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Thread: Epson PF-10 floppy drive - 8 or 9 sectors per track?

  1. #1

    Default Epson PF-10 floppy drive - 8 or 9 sectors per track?

    The documentation says 9, but the logical format only shows 128 byte sectors from 1-64, not 1-72. Did it have 9 sectors and the 9th was just not read/written from?

    logical format 40 tracks, 1 side, 64 sectors, 128 bytes per sector (40*1*64*128 = 327680 bytes = 320K)

    TF-20/TF-15 40 tracks, 2 sides, 16 sectors, 256 bytes per sector (40*2*16*256 = 327680 bytes = 320K)

    PF-10 40 tracks, 2 sides, 8 sectors, 512 bytes per sector (40*2*8*512 = 327680 bytes = 320K) <--- what I think it should be
    PF-10 40 tracks, 2 sides, 9 sectors, 512 bytes per sector (40*2*9*512 = 368640 bytes = 360K) <--- what the PF-10 manual says

    The logical format is what the computer uses to talk to the drive with over the serial protocol...

  2. #2

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    Hi,

    The PF-10, as do the QX-10 and TF-20, use 9 sectors per track. The 320 K is because the first four tracks are reserved for the QX-10 or TF-20 BIOS and the last track isn't used at all.

    Greetings,

    Fred Jan

  3. #3

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    Hi Fred Jan,

    First, thanks for your website/information on the PX-8, it has been very useful.

    I pulled this from the technical/user manuals:

    TF20
    80 tracks (40 tracks * 2 sides)
    16 sectors per track
    256 bytes per sector
    (320K)

    TF15
    80 tracks (40 tracks * 2 sides)
    16 sectors per track
    256 bytes per sector
    (320K)

    PF10
    80 tracks (40 tracks * 2 sides)
    9 sectors per track
    512 bytes per sector
    (360K)

    The logical disk format however for all 3 drives is identical:

    40 tracks
    64 sectors per track
    128 bytes per sector
    (320K)

    They translated for the 2 sides and larger sector sizes by moving them into the sector number via translation. So for the logical format sectors 1-32 are likely side 0, and logical format sectors 33-64 are likely side 1. Logical sectors 1-2 are likely sector 1 on a TF15/TF20, but logical sectors 1-4 are likely sector 1 on a PF10.

    The skipped tracks you mention are part of the logical format as well. Their exclusion is why CP/M sees the disks as 280K disks and not 320K disks (320K * 35 / 40 = 280K).

    logical disk format
    tracks 0-3 and 39 reserved
    track 4 directory and file blocks
    track 5-38 file blocks

    I have a feeling that physical sector number 9 on both sides is not used on the PF10, there is no place it can map to in the smaller logical format.

    When you prepare a disk for use with the TF20 (that boots from disk), do you have to format it and then copy it from another disk with the 4 tracks written with the OS the TF20 needs?

  4. #4

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    Quote Originally Posted by alank2 View Post
    I have a feeling that physical sector number 9 on both sides is not used on the PF10, there is no place it can map to in the smaller logical format.
    I always forget even CP/M disk formats are always more complex than I remember. I do know the PX-8/PX-4 can't see the difference between a booted TF-20 and a PF-10. So the PF-10 might use 512 byte sectors, it pretends to have 256 byte sectors (at EPSP-protocol level). I do have a PF-10, but it is broken, and no disks. So it is likely the 9th s

    Quote Originally Posted by alank2 View Post
    When you prepare a disk for use with the TF20 (that boots from disk), do you have to format it and then copy it from another disk with the 4 tracks written with the OS the TF20 needs?
    Just recently I actually used the COPYDISK.COM utility to create a physical copy of a TF-20/PX-8 disk. COPYDISK can format and copy system and/or data tracks.

  5. #5

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    Hi Fred Jan,

    Another question - I noticed in the protocol page you have:

    https://fjkraan.home.xs4all.nl/comp/hx20/epsp.html

    That there are commands for a display or monitor. Did the HX-20/PX-8/PX-4 have a monitor that could be connected to the high speed serial in place of the internal LCD ???

  6. #6

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    Another another question! In the page you have about Epson EPSP, it shows the ENQ procedure as an EOT, then P1/DID/SID/ENQ. Then it says P1, 00=SELECT and 80=POLLING. SUPPORT SELECT ONLY.

    Oddly in the captures I've done between the PX-8 and PX8VFS, the PX-8 sends out: <EOT 0x04> <SEL 0x31> <DID 0x31> <SID 0x22> <ENQ 0x05>

    Why does it use SEL 0x31 instead of SEL 0x00? Also, what was the 0x80 POLLING for?

  7. #7

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    Hi Alan,
    Sorry I haven't replied to your email. Real Soon Now (tm), I promise!
    First, I am 99% certain the pf10 actually has 9 sectors of 512 bytes and the last is simply not used. The on-board controller does the translation to 128 byte records/sectors for CP/M.
    Second, the polling was apparently intended for some use that was never implemented. If you look through the full documents of the EPSP protocol it has a LOT of stuff that is irrelevant to the PX-8 and possibly to all the relatives. Apparently Epson had big plans that never happened.
    Third, I think I have the answer somewhere about the SEL 0x31 but off the top of my head. I will try to have a look later tonight.

  8. #8

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    There was a monitor adapter available for the HX-20. It is apparently quite rare. It was expensive even then.

  9. #9

    Default

    Quote Originally Posted by alank2 View Post
    Another another question! In the page you have about Epson EPSP, it shows the ENQ procedure as an EOT, then P1/DID/SID/ENQ. Then it says P1, 00=SELECT and 80=POLLING. SUPPORT SELECT ONLY.

    Oddly in the captures I've done between the PX-8 and PX8VFS, the PX-8 sends out: <EOT 0x04> <SEL 0x31> <DID 0x31> <SID 0x22> <ENQ 0x05>

    Why does it use SEL 0x31 instead of SEL 0x00? Also, what was the 0x80 POLLING for?
    The documents imply SEL is 0x00 or 0x01, but I found they were actually ASCII "0" or ASCII "1". I believe the "reply" is a "1" and that is what you are seeing.

  10. #10

    Default

    Thanks for the help! I've got it working pretty well now. Found a bug in my checksum that only showed its ugly head when the checksum was 0, but I got that fixed now. I've got it reading at a whopping speed of 1.72 K/s.

    Discovered that COPYDISK will only copy from the low drive to the high drive oddly. You can do a copy from D to E and it will do the fast drive copy (drive unit does it, no data transferred to the PX-8, super fast), but if you try to do the E to D copy, it reverse the slow mode. This is odd considering that the command includes a drive to copy that could be specified as 2 and not 1. Apparently it can fast copy 1->2, but not 2->1. Is there copydisk documentation anywhere?

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