Modifying a PC floppy drive to work inside an Amiga 500

My Amiga 500 Plus no longer has an internal floppy drive. It was given away months ago to help another Amiga user. I needed to replace it, and I realised that I’m completely out of Amiga floppy drives. So, I decided to see if I could convert a PC one to fit. Here is the story.

The Drive

I have a spare Citizen Z1DE-57Aa drive that was completely missing a fascia. In fact, I used it in an earlier blog post attached to a Greaseweazle to backup a copy-protected disk.

Circuit Modification

Amiga floppy drives use the Shugart standard, PC floppy drives use something a little different, they also use a different ID on the cable. So, the drives need a little modification. A description of the changes needed can be found in an earlier blog post. I didn’t know the exact changes that needed to be made to this drive, I could have buzzed around and figured it out, but luckily, someone had already documented it. I made the changes specified, and the end result looked like this.

Physical Modification

There are a couple of initial problems we need to solve to make it fit, the first is that the drive is slimmer than an Amiga floppy drive. I happen to know (don’t ask me why, I can’t remember) that to make PC floppy drives the same height, you need to raise them by 6mm. I therefore screwed some 6mm standoffs to the bottom of the drive and used the original Amiga standoffs for the back two screwed into that.

Next up is the eject button, the Amiga eject button needs to be in a specific place to fit out of the computer, it is a different place to the location of the drive. After six attempts with minor design tweaking each time, I managed to print something that fitted perfectly. The top is my print, the bottom is the original button.

I could have printed using a colour-matched PLA to the Amiga, but I actually quite like the contrasting black.

Fit Testing

Now that the drive has been sufficiently modified, it is time to test everything. The drive fitted fine in place and the eject was nice and smooth.

Once I popped the lid on the Amiga, things weren’t quite so smooth, the lid of the floppy drive overhangs the face, which meant that the lid of the Amiga wouldn’t fit. I solved this by pulling the lid of the floppy drive back slightly.

The next problem is that disks would get stuck during eject. They would get wedged between the drive door and the casing of the Amiga. This was easy to resolve by simply removing the drive door. This might be why Amiga 500 drives never had one.

The Result

This is the final fit with the disk in. I could maybe clean up the eject button a little, but it does have a nice feel to it, and is functional.

Does it work? Let’s put in a disk-read intensive game, Lemmings.

I’m going to call that a win!