re pc parallel i i o erickson azure nmt edu alan erickson writes i m trying to bring in bits to a pc and would like to use interrupt driven routines without buying an io board or making a new port where can i bring in these bits lpt seems to have only a few inputs but i ve heard rumours that some lpts have bidirectional lines anybody know fer sure if any bi d lpts which boards have them i ll be running a new dx i know for sure that the everex magic i o ev a can be jumpered for a printer mode or for a general purpose bidirectional i o mode also i know for sure that the ibm technical reference says the following about the monochrome display printer adapter and the ibm parallel printer adapter it is essential that the external device not try to pull these lines referring to the data lines to ground and later if an external device should be driving data on these pins in violation of usage ground rules at the time of an input this data will be or ed with the latch contents i will accept no responsibility if you incur damages of any kind as a result of my saying i do not know for sure but i think you should be able to use a traditional parallel port as an input port by writing x to the data lines and then reading from the data lines while an external device drives them the input data will not be latched so noise could make this infeasible todd
