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Internally connecting parallel Hitachi HD44780 VFD-display

post #1 of 10
Thread Starter 

Last weekend I modified the cable that comes with the parallel VFD-display. On newer motherboards, the parallel port is removed from the backplate of the motherboard, and relocated to an internal header, like a CD or floppy drive. That was one of the reasons I went with the Gigabyte GA69GM-S2H motherboard.
To connect it to the internal pins, I took a floppy cable and pulled the wires off. This leaves the sharp connectors that connects through the isolated wires of the ribbon cable.
Examing the connections of the original VFD->Centronics cable, I noted which pins were connected to what pin of the centronics connector and made the following table:

Pin 2                    Pin 1
Black 12v               Red 12v
(disconnected)           Strobe
Data0                   Data1
Data2                   Data3
Data4                   Data5
Data6                   Data7
On the motherboard header, the pins were:
Pin 1            Pin 2
Strobe          (disconnected)
Data0           (disconnected)
Data1           Init
Data2           (disconnected)
Data3           (disconnected)
Data4           (disconnected)
Data5           (disconnected)
Data6           (disconnected)
Data7           (disconnected)
Tip: There usually is a marking on the connector/pins that indicate pin 1.

Then the connections from the VFD-connector to the floppy-connector could be made by pressing the wires into the sharp connector on top of the floppy-connector. I then soldered the 12v wires with the VFD-connector, and the cable worked somewhat. Some characters were wrong, an E were displayed as a G. By looking at the ASCII table, it could be seen that the difference was the bit 1, which meant that the connection to Data1 was bad. After reconnecting it, the display works great.

I hope this info can be of value to others using parallel VFDs. It took some hours, disassembling and reconnecting the cables. Using the tables above, you should save a considerable amount of time.
I'm happy not having the awkward connection of a parallel cable coming out of a fan hole, and into the Centronics parallel connector.

System specs:
Gigabyte GA69GM-S2H
Athlon X2 4800+, 65nm, rev. G2, 2.5 GHz
2x1024 MB Corsair XMS 800 MHz
Samsung SH-S203B/BEBN
Hitachi Deskstar T7K500, 320 GB
Dign 3se case
X-Fi Elite Pro
Abit AirPace, PCI-Express 1x, Wifi-adapter
Sapphire Theater 550 Pro
post #2 of 10
"Search" is my friend
I know this is an old post, but it was exactly what I was looking for.
post #3 of 10
when you mention "Hitachi HD44780 VFD-display", does it mean variable frequency drives (like in industrial applications)? or something else? I don't recognize any code listed.

post #4 of 10
Thread Starter 
I'm happy to hear someone could use the information

Dan: It's for a vacuum fluorescent display, but having a variable frequency drive inside your computer could probably be fun as well.
post #5 of 10
Hi, i'm about to do exactly the same thing today.

Been scratching my head for a while wondering how to do it.

Just one question.

What is connected to pin 6 (init) on the parallel header?

post #6 of 10
Thread Starter 
I don't think anything is connected to Init on the parallel port header.

The original modification is still working great on a more recent Gigabyte GA-P35-DS3R motherboard using Windows 7 and LCD Smartie.

It's configured to show time and volume, which I actually often look at the VFD to determine
post #7 of 10
thank you for the information.
post #8 of 10
off the topic question?

do you know if we can get windows 7 before october 22 release date? couple of my friends in europe already bought windows 7 there. they assure me that it is not the RC.
post #9 of 10
Originally Posted by dan_galbo View Post

does it mean variable frequency drives

LOL. A little knowledge is dangerous eh.

For those of u without a nice internal parallel header, u can do this -

OK, so u gotta add a connector to your backplate, but hey, it's clean!
post #10 of 10
Good information.

What software do you use to control this display ? Can it be used to browse titles ?
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