View Full Version : Parralell/serial to usb communication

Da armada
October 10th, 2013, 12:38 PM
hello, I hava a Compaq armada 7750mt that I can only communicate with a serial port or parallel port. I have a usb to serial cable that also came with a serial to parallel thing. Can I communicate with those cable with the 7750mt using serial/parallel and the newer computer with usb? Help would be appreciated. 15554

October 10th, 2013, 12:58 PM
You have a USB to 9 Pin serial cable and a 9 pin to 25 pin serial adapter. No parallel functionality there. If you can find a serial null modem cable, probably 9 pin female at both ends, you could attach one end of the null modem cable to the laptop and the other end to the USB-serial cable which in turn is connected to a modern computer. Run terminal emulation software at both ends and if you are lucky the two systems will talk to each other. It should work and I have seen it work before but I can't guarantee that it will work on your setup.

Da armada
October 10th, 2013, 01:03 PM
Sorry, no null modem cable. Any other way?

October 10th, 2013, 01:30 PM
You will need something with female connectors since your laptop probably has a 9-pin male connector and so does the USB-Serial cable. You could solder up wires to connect the two systems but that would take some time and cost more. Monoprice.com has lots of null modem cables for under $2.

I should have pointed this out in the previous post. There are USB to parallel port adapters which only work with parallel printers. So switching to a parallel cable won't help.

Other options:
Find one of those weird Parallel to Ethernet adapters and go through the network. Price about $25
Does your PCMCIA slot work? Lots of options in that case. Like network adapters or even USB on a card for use with USB-USB transfer cables.
Fix a floppy. Chicken and egg problem. There are parallel port floppy and CDRW drives which would help transfer data but you need some way to get those drivers loaded.
Or extract the hard drive and use a IDE USB adapter (dock or enclosure). Reinstall the drive when done. Price about $10 but getting the hard drive out is sometimes a bit challenging.

October 10th, 2013, 02:27 PM
I should have pointed this out in the previous post. There are USB to parallel port adapters which only work with parallel printers. So switching to a parallel cable won't help.And then again, maybe it's good that you didn't mention it because some of them are flakey and are unreliable, even with a printer attached! :-)

October 10th, 2013, 02:30 PM
Please be specific when you say "can I communicate". Do you want to transfer files and data? Or use a browser on the Armada to access the internet?

Any way you can do most of those things but as others have said you need to buy, beg, steal or borrow a NULL MODEM ADAPTOR or NULL MODM CABLE that fits between the 9-pin on the USB lead and the 9-Pin on the Armada. You don't give a location so we can't suggest specific shops but they are available for very small amounts or you can buy the bits and make one as per the instructions here:-


here is one on e-bay:-


Shipping to the UK brings the total price to around $10 so I guess the rates would be similar for many countries.

However serial networking is oh so slow. If you just want to get the data off I think a PCMCIA to CF card adaptor might be a better bet.


I have no idea if these need windows/95 adaptors but many photographers have them and spare cards as many cameras took CF cards. If it does work then you can copy the data to CF card and then load to another laptop using the same card, or a USB card reader.

Or you might want to try for a PCMCIA Ethernet adaptor. Again appear cheap, for example


but that will need drivers and if you have no floppy disk that might be fun getting drivers loaded.

**NOTE** I havn't dealt with any of the e-bay sellers mentioned above, or done any detailed checks to see if they work with your machines.