Interface circuit between DAC1210 and 8-bit CPU

It is the interface circuit between DAC1210 and 8-bit CPU . In order to use the 8-bit data lines D0-D7 to transmit the 12-bit converted number (DIO
-DI11), the CPU needs to transmit the converted number in two times. First, the lower 4 bits (DI3~DIO) of the converted number are transferred to the lower j|-bit input register , then the upper 8 bits (DIl1-DI4) are transferred to the 8-bit register, and finally the status of
the 12-bit input register is transferred to the 12-bit input register . The bit DAC is converted to Shun and
the D/A conversion is started.