Monthly Archives: May 2016

Creating a RaspberryPi DriveWire server

  • 2016/05/12  This is a work-in-progress article I originally wrote on February 8, 2015, but never completed. The other night I was trying to look up my notes to help Curtis B. with a NitrOS-9 boot disk and I realized I never completed this. I will try to finish it when I have a moment.


To get DriveWire 4 server running on a Raspberry Pi, you will do the following:

  1. Download the DriveWire server to the Pi and unzip it:
  2. Edit the config.xml file to default to your serial port on your Pi in <deviceType> and <serialDevice>. (i.e., “serial” and “/dev/ttyUSB0“)
  3. Run the server with no user interface:
    java -jar DW4UI.jar -noui
  4. On the CoCo, load the needed DriveWire modules from NITROS9/6x08L2/MODULES/RBF:, rbdw.dr, x0.dd up to x3.dd
  5. Use the “dw” command to test things by creating a blank disk image:
    dw disk create 0 /home/pi/test.dsk
    format /x0
    dir /x0
  6. Customize your boot disk to include the modules you want and read the documentation to learn how to use all the cool virtual terminals, MIDI and other neat features.

And now, the long version…

Materials Needed

  1. Raspberry Pi B (or B+, or probably the Pi 2 B). I did all these steps on a B.
  2. USB keyboard (a mouse makes things easier, but I do not have one so all of these tips will just use a Pi, keyboard and HDMI TV/monitor).
  3. Compatible* 8GB SD card (or larger).
  4. Ethernet cable to hook the Pi to the Internet. (Required if you plan to do the network install of NOOBS LITE).
  5. WiFi (with a supported USB dongle) or Ethernet is needed later for downloading the DriveWire software and updates, but there are ways to do all of this without any Internet access if you start with the full NOOBs installer.
  6. Compatible* USB serial adapter (or TTL->RS232 converter for use with the built in UART pins of the Pi).

Preparation on Windows/Mac/Linux

  1. Download the “NOOBS” installation for Raspberry Pi (currently 1.3.12). You can get the full NOOBS (780MB, just unzip and copy to the SD card and boot), or the NOOBS LITE (22.8MB) version.
    • NOOBS LITE can also be used. It is a much smaller download, but requires the Pi to be hooked up to the internet via Ethernet to download the rest of the OS files which is about 2355MB.
  2. Unzip the files, then copy them over to a freshly formatted SD card.

Preparation on the Raspberry Pi

  1. Boot the Pi using this card. You will see a menu of operating systems you can install. Choose “Raspbian [RECOMMENDED]” at the top by using the arrow keys and SPACE to select. You may also wish to hit “l” for Language and set it to “English (US)” or your preference, and “9” for Keyboard and select yours. Once Raspbian is selected, press “I” for install. It will ask if you are sure you wish to overwrite the SD card. Select “Y” for yes.
    • NOOBS LITE: The Pi will then download the Raspbian image (2.3GB), then install.
    • NOOBS: The Pi will then install.
  2. The Pi will (eventually) reboot and after a bit, you get a DOS-like screen for the raspi-config utility. Arrow over to Finish and press ENTER. You will not be at the Pi shell prompt.
    pi@raspberrypi ~ $
  3. At this point, I like to do a full reboot to make sure everything is working properly:
    sudo reboot
  4. On a reboot, you won’t go directly to a shell prompt. You will get a login prompt. The default account is:
    username: pi
    password: rasbperry.
    Log in and you will get back to the shell prompt. You will be in the home directory for user “pi”.
  5. Now we need to download the DriveWire 4 software. Note the filename will change when DriveWire is updated, so check the official site if this does not work.
  6. After the zip file is download, you can extract it by typing:
  7. DriveWire 4 is set up to run with a nice GUI with mouse control. This requires a keyboard and mouse, and the Pi to be set up with X-Windows running. Since I do not have a mouse, and plan to run the Pi headless with nothing hooked up to it but power and the CoCo, this is not an option for me. Instead, I need to manually edit the configuration file to tell it what Linux serial port I will be using.
    cd DriveWire4_4.3.3
    copy config.xml (always keep a backup!)
    pico config.xml

    The editor will open, and you want to look for a few entries:<instance category=”instance” desc=”Autocreated 2013-03-24 23:57:53.831″ name=”TCP connection via TCP“>

    <DeviceType category=”device” list=”serial,tcp-server,tcp-client,dummy” type=”list”>tcp-server</DeviceType>

    <SerialDevice category=”device” type=”serialdev”>COM14</SerialDevice>The first entry is just the name of the connection. You could change that to “Serial Connection” or whatever. The second “tcp-“server” should be changed to “serial”, and the “COM14” entry should be changed to your serial port device. On my Pi, when I plug in a single USB RS232 adapter, it shows up as /dev/ttyUSB0 so that is what I use.
  8. Save your changes back to the file (Ctrl-X, Y) and now you are ready to run the server without a user interface. (Getting the user interface to run requires installed two more additional packages, and I will make a tutorial for that soon, if anyone wants me to.)
    java -jar DW4UI.jar -noui
  9. After a bit, Java will load and the DriveWire 4 server will start. Java is big, and the Pi is small, so it can be quite sluggish. Now, with the USB cable connected between the Pi and the CoCo, you can start testing.

Preparation on NitrOS-9

This tutorial is being written for someone who already has an active NitrOS-9 system and wants to add DriveWire support to it. If you have no customized

If you are using one of the default NitrOS-9 disk images for you system, it should have a NITROS9 directory, and inside of it will be various device drivers and descriptors, including the ones used by DriveWire. Ultimately, you would want to make a custom boot disk that includes these modules, but here is a simple way to merge them together and just load them when you want to use them. From OS-9:

  1. If you are running a stock CoCo 3 with the standard 6809 processor, go here:
    cd /dd/NITROS9/6809L2/MODULES

    …and if you have upgraded your CPU with a Hitachi 6309, go here:
    cd /dd/NITROS9/6309L2/MODULES
  2. The modules you want depend on what you plan to do. Here is the list:
    • – this module handles all communication with the DriveWire server.
    • rbdw.dr – RBF device driver that uses DriveWire for disk access instead of disk hardware
      • ddx0.dd, x0.dd, x1.dd, x2.dd, x3.dd – device descriptors for the DriveWire disk drives (/x0 to /x3, with ddx0.dd being a /dd descriptor for DriveWire).
    • scdwp.dr – printer driver
      • p_scdwp.dd – device descriptor /p for scdwp.dr
    • scdwv.dr – virtual serial port driver
      • n_scdwv.dd, n1_scdwv.dd to n13_scdwv.dd – serial port descriptors. /n is the “next available” descriptor, similar to /w for windows. /n devices may also be used for MIDI.
      • midi_scdwv.dd – this is n14 but named /midi for MIDI programs that are hard coded to look for that name.
      • term_z_scdwv.dt, z1_scdwv.dd to z7_scdwv.dd – (??? not in the doc wiki)
  3. For my example, I am only concerned about the disk drives, so I would merge the following modules together:
    chd RBF
    merge rbdw.dr x0.dd x1.dd x2.dd x3.dd >/dd/dw
    This gives me a single file called “dw” I can load to get DW support instantly. First, I need to set the attributes to allow that:
    attr /dd/dw e
    …then I can just load it when I want to use DriveWire:
    load /dd/dw
  4. If this worked, you should now be able to use the DriveWire command, “dw”, to communicate with the server. Type “dw” and it should report back a list of commands:
    config  disk  log  midi  net  port  server
    …and you can then type “dw config” or “dw disk” to see what all it can do.

Using DriveWire

Here is an example of creating an empty disk image and formatting it:

dw create 0 /home/pi/test.dsk
format /x0
dir /x0

If you look on the Pi, you will see a new file “test.dsk” there. You can now use this disk like any other OS-9 disk. In my test, I copied my NITROS9 directory over to it just for fun:

chd /dd/NITROS9
dsave /x0 ! shell

DriveWire’s performance is not as good as you’d get from a No Halt floppy controller like the Disto Super Controller 2 or a hard drive interface like the Cloud-9 SuperIDE or KenTon SCSI. As disk activity is going on, interrupts are masked while data is blasted out of the bitbanger port. Still, it did a remarkable job keeping up with my typing. Quite impressive for a cheap cable and a $35 computer with a serial port.


  1. Make the DriveWire 4 server auto-start.
  2. Update the DriveWire 4 software from the command line (is this even possible?).
  3. Update the Raspberry Pi software.


One issue I immediately ran in to was a bunch of ERROR #207 (Memory Full) errors. mfree still showed 352K free, and it wasn’t the #237 (RAM Full) that happens when there isn’t enough room left in the main 64K memory map.

Building NitrOS-9 on Mac OS X

Since I have to relearn all the steps, I thought I would post them as I go through them. The NitrOS-9 website has a tutorial on building it, but here are my steps with some specifically for Mac OS X:

  1. Install the Command Line Tools for Mac OS X.
    We need the command line versions of the Mac OS X compiler so we can build the tools that are then used to build NitrOS-9. If you have XCODE installed, you may already have them. An easy way to do this is from a Terminal prompt:

    xcode-select --install

    That will launch the Apple Mac App Store installer and get the tools for you. Cool.

    Installing the Mac OS X command line tools.

    Installing the Mac OS X command line tools.

  2. Download Mercurial.
    The NitrOS-9 repository uses Mercurial as version control. You will need to download Mercurial. I had 3.2 the last time I did this, and currently it looks like 3.8 is available. There are several ways to download it using various package managers (Fink, MacPorts, etc.) but I don’t have this installed so I am just using the standalone installer:
    Depending on your Mac OS X security settings, it may complain that this is from an unknown developer and refuse to run. If you get this message, go in to your System Preferences “Security & Privacy” control panel and tell it to allow the installer to run:
    Screenshot 2016-05-01 17.26.21(Strange. The last time I did this, “Open Anyway” would let me bypass the security settings I am using. This time, it refused, and I had to temporarily allow “Anywhere.” Not sure what’s up with that.) After the install, you will have the “hg” command available.
  3. Download LWTools. These are the cross-compiler tools used to build 6809 source code from Mac/Windows/Linux systems. From a Terminal prompt, find a directory you want to download the lwtools to. I chose a poor location — “CoCo” inside my Downloads folder:
    alsmbpro:lwtools allenh$ pwd

    From this directory, use the “hg” command to obtain and build the tools. It will build the directory you specify from the command line (“lwtools”):

    hg clone lwtools
    cd lwtools
    sudo make install
    cd ..
  4. Build Toolshed.
    Next we want to build Toolshed. This is a series of command-line utilities that operate on CoCo/OS-9 disk images (like those used with emulators and the CoCoSDC interface). Once again, I do these steps from my “Downloads/CoCo” directory:

    hg clone toolshed
    cd toolshed
    sudo make -C build/unix install
    cd ..

    (Note: I had to use “sudo make…” here to get it to build on my system.) The different build/make process shows the different styles of the various developers that made these tools. (Note: Mine seems to fail looking for a command “markdown” at the very end. Not sure what this is, but it seems to be building HTML documentation or something.)

  5. Build NitrOS-9.
    Now we are ready to download and build NitrOS-9. Once again, I start in my “Downloads/CoCo” directory, and issue the following hg commands to download all the NitrOS-9 stuff:

    hg clone nitros9
    cd nitros9
    make dsk
    This will build absolutely everything, including tons of ports and disk images you likely do not want. (i.e., if you are only interested in a CoCo 3 6809 setup, why build all the CoCo 1/2 and Dragon versions, or any of the 6309 stuff?). I always build everything, but you can also specify to build just a specific port. For my CoCo 3/6309 build, I could do this instead:
    make dsk PORTS=coco3_6309

    After this, you will have all the sources, and have built all (or some) of the sample disk images for various types of hardware (CoCo 1/2, CoCo 3, 6809 or 6309, CoCoSDC controller versus floppy or IDE hard drive, etc.).

  6. Updating NitrOS-9 and the Tools.
    Later, if you want to update your sources, you can use this comment from the “nitros9” directory:

    hg pull
    hg update
    make dsk

    I do this occasionally to get the “latest and greatest.” You can do this for the other tools, too, by changing in to their directory then issuing the “pull” and “update”, then the appropriate make command.
    If you get a merge conflict because you changed something locally, you might see this:

    alsmbpro:nitros9 allenh$ hg update
    abort: outstanding merge conflicts

    You can use this command to see what files have been changed on your local repository that conflict with the master files. This happens if, for instance, you tweak a makefile or build list or source code:

    alsmbpro:nitros9 allenh$ hg resolve -l
    U 3rdparty/utils/tlindner/sdir.asm

    This reminded me that I already Tim’s “sdir” source code (for CoCoSDC) so enable built in help and such. I have to revert those changes if I want to update, or learn how to use the merge too… I forgot!

These steps should get you everything you need to begin playing with NitrOS-9 on a real CoCo with the CoCoSDC interface, or an emulator. If you plan to use real floppies, you can use toolshed utilities to format and then copy disk image .DSK files over to the physical floppy, but I don’t have any way to hook a 360K Floppy drive to my Mac so I have never done this. CoCoSDC is the way to go there ($40!).

More to come…