
9.3.12   Port C and Port D –  Functionality and Structure
Ports C and D are identical in function and structure and each can be configured to perform 
one or more of the following operating modes: 
J
 Standard MCU I/O Mode
J
 PLD Input  –  direct input to ZPLD 
(PSD4XXA2  and ZPSD4XXA2 Only)
J
 Address Out  –  latched address outputs
– Port C: A[0-7] are assigned to pins PC[0-7]
– Port D: A[0-7] for 8-bit multiplexed bus or A[8-15] for 16-bit multiplexed
bus are assigned to pins PD0-7]
J
 Data Port
– Port C: D[0-7] for 8-bit non-multiplexed bus
– Port D: D[8-15] for 16-bit non-multiplexed bus
J
 Open Drain  –  select CMOS or Open Drain driver
Figures 29 and 30 show the structure of a Port C or D pin. If the pin is configured as output 
port, the multiplexer selects one of the two inputs as output. If the pin is configured as input,
the input connects to :
J
 Data In Register as input in the Standard MCU I/O Mode
or
J
 ZPLD input (PSD4XXA2 and ZPSD4XXA2 Only)
9.3.13   Port E  –   Functionality and Structure
Port E can be configured to perform one or more of the following functions:
J
 Standard MCU I/O Mode
J
 PLD I/O  (PSD4XXA2 and ZPSD4XXA2 Only)
J
 Address Out  –  latched address lines A[0-7] are assigned to pins PE[0-7]
J
 Alternate Function In  –  in this mode, the inputs to Port E pins are:
–
 PE0
BHE or PSEN or WRH or UDS or SIZ0
–
 PE1
 –  ALE
–
 PE7
APD CLK  :clock input for Automatic Power Down Counter
Figure 31 shows the structure of a Port E pin. The Control Logic block selects one of four
sources through the multiplexer for pin output. If the pin is configured as input, the input
goes to:
J
 Data In Register as input in Standard MCU I/O Mode
or
J
 PE Macrocell as PLD input (PSD4XXA2 and ZPSD4XXA2 Only)
or
J
 Alternate Function In
PSD4XX Famly
57
The PSD4XX
Architecture 
(cont.)