73CHAPTER 3 PIN FUNCTION (μPD78078 SUBSERIES)3.2.6 P50 to P57 (Port 5)These are 8-bit input/output ports. Besides serving as input/output ports, they function as an address bus.Port 5 can drive LEDs directly.The following operating modes can be specified bit-wise.(1) Port modeThese ports function as 8-bit input/output ports. They can be specified bit-wise as input/output ports withport mode register 5 (PM5). When they are used as input ports, on-chip pull-up resistors can be connectedby defining the pull-up resistor option register L (PUOL).(2) Control modeThese ports function as high-order address bus pins (A8 to A15) in external memory expansion mode. Whenpins are used as an address bus, the on-chip pull-up resistor is automatically disabled.3.2.7 P60 to P67 (Port 6)These are 8-bit input/output ports. Besides serving as input/output ports, they are used for control in externalmemory expansion mode. P60 to P63 can drive LEDs directly.The following operating modes can be specified bit-wise.(1) Port modeThese ports function as 8-bit input/output ports. They can be specified bit-wise as input or output ports withport mode register 6 (PM6).P60 to P63 are N-ch open-drain outputs. Mask ROM version can contain pull-up resistors with the maskoption.When P64 to P67 are used as input ports, on-chip pull-up resistors can be connected by defining the pull-up resistor option register L (PUOL).(2) Control modeThese ports function as control signal output pins (RD, WR, WAIT, ASTB) in external memory expansionmode. When a pin is used as a control signal output, the on-chip pull-up resistor is automatically disabled.Caution When external wait is not used in external memory expansion mode, P66 can be used asan input/output port.
