🚀 go-pugleaf

    If you wan't to transfer bi-directionally on a parallel port here
    is a scheme which will work.  First you need to modify a cable to
    cross the strobe and the ack line.  These are lines 1 and 10.  The
    receiving PC should get an interupt for each byte sent from the 
    transmitting PC.  An interupt will be generated if the IRQE bit (4)
    is set in the Control port.  The ACK line is usually used by a printer
    acknowledge that it has received a data byte.  This can instead be used
    by the transmitting PC to tell the receiving PC that a byte is ready
    to be read.  The receiving PC should have an interupt handler installed 
    which will fetch the data and store it once the interupt is generated.
    
    The ACK line is not directly controllable via a regular PC port, but
    the strobe line is.  If the ACK line is crossed with the strobe both
    ways then you have a method of transfering both ways.  

    The interupt handler should be installed in the interupt table. The
    direction bit should be set correctly (0 = Write, 1=Read) in the
    control port.  The ports IRQ should be unmasked via the PIC mask
    register so that interupts may come in.  Also there may be a register
    which needs to be set to enable bi-directionality on the parallel port
    This is different depending on whether you have an AT, microchannel,
    or and EISA machine.  

    Hope this helps, 

    Tim Markey