OpenAmigaFourPlayerAdapter is an Open Hardware adapter that allows connecting two additional joysticks to Amiga Computers, bringing the total to four.
Some Amiga Games support more than the two joysticks you can connect directly to all Amiga models. The two extra joysticks are supposed to be connected to the parallel port through an adapter. OpenAmigaFourPlayerAdapter is an Open Hardware implementation of such an adapter, based on Tomi Engdahl's Multi-joystick extender circuit, which claims to be the de-facto standard for this. The same circuit was found on other sources, so this should not be too far away from the actual truth.
The adapter slightly improves that design by also providing 5V power to the joystick ports. Finally, its apparently odd shape allows it not to bump into the nearby power/audio cables that will be connected to your Amiga.
Testing was only carried out with DynaBlaster. Here is a list of more games that should hopefully work with it. Actually the list includes the same circuit the adapter is based on, so there are good chances this will be the case. Please report any failures.
Building the adapter is very easy, just note that you need all male connectors, for both the DB-9 and the DB-25 ports.
The adapter needs no configuration. The only option is whether the 5V power pins of the joystick ports should actually be powered or not. The adapter itself is fully passive and consumes no current. Most old-style joysticks do not need power either, but if you are using one with autofire functionalities or maybe some "complex" adapter, it probably will. Now, the problem is that parallel ports are only required to supply a current of 10 mA, which is very little and probably not enough for even the simplest controller that needs power.
Luckily, most (if not all) Amiga models actually go beyond that and are able to provide about 100 mA. I really recommend you to check personally what is inside your Amiga: there should be a current-limiting resistor connected to pin 14 of the parallel port (It should be labeled E501 on the A500): I found out that this is usually 47 ohm 1/2 W (I checked on an A500 rev 8A, an A600 rev 1.5 and an A1200 rev 1D.4). If this is your case as well, then you will be fine, but please make sure this applies to your Amiga, or you might blow that resistor! You have been warned, I take no responsibility!
Once you are sure your Amiga can bear the current, just close the jumper placed near the port(s) of interest.
Finally, please note that you are recommended to only connect/disconnect the adapter and the joysticks while your Amiga is powered off, in order to avoid any risk of damage.
If you want to get this board produced, you are recommended to get the latest release rather than the current git version, as the latter might be under development and is not guaranteed to be working.
Every release is accompanied by its Bill Of Materials (BOM) file and any relevant notes about it, which you are recommended to read carefully.
I am not providing ready-to-use gerber files. If all you want is to get boards made, I would really appreciate if you did so in a way that supports the project.
One 3D-printable enclosure is currently available for this board:
- Kindly contribution by Youen Chéné available in enclosure folder. It needs 2 screws for assembly.
The OpenAmigaFourPlayerAdapter documentation, including the design itself, is copyright © SukkoPera 2020.
OpenAmigaFourPlayerAdapter is Open Hardware licensed under the CERN OHL v. 1.2.
You may redistribute and modify this documentation under the terms of the CERN OHL v.1.2. This documentation is distributed as is and WITHOUT ANY EXPRESS OR IMPLIED WARRANTIES whatsoever with respect to its functionality, operability or use, including, without limitation, any implied warranties OF MERCHANTABILITY, SATISFACTORY QUALITY, FITNESS FOR A PARTICULAR PURPOSE or infringement. We expressly disclaim any liability whatsoever for any direct, indirect, consequential, incidental or special damages, including, without limitation, lost revenues, lost profits, losses resulting from business interruption or loss of data, regardless of the form of action or legal theory under which the liability may be asserted, even if advised of the possibility or likelihood of such damages.
A copy of the full license is included in file LICENSE.pdf, please refer to it for applicable conditions. In order to properly deal with its terms, please see file LICENSE_HOWTO.pdf.
The contact points for information about manufactured Products (see section 4.2) are listed in file PRODUCT.md.
Any modifications made by Licensees (see section 3.4.b) shall be recorded in file CHANGES.md.
The Documentation Location of the original project is https://github.com/SukkoPera/OpenAmigaFourPlayerAdapter/.
If you want to support the project, you can order the boards from PCBWay through this link:
You get my gratitude and cheap, good quality PCBs, professionally-made. I get some credit that will help with this and other projects. You won't even have to worry about the various PCB options, it's all pre-configured for you!
If you still have to register to that site, you can use this link to get some bonus initial credit (and yield me some more).
You can also buy me a coffee if you want:
If you need help or have any questions or suggestions, you can join #OpenRetroWorks on FreeNode through your favorite IRC client or the webchat, or the official Telegram group.
- Graham P. for sending me the design of a similar adapter he was working on.
- Tomi Engdahl for publishing the circuit.