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Home | Getting Started | Connecting | Running the Examples | Toolchain Installation | Building the Software | Installing the Emulator | Debugging with MAME | Using SD Cards

Connecting your rosco_m68k

Once you've built your new old computer, it's time to start talking to it!

Hooking up your rosco_m68k to your regular modern computer is a simple affair, thanks to the wonders of modern technology. USB to Serial (UART) converters are cheap and plentiful, and you might even have received one along with your kit (if you opted for one when you purchased). Let's look at what you'll need to get started.

You'll need:

  • A USB lead with +5V and GND broken out to Dupont® connectors, or alternative power connector
  • A USB to Serial converter (sometimes called an FTDI converter) or cable
  • A USB Mini-B to A cable

Warning!

  • Incorrectly connecting your rosco_m68k may damage it and other equipment connected to it - Check before you connect!
  • Connecting your rosco_m68k to a power source with a voltage higher than 5V is likely to damage it - Check before you connect!
  • Your USB to Serial converter must be 5V tolerant. Some have a jumper to select either 5V or 3.3V, ensure this is set to 5V - Check before you connect!

Connecting the Power

You'll need some kind of 5V power supply that can connect to the two-pin power header on the rosco_m68k. We use modified USB cables and regular wall-wart adapters for this, but any well-regulated 5V power source will work just fine.

If you don't have a power lead, it's easy to make one from an old USB lead - check out this video, for example.

When connecting the power, be sure to observe the polarity - the pins are clearly marked on the board as 5VDC and GND. If using a USB cable, these should be connected to the red and black wires, respectively. It's really important to connect these correctly, getting them the wrong way round will damage your rosco_m68k! If in doubt, use a multimeter to check the polarity before you connect.

Connecting the UART to the USB to Serial Converter

The exact method for doing this will vary depending on the specific converter you have, but the general principle remains the same.

Find the four-pin UART connector on your rosco_m68k - it's on the right side of the board, and the pins are marked CTS, RXD, TXD and GND.

Now, on your USB to Serial converter, find the corresponding four pins. Most converters (including the one we optionally supply) will already have headers soldered on for these pins.

Using a four-way wire with DuPont connectors at each end, make the following connections:

rosco_m68k USB to Serial Converter
CTS CTS
RXD TXD (Sometimes TX)
TXD RXD (Sometimes RX)
GND GND

Now connect the USB cable from your USB to Serial converter to your computer. The converter will probably have some LEDs that light up at this point, and your computer should recognise it as a new serial device.

The new device should appear in the /dev directory, ready for use. On macOS, for example, it's named /dev/cu.usbserial-XXXX. You can find it easily by running:

ls /dev/cu*

On Linux, you can find the name of the device by looking at the output of the dmesg command.

Connecting an SD Card

If you're running Firmware v1.3 and up, you can connect an SD card using an Arduino SD card adapter. Depending on your board revision, this either connects to a dedicated header (on 1.23 boards and higher) or to J5 (on 1.2 boards and below).

See this page for a detailed hookup guide, as well as information on supported cards and formatting.

Installing Software and Testing

Note: These instructions apply to macOS® and Linux only. We recommend that Windows® users use a Linux VM.

If you hit compilation failures or other issues with CKermit, you may need to install from source - we maintain a fork of the 9.0.160 version, slightly modified to compile on modern systems: rosco-m68k/ckermit.

In this section we'll install two programs, minicom and ckermit. If you already have them installed, or have another terminal emulator / kermit client that you like, then feel free to skip this section.

We recommend using Homebrew to manage your software. If you don't already have it, you can find simple installation instructions at brew.sh.

If you're using Linux and don't want to install Homebrew, it's very likely that both these packages are available from your distribution's standard package repositories - you'll be able to install them with apt-get, yum, dnf, or whatever your regular package manager is called.

To install the two packages with Homebrew:

brew install minicom c-kermit

(Note: If using your Linux distribution's package manager, the Kermit package is likely to be called ckermit instead of c-kermit.)

After installation, both packages should be ready to use, but we need to add a little bit of configuration first.

Create a new file in your home directory called .kermrc, or edit the existing one if it already exists. The contents of this file should be:

set carrier-watch off ;
set flow xon/xoff ;
robust

Now launch minicom:

minicom -D /dev/cu.usbserial-XXXX -c on -R utf-8

Replace /dev/cu.usbserial-XXXX with the path to the device you determined in the previous step. On Linux, this will probably start with /dev/tty... rather than /dev/cu....

Note: On Mac, you may find that the Esc+KEY combination used in the following section doesn't work. If you're using iTerm2 you can emulate this combination with the right option key by opening the Profiles menu, selecting Open Profiles. Click the Edit Profiles button, and with the Default profile selected in the left pane go to the Keys tab in the right pane. Near the bottom of this is an option to change the mapping of the Right Option key - change this to be Esc+.

Once Minicom has launched, open the options (Esc+O or CTRL-A, O on Linux) and navigate to Serial Port Setup. Edit the options as needed, then escape out and select "Save setup as dfl". Restart minicom to ensure the configuration is loaded.

Power up your rosco_m68k (or hit the reset button if it's already powered up), and you should see the startup message on-screen. Congratulations - you're now all set, and your rosco_m68k can talk to your computer!

From here, you can use Esc+S (Ctrl-A, S on Linux) to initiate a Kermit file transfer, and send a compiled binary program to your board and interact with it in the serial terminal.

Now that the rosco_m68k is successfully talking to your computer, it's time to run some example programs! We'll do that in the next section.

Home | Getting Started | Connecting | Running the Examples | Toolchain Installation | Building the Software | Installing the Emulator | Debugging with MAME | Using SD Cards

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