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Yellowstone Manufacturing is Go!

The i’s are dotted, the t’s are crossed, and Yellowstone manufacturing is underway! I want to say something satirical like “I never thought I’d live to see this day”, but truthfully this has been a long, long, loooooooong time in the making. General availability of Yellowstone is expected sometime around the middle of March. Development started in the summer of 2017, so you can do the math on total development time.

I’ve created a Yellowstone product page. This will be the official home for everything Yellowstone, including an overview of what it is and why you might want it, compatibility information, links to the instruction manual, firmware updates, and more.

Yellowstone is a universal disk controller card for Apple II computers. It supports nearly every type of Apple disk drive ever made, including standard 3.5 inch drives, 5.25 inch drives, smart drives like the Unidisk 3.5 and the BMOW Floppy Emu’s smartport hard disk, and even Macintosh 3.5 inch drives. Yellowstone combines the power of an Apple 3.5 Disk Controller Card, a standard 5.25 inch (Disk II) controller card, the Apple Liron controller, and more, all in a single card.

Need to attach a disk drive to your Apple II? Yellowstone should be your first choice, because it does virtually everything that every other Apple disk controller can do, plus more. The retail price for Yellowstone is planned somewhere in the mid-$100s range. This is a nice value, given that an Apple 3.5 Disk Controller Card costs $200+ and used Liron cards sell for $300+ on eBay, and Yellowstone can do much more than either of those cards.

Apple Disk Controller Card Comparison

Disk Controller Supports 3.5 inch drives Supports 5.25 inch drives Supports smart hard drives Supports Macintosh drives 20-pin ribbon connector DB-19 connector Number of connectors
Disk II
Controller Card
Disk 5.25
Controller Card
Apple 3.5 Disk Controller Card       1
Apple Liron Card         1
Yellowstone 1 2

[1] optional DB-19F connector

Since I know people are going to ask, I’m not taking pre-orders at this time, but you can sign up for the BMOW Newsletter if you want to be informed when Yellowstone is ready for sale. There should be plenty of Yellowstone cards to meet demand for at least a few months, so there’s no worry of an immediate sell-out. But in the medium to long term, the global semiconductor shortage and general meltdown of supply chains will be a problem. I couldn’t build additional Yellowstone cards right now, even if I wanted to, because the necessary parts just aren’t available anywhere. So if you want one of these, maybe don’t wait too long beyond March to grab one.

Want all the nitty-gritty usage details? You can read the Yellowstone instruction manual here. Now the waiting begins…

Read 23 comments and join the conversation 

23 Comments so far

  1. xot - January 13th, 2022 6:28 pm

    Congrats, Steve!

  2. Kay Koba - January 13th, 2022 10:50 pm

    Amazing! It’s finally completed!

  3. Jansky - January 14th, 2022 1:37 am

    The comparison table is cut on a smartphone.
    You should also put the Vtech UDC in this table, it supports Mac drives too and has two DB-19 connectors.

  4. Nick - January 14th, 2022 6:28 am

    Congrats! Looking forward to get one so I can use smartport hard drive and 3.5 mode with my FE and IIe.

    The manual states that you cannot daisy chain “dumb”/standard drives, even if they have connectors to do so. If you do by accident, I’m assuming no damage would occur, the 2nd drive just would not be recognized?

    Also the manual indicates the floppy emu should be connected directly to the 20 pin header, and is not listed in the table for the db19 connector. Does that mean it cannot be connected that way? It would be more convenient as I currently move my FE between my IIe (currently has the 5.25 controller), //c, and IIgs. All by connecting to the db19 port. I’m guessing it should work, but the manual isn’t clear on that.

  5. Steve - January 14th, 2022 7:50 am

    Yes, there’s no harm in accidentally connecting “dumb”/standard drives the wrong way. Depending on the exact drive setup, this may cause a drive collision error as described in the manual. Yellowstone will then deactivate all drives until the drive configuration is fixed. The table in section 3.4 lists all of the possible drive configurations supported by Yellowstone. Let me know if you see a better way to explain this information.

    Floppy Emu can be connected by DB-19 if you prefer. You’ll be going from 20-pin ribbon cable to DB-19 adapter to reverse DB-19 adapter to ribbon cable, so for most people it’s simpler to just connect the ribbon cable directly.

  6. Wyatt Wong - January 14th, 2022 10:27 am

    I didn’t see any DB19 connector in the YellowStone UDC.

  7. Steve - January 14th, 2022 10:58 am

    A DB-19F adapter (if needed) plugs into one of the 20-pin ribbon cable connectors. Other drives without a DB-19, like a Disk II or Floppy Emu, can plug in directly without an adapter. So you get the option of both connector types. Please see the product page and instruction manual for full details.

    I’m not sure if you meant “UDC” in the sense of the old Laser / V-Tech UDC card, but just to clarify Yellowstone isn’t a Laser UDC clone, even though they do have many commonalities. On the hardware side, Yellowstone supports naked 3.5 inch drives, Disk II drives, switchable Disk II Controller emulation, and user-upgradable firmware, none of which is available on the Laser UDC. It also supports smart drives and the Unidisk 3.5, which aren’t supported on most versions of the Laser UDC. On the software side Yellowstone has much better Apple IIgs support and GS/OS compatibility, faster 3.5 inch disk read performance, and overall better stability than the Laser UDC.

  8. Wyatt Wong - January 14th, 2022 11:30 am

    I read the manual after posting the comment and I realized the DB-19F connector is an add-on which required using the DB-19F connector plug into the 20-pin cable connector. Considering the backpane design of Apple IIe case, adding 2 DB-19F connectors to the YellowStone and then attach the DB-19F connector to the slot holes of Apple IIe is quite a challenge, especially that YellowStone does not support DaisyChain which I wish it could be a future enhancement.

    For UDC I simply use it as a shortcut of Yellowstone “Universal Disk Controller”. I did not meant to refer to the Laser UDC. I am sorry for any confusion arised.

  9. Nick - January 14th, 2022 1:31 pm

    Thanks for the info. The table in 3.4 makes things clear on what you should do. I was just curious on what would happen if you accidentally did something you shouldn’t do. Which I now see is stated below that table about drive conflicts.

    Out of curiosity (if it can be explained high level and easily), what is different about how the duo disk or FE in dual 5.25 mode can work on the db19 connector, but a daisy chain Apple 5.25 (like what was sold with the IIgs) doesn’t work?

    Also, where did you land with the plating and beveling options? I don’t think I saw a final decision in the last blog post. I’m personally less concerned about the plating than I am with beveling.

  10. Steve - January 14th, 2022 1:56 pm

    For the cable connections, if you’re using two DB-19F adapters, I recommend running both ribbon cables through a single backplane opening to the DB-19F adapters outside the computer case. That’s what the beta testers and I have been doing and it works OK. Cable management can sometimes be a pain, but generally no worse than for other disk controllers.

    Yellowstone actually does support daisy chaining two standard drives of the same type (secret feature alert!), which is how the Duo Disk and FE dual 5.25 mode are supported. Dual 3.5 works too. I intentionally didn’t mention this in the instructions, because it didn’t seem to offer any benefit over connecting the same two drives independently to the Yellowstone card, and I didn’t want to create more confusion. But I can see how it might be helpful from a cable management perspective, or to reduce the number of DB-19F adapters needed. I’ll try to find a way to explain this in the instructions without confusing everybody.

    The vendor I chose offered beveled edges for free, but didn’t have an option for hard gold plating, so that decision was easy. Although I’ll say I don’t think beveled edges are especially important here. The prototype cards have square edges and I didn’t find any problems with insertion, and none of the beta testers mentioned it. But the final card will have beveled edges.

  11. ianoid - January 14th, 2022 2:36 pm

    Great work! I can’t wait to get one! Does the card allow for the use of double density 5.25″ drives like the Rana Elite Two, Three and Four, in anything other than normal density mode?

  12. Nick - January 14th, 2022 7:23 pm

    Beveled edges I think is more important than the plating. So glad to hear it will be beveled.

    Yellowstone supports daisy chain of like for like drives? Any chance we’ll then see 3.5 dual drive mode for FE? Or porting over some of the other recent 5.25 changes; like WOZ format support or the faster menu navigation to Unidisk 3.5?

  13. Steve - January 15th, 2022 8:20 am

    Yellowstone can support two daisy-chained 3.5 inch drives or two daisy-chained 5.25 inch drives at its connector J1, if nothing is connected at J2. This doesn’t really offer anything different over connecting the same two drives separately to J1 and J2, and I didn’t want to confuse everybody by digressing into why specific daisy-chain configurations are/aren’t possible. Oh well…

    The FE items you mentioned are unfortunately all high effort, low value, so I wouldn’t expect to see them soon. For example Unidisk 3.5 menu navigation moves somewhat slower than other disk modes because the Unidisk emulation is actually running even while you’re navigating the menus. This is needed in order to respond to incoming command packets with “yes there’s a drive here, but there’s no disk in the drive”. The standard 3.5 inch disk emulation works quite differently from 5.25 inch, so unfortunately it’s not just a matter of copying over some 5.25 inch code and changing a few if() statements. The current FE priority is to redesign the device around different hardware, since both of the major ICs in the FE have become very difficult to find anywhere, and it’s almost impossible to manufacture new FE units.

  14. Leeland Heins - January 15th, 2022 9:05 am

    I have been waiting for this to be available since it was first discussed here several years ago. Really looking forward to being able to order!

  15. Wyatt Wong - January 15th, 2022 9:21 am

    Nice to know that YellowStone supports daisy chaining of dual 5.25 floppy drives and dual 3.5 floppy drives (UniDisk 3.5 or Apple 3.5 ?) using the J1 connector. The Laser UDC card also support this type of connection. And Steve is right that this approach to connect two drives of the same type into J1 can help to reduce using 1 DB-19F connector instead of 2 and this also benefit to the cable management. I am NOT sure about what is “FE” item mentioned in the comments above.

    On the other hand, the YellowStone instruction didn’t seem to explicitly differentiate the UniDisk 3.5 and Apple 3.5 drive. I guessed that’s probably because YellowStone is capable to support both types of 3.5 floppy drive, unlike using Liron and the SuperDrive Controller card which can only support UniDisk 3.5 and Apple 3.5 floppy drives receptively.

  16. Steve - January 15th, 2022 9:41 am

    Sorry for the mystery abbreviation, FE = Floppy Emu. The Yellowstone instructions describe the different options for standard 3.5 inch drives and for smart drives, the latter of which includes the UniDisk 3.5. Please search the instructions for “Unidisk 3.5”, you’ll see this is covered in several places including section 3, 3.2, and 3.4. Let me know if anything isn’t clear.

  17. Steve - January 19th, 2022 7:09 pm

    I’ve updated the Yellowstone instructions with better detail about daisy-chaining options. Pairs of standard drives may be daisy-chained together when the two drives are the same type: two standard 5.25 inch drives or two standard 3.5 inch drives.

  18. Leeland Heins - January 19th, 2022 7:56 pm

    Is there a way to get an email or something when Yellowstone cards are available for order? I want to make sure I get at least one, if not two before they sell out.

  19. Steve - January 19th, 2022 8:58 pm

    You can sign up for the BMOW Newsletter if you want to be informed when Yellowstone is ready for sale.

  20. Leeland Heins - January 20th, 2022 5:25 am

    Thanks, I am signing up.

  21. Tiersten - January 24th, 2022 6:14 pm

    Was the PCB photo edited? J4 looks like all 3 pads are shorted together and connected to the ground fill.

  22. Steve - January 24th, 2022 9:30 pm

    Yes, it’s actually a photo of the last prototype board since I don’t yet have the production boards. Photoshopped to clean up some of my soldering blunders.

  23. Martin - January 31st, 2022 7:33 am

    I can’t wait. I signed up for the newsletter!

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