22-09-2020, 09:35 PM
There are textbooks around about programming Z80 peripherals such as the PIO and CTC however some are missing some information about the PIO.
In addition to the xxxx1111, and xxxx0111 control words there is another being the xxxx0011 control word.
This control word is used to enable a PIO's port to enable or disable interrupts as follows:
INT_EN X X X 0 0 1 1
Thus %83 can be used to enable interrupts and %03 and can be used to disable interrupts without affecting the current PIO port configuration.
In addition to the xxxx1111, and xxxx0111 control words there is another being the xxxx0011 control word.
This control word is used to enable a PIO's port to enable or disable interrupts as follows:
INT_EN X X X 0 0 1 1
Thus %83 can be used to enable interrupts and %03 and can be used to disable interrupts without affecting the current PIO port configuration.