User avatar
Seattle, WA, USA

Posted Tue Dec 04, 2018 9:51 am

Earlier in October I lucked into a gorgeous Commodore C128DCR, one of the best looking 8-bit machines Commodore ever made.

What I didn't realize at first was that the internal floppy drive was on the way out. I would read disks on occasion, but it couldn't write. Then it started to actually eat disks. Sometimes it would let them eject (the spindle wasn't fully releasing) making for some stomach churning moments while trying to remove disks. In another heart breaking moment it actually scored the an original disk's surface, quickly turning the thing into landfill filler.

I cleaned the drive's heads and lubed the rails. Didn't make a difference. I also learned about an excellent program every Commodore 8-bit owner should pull down and put in their arsenal called the 1541 Diagnostic Cart by Jani at

The file is in CRT format, so if you have an Ultimate cartridge (or the ability to program your own cartridges) you can pop this in and do all kinds of very handy diagnostic tests on disk drives. Using this program I never once got my 128D's internal drive to pass a performance test. It would bomb out early on never getting beyond track 11.

It was at that moment I knew the internal drive needed to go. It was well beyond my ability to repair it. And while I read that about ten thousand NOS 1571 head replacements made their way onto the scene a few years ago, I've not seen any crop up anywhere today

So I began to ask around, "Could I take an external 1571 floppy drive and put it in a C128D?"

Some members of various forums claimed to have done such a thing. The sysop of ParticlesBBS said he'd done it twice. But there was not a single site I could find with any solid info. I did hear some valid concerns, based on pictures online, that the external 1571 drive had shorter connecting wires than the internal drive. I figured I had no choice, and if that meant I had to wire up 20 little extensions, I really had no choice.

I acquired a nice looking and functional external drive off Ebay and got to work.
Next I removed the plastic top shell, and then removed the screws that held the mechanical drive from the bottom case. I left the little motherboard and PSU in the bottom shell.
The wires on the internal 1571 do indeed look short. But they are also twisted together to reduce any slack.

If you untwist the three main wire bundles from themselves, you gain a few millimeters back.

I then took off the 128D's case to compare. The 128D's wires are indeed a few centimeters longer, and the drive itself sits higher up than the external version. Other than the wiring, however, these two drives look nearly identical. There was only one real difference - the internal drive had a mounting bracket on the bottom of it that would require removal.
Internal drive on the C128D close-up: The internal drive does have slightly longer wiring than an external 1571 drive.

However, even though the external drive's wires are shorter, this is exaggerated because Commodore used tiny little wiring ties to remove any slack. I quickly used some snips and removed these little bundling ties. This gave me some precious and much needed length back.
External Drive close-up: Many of the wiring bundles were made to appear shorter than they really were. Removing these little ties helped a lot.

After removing the external drive from its housing, I needed to remove a bottom bracket that is not used in the C128D.
This can be put into storage once it is removed as it won't be needed for the C128D.

I took a quick note of the manufacturer of the drive I'd just taken apart for organ transplanting.

Finally it was time to remove the C128's internal drive. This machine is so easy to work on. Once you get the case off, the only two things inside besides the motherboard are the floppy drive and power supply. That's pretty much it. You can see in my pics some heat sinks I'd previously added to some of my chips. Now that the drive was coming off, I'd be able to add a few more to the chips below it.

Three screws and the floppy drive comes out. It's practically levitating.
You slide the drive towards the rear of the case and it just lifts out.

Now I could add a few more heat sinks since I was already this far.

One little gotcha that happened to me. When you either take off the case of the C128D, or remove the mechanism from a 1571 drive, you have to first remove the plastic lever used for closing the disk bay. There are no screws or latches - it just pulls straight out. However, on my external 1571 when I removed the lever the internal rod it plugs into fell out. It took me a few minutes of finagling to put it back together before installing it into the C128D. Out of everything I had to do, this annoyance (which was my fault) was the most difficult task of the entire job.
After putting the new drive into the 128D and re-fastening the 3 mounting screws, I attached the wiring. Everything reached! There was one bundle - the smallest connector closest to the front of the case - that had a lot of tension on it, though. It reached, but it was tight.
The small wiring connector seen here on the far right (with the black, brown and orange wires) made the connection but just barely.

I noticed that the wires were all fed through a pill-shaped hole in the drive's housing. That's when I had an idea.
I detached the small 3-wire connector and backed it through that hole. Then I reattached it to the connector on the motherboard by feeding the wires underneath the drive. The wires weren't being pulled tight anymore. It was perfect!
Note that the tension on the wires on the right is now gone.

In fact, I now had more than enough room with plenty to spare.
At that stage I buttoned everything back up again and gave the drive a test spin. Within minutes I was playing Hitchhiker's Guide to the Galaxy again - in 80 columns - and successfully saved my progress to a blank using the new drive once I made it to the Vogon ship. Success!

So is the 1541 external floppy drive a drop-in replacement for the Commodore 128D? Yes, yes it is.

User avatar

Posted Tue Dec 04, 2018 2:30 pm

Wasn't there something about flippy disks that the 15_4_1 can't do?

User avatar
Springfield, MO

Posted Tue Dec 04, 2018 2:31 pm

Nice work, Eric! Now kindly send me that 1571 spare you've got so I can fix it. ;)

On a more serious note, how did you manage to put so many images on a single post?

User avatar
New Orleans, LA, USA

Posted Tue Dec 04, 2018 2:53 pm

Nice work documenting things, Eric.

User avatar
Seattle, WA, USA

Posted Tue Dec 04, 2018 3:06 pm

@McTrinsic, not sure I understand your question. But the main difference the 1571 has from all of its brothers is that it has 2 heads. So it can read/write a floppy disk on both sides without flipping the disk over. The 1541 and 1541-II have a single head and require flipping disks for larger programs.

@EZdineG, I'm an Admin. I don't have limits. Bwahahah! Seriously though, I wasn't fully aware you did. I can bump posts up for other folks to have more images no prob. That being said I compress my images. I constrain them to 800x600 and make them 60% quality, lossy JPGs since 35% of our audience is on Mobile. So if folks want to post a ton of pics I'm all for it. Just try not to upload RAW 4000x3000 full-res images, or the site could start to chug and mobile folks would eat some data. I had a guy on another site complain about that here once when things first got started.

@obitus1990 Thanks! I was so happy/proud it all worked out and was pretty painless.

User avatar
Seattle, WA, USA

Posted Tue Dec 04, 2018 3:14 pm

@EZdineG there appears to be a limit on attachments (set to 3). But I attach these images then make them inline images. The UI is a little janky, but making your images inline content makes the software not see them as attachments to a post (I think).

For now, regardless, I've updated the attachment quota from 3 to 20, whatever that means.

User avatar
Lexington VA

Posted Tue Dec 04, 2018 3:39 pm

Nice. I have several NOS original 128DCR internal PSU if you ever need a new one. I have like 10 or something. dont ask why lol!

User avatar
Seattle, WA, USA

Posted Tue Dec 04, 2018 3:56 pm

@BloodyCactus Holy.......****! I might pick one off you at some stage as I'm a nut about having redundant systems in place.

User avatar

Posted Thu Dec 06, 2018 1:56 pm

Right, flippy disk means you don't have to flip it... picked up the term in context of the Kryoflux where you can only dump certain double sided disks if the drive supports it. Must be a 'flippy' drive.

Anyway all I am saying is you lose some compatibility with the 1541 in it. The 1571 could utilize both sides at the same time afair. So it wouldn't help if you could turn the disk for some programs.

User avatar

Posted Sun Dec 09, 2018 8:00 am

B sides of disks written with a 1571 can't be read by a 1541 because, naturally, the 1571's direction of writing is opposite to when flipping the disk (the motor only turns in one direction). Likewise, the 1571 can't read B sides of disks written with a 1541, unless it is also flipped in the 1571.

Return to “8 Bits”