If you have a slight amout of hardware expertise, here is a simple, no-extra-parts-required, modification for the JLO parallel port which provides support for the Centronics port PAPER EMPTY status bit. This also eliminates the diode-ORed pull-down, which is, theoretically, a marginal technique (although it’s cheap and seems to work fine!). I don’t know if this is complete AERCO compatability. It does provide all the status signals required by MSCRIPT’s AERCO compatable software.
You must be able to open the Centronics connector on the printer cable. If your’s is a solder-on type, you’re in luck. IDC connectors can be managed, but they are more difficult. If you have a cable with the connectors molded on you may have to cut off the Centronics end and replace it with a solder-on type. The JLO port docs. give the pin connections. Remove the wire from pin 10, attach it to pin 12 and put the connector back together. Pin 10 is the active low ACK(nowledge) signal from the printer. It was not used in the JLO port, so we didn’t lose anything.
Remove U2, the 74LS126 IC, from its socket and solder a jumper between U2 socket pins 2 and 3. This frees a section of the ‘LS126 for our use. Bend pins 1, 2, and 3 of the ‘LS126 straight out from the IC and re-install it so the three pins do NOT enter the socket.
Now install three jumper wires between the exposed IC leads and the circuit board. Insulated 28 or 30 gauge wrapping wire is ideal. Run a jumper around the side of the circuit board from U2 socket pin 4 on the bottom of the board to pin 1 of the ‘LS126. Next, jumper pin 2 of the ‘LS126 to pin 10 of the header connector (the pin closest to the ‘LS02). Finally, run a jumper around the side of the board from pin 3 of the ‘LS126 to socket pin 17 of the ‘LS374 (where the diode anode is connected in the modification shown in the JLO port docs).
That’s all!