DriveWire is a way to connect your Dragon to a PC. It allows you to transfer files from the PC to your Dragon, or to use the PC as a virtual disk for the Dragon. A server program runs on the PC and services requests from the Dragon. Instead of a PC, a stand-alone DriveWire server like the uDW can be used.
DriveWire on the Dragon uses the printer port. On the Dragon, software is needed that can "talk" to the DriveWire server through the printer port. Operating systems like HDB-DOS and NitrOS-9 have support for DriveWire, and can use the DriveWire server as a full replacement for a normal floppy or hard disk drive. See Drivewire for dummies for how to use HDB-DOS and DriveWire.
For Dragon there is also DWLOAD - a small program that can be used to load programs from the DriveWire server without needing a disk operating system. DWLOAD can be embedded in a modified BASIC ROM, replacing the "DLOAD" command.
On the Dragon you will need an adapter to convert the printer port signals to a compatible serial port (or USB virtual serial port).
DriveWire server software
The Drivewire4 (DW4) server is a Java application and can be downloaded here: https://sites.google.com/site/drivewire4/download
A lightweight alternative is "DriveWire Lite": A reimplementation in C of the server side of the DriveWire 3 protocol: http://sourceforge.net/projects/dwlite/
There is also an open-source DriveWire server written in Python: https://github.com/6809/DwLoadServer
Drivewire4 (DW4) server usage
Just choose CoCo2 in the DriveWire4 server "Simple Config Wizard". Keep all the default selections.
If you would like to use the server under Windows without installing the JRE, use this batch file for startup:
SET JDK=%~dp0\jre SET JAVA_EXE=%JDK%\bin\java.exe "%JAVA_EXE%" -XX:+UseConcMarkSweepGC -jar DW4UI.jar --backup & pause
Download a JRE and put it into DriveWire directory together with this batch file.