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Unidisk Firmware Update for Floppy Emu

I’ve updated the BMOW Floppy Emu disk emulator firmware, adding new Unidisk and Smartport features for the Apple II family. After some quality hacking time with a Unidisk 3.5 drive and a logic analyzer, the hardware secrets were finally revealed! Thanks to Roger Shimada for providing the Unidisk to make this possible. Here’s a rundown of what’s new:

Unidisk 3.5 Emulation – The Floppy Emu can now emulate an 800K Unidisk 3.5 drive. Because the Unidisk uses the Smartport communication protocol, this new mode is very similar to the existing Smartport hard disk mode, with a few key changes. Unidisk 3.5 mode disk images are always 800K. They can be selected from a menu and ejected when needed, just like the other floppy emulation modes.

Apple IIc owners will probably get the most benefit from Unidisk 3.5 mode, because it’s the only 800K drive type supported by that machine. Apple IIe owners with a Liron disk controller may find it useful too, as well as anyone with an Apple IIe PDS card for the Macintosh LC. Unidisk 3.5 mode also works on the Apple IIgs, but the existing 3.5 inch floppy mode for the IIgs offers the same functionality with faster i/o speed.

Unidisk 3.5 Daisy Chaining – The new firmware also enables a Floppy Emu to be daisy-chained behind a real Unidisk 3.5, when the Emu is in Smartport or Unidisk 3.5 emulation modes. Unfortunately, to gain the benefit of this change, an external hardware modification is also required. If you have an urgent need for Unidisk daisy chaining, see the cable-hacking suggestion in the comments of the linked post.

Unidisk/Smartport Cold Boot Speedup – The Floppy Emu initialization delay from power-on to ready has been dramatically improved for Unidisk 3.5 and Smartport emulation modes. This makes it possible to cold-boot an Apple IIe directly from an Emu attached to a Liron card. Previously it required a warm start or PR#7 command to reinitialize the Smartport once the Emu was ready, but that’s no longer necessary. This change may also help cold booting from Smartport on the Apple IIc+, which was hit-or-miss with the old firmware. I don’t have a IIc+, so please let me know how it fares with yours.

Get the Firmware

Firmware 0.1X contains all three new features described above. The Unidisk 3.5 emulation required major code changes which may have impacted other features, so if there’s a problem I’ve also included firmware 0.1V as an alternative and fallback. 0.1V contains only the daisy chaining and cold boot speedup features.

Floppy Emu Model A – apple-II-0.1X-F20
Floppy Emu Model B – apple-II-0.1X-F21-modelB

Try version 0.1V if you have trouble with 0.1X
Floppy Emu Model A – apple-II-0.1V-F20
Floppy Emu Model B – apple-II-0.1V-F21-modelB

Read 8 comments and join the conversation 

8 Comments so far

  1. John Brooks - August 11th, 2017 11:18 pm

    Very cool! Any chance the new Unidisk 3.5 emulation includes the embedded 6502? IE, does it support user-executed programs loaded into the Unidisk 3.5?


  2. Steve - August 12th, 2017 5:04 am

    No, that would be a little crazy. 🙂 It’s basically an ejectable 800K version of the existing Smartport hard disk emulation.

  3. Joseph Migeed - August 12th, 2017 7:07 am

    Incredible stuff. Thanks for all the great work.

  4. Thomas Wolfe - August 12th, 2017 10:39 am

    Does the EMU have the ability to scroll long filenames? Can’t tell from the manual.

  5. Steve - August 12th, 2017 11:24 am

    It shows ellipses in the middle part of the name if it’s more than 21 characters. see

  6. AVRkiller - August 20th, 2017 7:08 am

    I did a little testing with an enhanced //e booting from a Liron card using apple-II-0.1X-F21-modelB and it worked fine.

    The IIc Plus is still too fast. I shot some video trying to boot off of the FloppyEmu then realized that’s not useful because it does not demonstrate how little time there is.

    I grabbed a UniDisk 3.5 and a freshly formatted ProDOS diskette. The Floppy Emu was also connected to indicate its state. The video at shows the IIc Plus being turned on, the UniDisk 3.5 discovered, then boot block and volume directory (4 blocks) are read.

    Additionally, not only the IIc Plus boots too fast for a power up of the Floppy Emu, a PR#5 didn’t work either. I had do a Control-Command-Reset. (The IIc Plus keyboard open and closed Apple keys got relabeled.)

  7. Steve - August 20th, 2017 7:52 am

    That’s too bad. With the new firmware, Floppy Emu is ready for Smartport I/O in about 100 milliseconds after power-on: even before the happy face is displayed on the screen.

  8. Michael - September 17th, 2017 11:54 pm

    Tried the Unidisk and Smart Port HD for the first time on my Apple IIc and both work great including from power on. Until now, I hadn’t dabbled with the Smart Port HD and it is awesome. I can load all of my basic programs into one place without having to switch floppies. Thanks!!!

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