Hello, I have two problems with Z84C1510FEC, both relate to the PIO (parallel interface), which behaves strangely. Both ports A and B are lead out only on the plug, nothing further is not connected to them, the length of wire approximately 2.5cm (1 inch), shorts and temptations are excluded.
First problem: Datasheet says that in the control word to select the mode (input, output, bidirectional, control), the value of bits D4-D5 ignored. In reality if I want to set as an output port (mode 0 or 3) must be at least one of the bits D4 or D5 log. 0, otherwise it does not set as an output port.
Second problem: If I am port A or B is set as output (mode 0 or mode 3), it can not write value 0FFH. With any other value works correctly, 0FFH not, some bits remain on the log. 0, on the other voltages are different, sometimes even changing the voltage.
Especially Problem no. 2 I consider very fundamental practically impossible to work with parallel ports.
You with some knowledge, advise you what to do?
Thank you, Petr