Adding a Second Port to the ioExtender.

Adding a Second Port to the ioExtender...

Building an Extra Serial Port for the GVP ioExtender MultiSerial and Parallel Zorro II Board for the Amiga

When the ioExtender hit the market a few years ago, many bought the card because it gave you a high performance serial port at low price. Along with the burgeoning demand for new, fast 14.4Kbps modems and their 57.6Kbps DTE speeds, most serious Amiga users bought a GVP or similar card to keep their systems from dropping packets or data. The GVP ioExtender uses a 16C552 UART, which is a dual channel 16550. One port, a DB9 is for gvpser.device unit 0, and the second is on a header connector, CN410 pin.

Of course, attaching a normal 10 pin PC style port extender won't work. Through some miracle of GVP design, the 10 pin header is wired straight through, unlike the PC style ones, and the second port option, sold for anywhere from $15-60, was simply a repinned cable!

What You Need...

DB9 IDC style crimp connector
10 pin crimp style header
10 pin wide flat ribbon cable

PC style serial port extender
DB9 IDC style crimp connector

and

Expansion plate with DB9 sized punchout
Hex nuts for DB9 plate
IDC crimper
Vise
Screwdrivers to take your Amiga apart with
Xacto knife, tin snips, and/or Dremel tool to trim if needed

How to...

Take the header and see where it goes onto the board. Find pin one, on the left of the port, key notch up towards you. Align the red strand of your ribbon cable with where pin 1 is on your header. If you don't have a red or coloured strand, take a magic marker and make one side the strand 1. Push the ribbon into the crimp teeth on the header. Crimp it with a IDC crimper. If you don't have an IDC crimper, you can use a vise. I used a Black and Decker Workmate vise table.
If you were using a PC style extender, ignore the above, and cut the existing DB9 end off. This could also be a DB25 end too. These are usually custom soldered/manufactured with a dab of epoxy inside, so they're useless.
Get the DB9 crimp connector. Place pin 1 onto the free end of the ribbon cable. Crimp the connector onto the ribbon. Pin 1 is on the left side of the DB9, looking at the connector straight.
Attach DB9 to expansion plate. If the DB9 hole is too small, use a Dremel or tinsnips to enlarge slightly for the little bit bigger crimp style connector. Reinstall.

Software Configuration...

The second port should be available like the first port as gvpser.device unit 1. Configure your dialer, term program, IP stack, as needed. Have fun!

As for the Other Ports...

How the other ports work is a mystery. Some say a MIDI add on was sold, some say it didn't make it to market, etc. Some say the expansion port has a board for it for Ethernet, some say not. Whatever it is, it's not widely found.

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