 Basic Functional Definitions
Two 8-bit ports and two 4-bit ports
Any port can be input or output
Outputs are latched
Inputs are not latched
16 different Input Output configurations are pos-
sible in this Mode
MODE 0 (BASIC INPUT)
MODE 0 (BASIC OUTPUT)
231256 – 8
231256 – 9
7