Jameco Electronics 3000 User Manual

The following registers are described in Table 9-8 and in Table 9-9.

PDDR—Parallel Port D data register. Read/Write.

PDDDR—Parallel Port D data direction register. A "1" makes the corresponding pin an 
output. Write only.

PDDCR—Parallel Port D drive control register. A "0" makes the corresponding pin a 
regular output. A "1" makes the corresponding pin an open-drain output. Write only.

PDFR—Parallel Port D function control register. This port may be used to make port 
positions 4 and 6 be serial port outputs. Write only.

PDBxR—These eight registers may be used to set outputs on individual port positions.

PDCR—Parallel Port D control register. This register is used to control the clocking of 
the upper and lower nibble of the final output register of the port. On reset, bits 0, 1, 4, 
and 5 are reset to zero.