Port 6 - NEC mPD780973 Series Preliminary User's Manual

5.2.7 Port 6

Port 6 is a 2-bit input/output port with output latch. P60 and P61 pins can specify the input mode/output mode
in 1-bit units with the port mode register 6 (PM6).
Alternate functions include clock output and sound generator output.
RESET input sets port 6 to input mode.
Figure 5-8 shows a block diagram of port 6.
RD
WR
PORT
WR
PM
PM : Port mode register
RD : Port 6 read signal
WR : Port 6 write signal
CHAPTER 5 PORT FUNCTIONS
Figure 5-8. P60 and P61 Block Diagram
Selector
Output latch
(P60, P61)
PM60, PM61
Alternate
functions
P60/PCL/SGOA
P61/SGO/SGOF
81