So let's see if the ibm5150 will work with print shop.
Testing the printer gives an error.
So let's see if we can figure out where it's hanging up.
We'll set an i/o watchpoint with wpi 378,8,r and then when it hits, set al=df (ack is active low) and then printshop will continue.
After doing that we disable the watchpoint.
This diagram from art of asm shows the status register.
So going into src/devices/machine/pc_lpt.cpp and adding an xor on STATUS_ACK seems to fix the error message.
return m_cent_status_in->read() ^ STATUS_BUSY ^ STATUS_ACK;