Amiga External Floppy controller

This project was initially made for the purpose of using an internal Amiga floppy as a secondary drive for copying disks. But later, I added jumpers so that PC floppies can be used too, since these are easy to find. I later also found it useful to have a jumper selector for selecting DF1:, DF2: and DF3:


It turns out that the DB-23 connector that goes in one end of this adapter has gone out of production several years ago. There are still connectors available, but at a price that is not realistic and it smells like speculation. After experimenting a bit, I found that using a regular DB-25 connector work just as good. These are still in production, and to my surprise they work great. Better than great. All you have to do is to snip off the extra pins with a sidecutter.

I was afraid they would be awkward to fit, and easy to put in wrong, but instead they slip right on without any issue everytime. At this point Im convinced its a real waste of money to buy DB-23s when the DB-25 work so great. I have actually made a couple of these to people insisting to have the correct connector, but I had to up the price considerably to recoup the extra cost.


The PCB was made in a way that you can eighter solder in a floppy connector, or just use pin headers like in the first picture. The Floppy connector would ensure that it is not possible to put the cable the wrong way around. Look at the image for default setting when used with a Amiga floppy drive or a Gotek with hacked firmware.

Jumper settings:


Old version.

This is the latest version PCB I made. I added a Ready jumper so that PC floppies without ready (rdy) jumper can be used too.

DS0/DS1 jumper.
The jumper to the left in the picture is drive select. I made this because many PC floppies has no jumper for drive select. (DS0 or DS1) on a PC, floppies was usually hardwire as DS1, and then they used a twist in the end of the IDC cable to swap the pins back to DS0 for the computer to read it as A: if you connected a second floppy drive to the IDC cable, there was no twist on the connector and the computer would read it with the hardwired setting DS1, and assign it as B: You can safely try both.

Amiga/PC jumper
The Amiga/PC jumper is to tell the adapter if you connected a PC compatible floppy, or a Amiga floppy. Its what forces a PC floppy to be compatible with your Amiga. Default would be Amiga. Set to PC for PC floppy.

Ready jumper (New on later revisions)
The Ready jumper is to tell the adapter if you connected a PC compatible floppy, or a Amiga floppy. Its what forces a PC floppy to be compatible with your Amiga by forcing the ready setting to match the Amiga requirement. Default would be Amiga. Set to PC for PC floppy.

DF1 to DF3 jumper
The last one, is the jumper set that has 6 pins. It selects between DF1:, DF2: and DF3:. Default would be DF1. I made this because sometimes you have already 2 floppies connected. My Amiga 2000 had 2 floppies inside, so to use this external adapter on that machine, I had to be able to wire this as DF2: to avoid problems. DF3: is when you have 3 connected drives and this is number 4.

Fortunately, this adapter works great with the Gotek, which is one of the most popular addon in Amigas these days, due to its availability, and that it is so easy to use.

The old floppydisks are getting harder to find, and the drives are getting old and worn out. My personal preference is to have both. I still like to have original disks, but having the .adf files on a SD-card is so convenient and tidy.


C1 100nF Decoupling Capacitor
C2 100nF Decoupling Capacitor
DB-25 Connector to be modified to DB-23
IDC FDD Connector
4X Jumpers
R1 2.2k resistor
R2 2.2k resistor
R3 2.2k resistor
U1 74LS74N DIL14
U2 74LS38N DIL14
Power Cable with connector to Floppy drive


This project with PCB and parts can be purchased on ebay:
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PS/2 to Amiga/Atari adapter

I really wanted a PS/2 to Amiga adapter, so I ended up making this PCB in Eagle CAD based on information freely available on the Internet. I ended up making one that can use both USB and PS/2 connector, and the option to change between Amiga and Atari ST mode with jumpers. It also works on Commodore 64 in certain applications.


This thing work on a lot of USB mouses, but not all. It requires the mouse have the PS/2 protocol to work. A lot of mouses with PS/2 plug also included a PS/2 to USB adapter. Thats a good indicator to see if it works.


This is plug and play. No need to install drivers.



It does fit the Atari too. I had to make it super slim, because of the way they designed the case.

This is how I assemble these.


From the left, you can see I start with the Microchip. Then I move on to solder the DB-9 connector. Third, I do the capacitor, then the jumper pins. Lastly, I decide wether to install a USB or PS/2 socket. I do it like this because it is easier to install the smallest components first, moving over to the bigger last.

The modes:


This image shows the two different modes. To the Left its set to Amiga mode, and to the right its set to Atari mode.

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CDTV Joyport Adapter

After finally getting hold of a Commodore CDTV, first thing I noticed was that it did not have the usual DB-9 connectors that the other Commodore models have. The machine did have a mouse port, but it turns out it is not a standard one, and I did not get one with the machine, so I had to find another solution for using mouse and joystick, because the remote controller was a weak subtitute for a real joystick and mouse in my opinion. I also wanted to use a modern optical mouse together with my already made PS/2 to Amiga adapter.

Looking at the CDTV service manual, at page 17 there is a chip marked 252609-02 at location U75. Turns out it has all the pins for both the joystick port and mouse port. My first plan was to solder wires directly from the chip and onto 9-pin connectors with solder cups. But then I decided to draw a PCB in Eagle CAD instead.


I opened my CDTV and it turns out there are a few components blocking a big PCB, plus that the distance between the mainboard and the lid is quite narrow. So I had to make the size and placement of the connector as shown above. The idea was to use the same principle they use when they make adapters for EEPROM programmers. There is a socket for the original chip, and then there is legs on the underside to insert into the socket on the motherboard. Now we can just route some traces from the pins on the chip that has the needed signals for left, right, up, down, fire and ground without soldering on the chip itself.

I found out that on Ebay they still had IDC DB9 connectors that was perfect for his project. Turns out 20 pins IDC sockets were much cheaper than 18 pin, so I decided to design the board for a 20 pin connector, but to only connect 18 pins (2pcs 9pin connectors) So the board consist of these parts:

1PCB, 1pcs 20pin IDC, 2pcs IDC d-sub 9 pin male, Turned pin header for inserting into the U75 socket, 1pc 40pin DIP socket for the 252609-02 chip, Double 2.54mm header for the 20pin IDC, 45-50cm IDC cable.

It turned out that the distance between the lid and the PCB was so narrow, that I had to use angled pin headers for the 20pin IDC connector. Below, in the picture to the right, you can see that the connector take a lot of room, so I had to desolder the pin header and replace it with one with angled pins as shown on the left picture.


Because the CDTV remote uses the pins from Joystick port 1, there might be a problem using both at the same time with a mouse or joystick. The solution is to try and press RIGHT on the CDTV remote once the CDTV is switched on with your program or game loaded. If this wont work, you can disable the CDTV remote like this: remove U75, bend up pins 6, 7, 8, and 9, and replace it back in the adaptor’s socket. I might make a jumper or DIP switch solution on my next revision of the PCB, so that those pins can be disabled without disturbing the chip. They will fit perfectly on the side of the 20 pin IDC connector. If you look closely on the picture, you will se that the pins are bent to the side. I dont recommend anyone to bend them several times. A different approach to solve this would be to cut the traces on the adapter instead, to avoid bending the pins. The traces to cut would be the ones leading from the socket on top of the adapter that lead out from the 4 pins I bent in the picture.


This project with PCB and parts can be purchased on ebay:
or from