Epson TF-20 Boot Disk Creation

As I mentioned in an earlier entry, the Epson TF-20 5.25 inch floppy drive requires its OS to be loaded from disk before the unit will communicate and work with the PX-8.

My over riding intention since acquiring the TF-20 has been to back up the single boot disk that came with the system given that it’s over 20 years old and should the disk have failed the drive would have been rendered useless.

My initial attempts failed, although I have a copy of Copydisk and it was apparently successfully formatting and creating disks with the system tracks, when I tried to boot the drive with those disks, no luck.

I spoke to F J Kraan who advised that the proper disk type was Double Density (DD) as opposed to the High Density (HD) that I was using.  I tracked down some DD disks and repeated the process and it works.  I have of course therefore made several back up boot disks and feel somewhat relieved.

Incidentally the HD disks give the impression of working for general file usage, but success is intermittent, with occasional bad sector errors.  Meanwhile the working PF-10 has decided to well, stop working, hopefully this last burst of activity wasn’t its last hurrah.

I’m waiting on some C size batteries to try in the drive to see if it’s a battery issue or not.  Meanwhile I took one of the PF-10’s apart and took some crumb trail pictures with my phone.

(Update:- I’ve installed the four new C size batteries in the PF-10, but still no joy, harumph!)

8 thoughts on “Epson TF-20 Boot Disk Creation

  1. That battery in the last picture might need swapping out? At 100mah I would guess it’s something to do with backup? Mind, I suppose floppy drives don’t use a great deal of juice. ‘K4 PF1’ is the EPROM containing the microcontroller code – the sticker protects the erase window from being exposed to UV. My guess would be that the socketed chip below the EPROM is the processor. Hope you got it back together ok!


  2. Indeed, the battery on the board kicks in when the main battery runs out and the battery light on the unit starts to flash warning you to stop activity and recharge. What I don’t know is whether you need a functioning, healthy backup battery regardless of the charge in the main battery?

    Swapping out the backup battery is beyond my abilities as it’s soldered in. I think I’ve reassembled the unit successfully, do you have any idea what the odd looking six prong riser plug thingamyjig in the third picture labelled CN3 is for?


  3. well, it’s a connector of some description, CN being a standard was of labelling connectors 😉 However, what it is for I don’t know – not sure why it’s so long, seems a bit strange If I had to guess I would say it’s either a test point used during manufacturing, or, it’s a connector for a daughter card that sat on top and plugged into it.

    Regarding batteries – sometimes kit won’t function with a dead battery. If it’s a backup battery I would say it’s highly likely the design relies on it having charge. Not sure what the implications of it not having charge are mind. Well, not in a disk drive anyway.


  4. Hey cool thing! I’m new with the PX-8 and the TF-20 and I’m looking for a step-by-step instruction to bring the TF-20 back to life. Do you have such an instruction? My TF-20 seems to work: If I insert a DD floppy into the left drive, the LED blinks and the drive makes some noise. But how can I make such a boot disk? Maybe you can help me a bit…


    1. For information, my HX-20 is still just about working. I think that my TF-20 still works, although the disk insert mechanism needs help. The drive makes the correct noises on booting. BUT my TF does not communicate any more with the HX, I suspect a mechanical/solder problem near the HS socket on the HX, too much plugging/unplugging. That aside, I use the 22DISK system on an old PC, and this knows the TF-20 disk format, so I can read/write files from the TF within limits. I have extracted copies of the system tracks etc. I have the original TF disk, and at least one working copy. In case anyone needs info?


  5. Hello, I am looking for a cable from PX-8 8 pin mini DIN to TF-20 DIN.
    Have you a wireing plan?

    Please stay save
    Greetings Dirk from Germany


    1. Thanks for this information. I know about this page. I have the boot floppy and the HX-20 calbe. but now I need a PX-8 cable or the wirering plan of the PX-8 cable.

      Thanks for helping.
      Greetings Dirk


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