939Chapter 20 Port FunctionsUser’s Manual U16580EE3V1UD0020.3.12 Port ALPort AL is a 16-bit I/O port that can be set to input or output mode in 1-bit units. When the higher 8 bitsof port AL are used as port ALH (PALH) and the lower 8 bits as port ALL (PALL), port AL becomes two8-bit ports that can be set in the input or output mode in 1-bit units.(1) Functions• Input/output data can be specified in 1-bit units by using the port register AL (PAL).• Input or output mode can be set in 1-bit units by using the port mode register AL (PMAL).• Port mode or control mode (for alternate function) can be specified in 1-bit units by using theport mode control register AL (PMCAL).Table 20-15: Alternate Function Pins and Port Types of Port ALNote: Alternate function not available on μPD70F3447.Caution: On the μPD70F31187, in single-chip mode 1 or in ROM-less mode, this port has exter-nal address bus function only. Reprogramming of port AL to port mode is not possi-ble in these modes. Reading and writing of the port register PAL and port moderegister PMAL is possible but has no effect. Reading of the port mode control regis-ter PMCAL is possible and the result is always FFFFH. Writing of the port mode con-trol register PMCAL is not possible.Port Alternate Function Remark Port TypePort AL PAL0toPAL15A0 to A15Note External address busNote 1
