One of the weirdest super powers of the CMD FD-4000 disk drive (which is being legally recreated in 2024 now) is its ability to somehow create ED Extra-high Density disks from HD High Density disks.
ED disks can hold a whopping 3.2MB, while HD disks can only hold 1.44 (PC) or 1.6 (CMD) MB.
Even stating such a thing can create a bit of debate in some circles for technically legitimate reasons. For example, a very intelligent engineering friend of mine said when hearing this:
And he sent a link to Wikipedia with a definition of perpendicular recording, which I'd actually read the previous day trying to understand the physical differences.HD disks won't work as ED disks. Different magnetization field strength and perpendicular recording instead of horizontal.
Frankly, the promises by CMD around this topic seemed hard to believe all things considered. And yet, this feature is extremely important especially in 2024 but even back in 1997 when these drives were being sold. Why? Because ED disks have never been in great supply, and in 2024 they are nearly impossible to find. You might find some through individuals you meet, but there are no stores where you can go find these things. Even back in the day, my understanding is most folks had to order ED disks via mail-order.
So the ability to format the extremely common HD disk into an ED disk is kind of important if you want to take full advantage of the FD-4000. Otherwise you may as well stick with the FD-2000 (which in my opinion is one of the single best pieces of hardware for our Commodore machines). Of course, the FD-4000 can do everything the 2000 can, but if you get the 4000 you need some disks for it that open up the 3.2MB promised land.
Something else worth pointing out to the skeptics: This process only works with an FD-4000 drive. If you convert an HD disk to ED format, you won't be able to run over to your NeXT machine and start using like a NOS ED disk. My understanding is that this conversion only works with FD-4000 drives. So perhaps that's part of the special sauce.
What about data stability over time? I asked the creator of the new drives, Thomas Christoph aka Corei64.
Christoph:
Thankfully a kind soul I recently met sold me 3 original ED disks, and gave me another when we met at this month's SEA-CCC meeting in Seattle. So I have more than enough disks now, but I wanted the insurance of having some HD disks converted as backups. It took me a down quite the rabbit-hole.I can believe that there is a difference between ED and HD disks in terms of the ability to retain data, but I have been doing this for years, and thus far, have not encountered data loss. Am I lucky? Perhaps. So far so good though.
The Process
Here's the fun part. The first thing you need to do with your HD disk is actually drill a hole into it on the left side below the original hole. You can do this quite easily using a handy 3D-printed guide Thomas includes with the drive when you purchase one. A 1/8" drill bit fits the hole perfectly.
Note: I've discovered that some disks are actually thicker than others and sometimes getting the guide onto the corner can require quite a bit of force. I've actually bent one disk completely in half trying to get the guid on. Other disks fit perfectly with no issues at all. Bottom line: not all disks are created equally. TIL
You then need to cover the HD hole with some sort of opaque tape. I've been using electrical tape. Presumably there is some sort of sensor (LED light?) we're trying to fool here.
- An Apple Newton disk for Windows? I did not shed a tear when I used the drill on this disk.
You also need to load the CMD software from their FD Utilities disk called FD Tools.
You can load this off a 1541 on 5.25" floppy or, in my case, from a 3.5" disk I had previously formatted and converted into a 1581 800k disk for my FD-2000. Thomas also includes the software in a partition on a disk he puts in the drive when he ships it to both protect the drive mechanism during transport as well as convenience for the customer. I already had one, though, and used my own disk in this case.
So, I'm reading FD-Tools on the FD2K set to ID8, and I have the FD4K set to ID10.
- One thing you notice really quickly with the new drives is the LEDs are about 5-10x brighter than the original drives from the 90s. A friend of mine who looked at it with me said I could add a resistor to dim it down. It's not overly annoying or anything but being a bit of a purist I might consider something like that later.
When we load FD Tools, it automatically sees my 2nd drive as the "work drive" which is really cool. It makes it the drive looking for disks to format and/or partition.
Once I put a disk in the drive I can pick a program to "Log" the disk. This basically does a quick Read and lets us know the size and format of the disk in the drive if it can identify it. For example, it might say I've put a common HD IBM PC 1.44 disk in the drive, or 720K, or whatever. It's actually quite handy if you have a stack of random PC disks and don't know their capacities (like me). What we want is HD PC 1.44.
Once you get a 1.44 HD disk in the drive you then need to format it using the first program in the list.
You change "CBM" to "CMD" with the tools provided, flip the capacity to 3.2MB and keep it in Native mode, give it a name and ID and start the process.
- CMD's software was so good. Make sure you're using version 1.05 of FD Tools, by the way.
If all goes well, in about a minute you'll have a 3.2MB capable disk. Afterwards you can then use a different program in FD Tools to partition the disk into however many partitions (or "disks") that you want. I'm leaving mine wide open for now as I plan to move all of my GEOS/Gateway files onto a single disk.
Your menu screen will update if you attempt to log the disk after the format is successful. Note the upper-right corner of the screen.
- This is after a successful conversation from HD to ED. Note how it doesn't called it an ED disk, but rather a CMD 3.2MB disk. Interesting, right?
The Problem
When I first tried to convert my HD disks to ED, it would consistently fail. Out of 6 attempts I only got one disk to format. That's a 16% success rate. Alarmed, I went to a channel on Discord run by Greg Nacu of C64OS fame where I knew several CMD fans and new owners of the FD4K reside.
Greg had attempted to format 4 HD disks and 3 of them worked perfectly. The 4th was garbage.
Another member who goes by the moniker "CommodoreSam" had tried stacks of disks and was unsuccessful 100% of the time. I zeroed in on his experiences because I felt I was closer to his than Greg's. He'd tried several different brands, drilled the holes, covered the other holes, taken the drive apart, etc.
Yet another member who had an original CMD FD4K drive who tried to help showed how in his case he had 100% success. He even shot a short video demonstrating how he could take an old AOL disk and never even drill a hole or cover the other! He quite literally just took a random PC disk unaltered in any way, popped it in his drive and proceeded to successfully format it to ED capacity right then and there. He'd been doing this for decades and has yet to have any issues at all. It seems to fly in the face of science and physics, but there you go.
Exasperated, CommodoreSam decided to use one of those weird disk drive head cleaner disks and ... somehow it seemed to work! After cleaning the heads on his "new" drive, it began to format all of his HD disks to ED.
Nervously hopeful, I pulled my own head cleaner out.
- It never would have occurred to me to clean the heads on these new drives, but it can't hurt.
After using the FD Tools to "read" this thing a few times, I waited 5 minutes for the fluid to dry and tried again.
This time, I tried 5 different disks and I got 2 of them to work. These were from the stack of failures from the day before. So now I'd moved from 16% success (1 out of 6) to 50% success (3 out of 6). While not at everyone else's level, this was good enough for me. I'll be using my original ED disks first and foremost, but I'm quite happy I'm able to convert some cheap and easy to find HD disks to 3.2MB.
Phew!
What all of this seems to imply, however, is that not every drive mechanism is created equally. I'd really like to source some from different manufacturers (like the guy who doesn't even have to alter his HD disks at all!) although I'm not exactly sure where to even look at the moment. That's another rabbit hole for another day, though.
After taking the drive apart to clean the heads, I noticed two pins were sticking up, one, I guess, for sensing HD and the other for ED. I put a little folded piece of paper in between the front and back of the HD hole to stiffen the tape. I'm three of three with success. Maybe this is common knowledge. I thought the tape was blocking a light sensor.
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