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Thread: Zenith Z-171 Z-170 ZFL-171-42 : XT-CF card

  1. #1

    Default Zenith Z-171 Z-170 ZFL-171-42 : XT-CF card

    So I started a project to create an XT-CF card based on the Lo-tech design a month ago.
    Making some progress.
    First major issue was that the "standard" ISA port on the Z170 is not well documented (in the user manual and the service manual)
    * it is wired backwards relative to the standard port, so my layout was a mirror image of what was needed
    * power pins are not correctly documented

    Despite those setbacks I have now got a flashable card installed in my Z171.
    I'm now debugging the specifics of the actual bios used, the settings, getting an FDISK.COM that works and recognizes the HDD etc etc.

  2. #2

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    Can you share your documentation? I would like to do a similar project for the zwl-180 series.

  3. #3

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    Sure happy to.
    Does that computer have an isa slot internally?

  4. #4
    Join Date
    May 2011
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    I'd be interested in seeing your schematics and slot documentation if you share them. I had to do (probably similar) adaptations for the cards I've been making for the "PLUS" bus in my Tandy 1000 EX, which is likewise ISA-but-*not quite* on a different connector.

  5. #5

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    I've been able to get something working reasonably well, with caveats.

    * while it is possible to use DOS newer than 3.1, newer DOS tends to not work great with the floppy drives in the Z171. Recommend sticking with stock Zenith 3.1 MSDOS.
    * start up of the machine suffers from a defect which may or may not be resolved. Basically, to boot up or reset the machine you must power down for 10 seconds, boot once, soft reset before boot attempts to read from CF card, and then let the next boot proceed. It is a bit clumsy but manageable.
    * I'm using R602 XUB firmware

    The ISA socket is wired up mirrored relative to the standard card. This means I need new PCBs.

    I'll have to post the PCBs with instructions at Oshpark when the next boards are verified.

  6. #6

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    Quote Originally Posted by Twospruces View Post
    Sure happy to.
    Does that computer have an isa slot internally?
    Not a standard slot, no. It has a 20 pin and a 26 pin connector which normally has a sub-card plugged in which the JVC HDD attaches to. I presume that it is a HDD controller card that communicates via what is essentially a custom-connected ISA slot or slots; I'm working on getting a wiring diagram for the connectors.

    What would be most helpful is any sort of documentation you have from the slot back to chips on the board.

  7. #7

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    Didn't realize the ZFL-171 could have a hard drive though I was hoping someone would design a flash adapter for the partial ISA bus sticking out the back?

    Mine is a ZFL-171-82 (dunno what the 82 means but i think it is a fully upgraded model). Edit this was a computer reset find.. it was located in a filing cabinet in the laptop room. I saw at least one more on the stairs while I was there.

    https://www.facebook.com/chase.rayfi...6390621107108/

  8. #8

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    Yes that is the point of this project. Compact flash "HDD" . Its working well with some simple rules for how to power up and reset. I have a new pcb to test out due to the reversed pinout of the connector. Saw you changed to NEC V20. Is that a VMOS CPU?

  9. #9
    Join Date
    May 2011
    Location
    Outer Mongolia
    Posts
    1,471

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    Quote Originally Posted by Twospruces View Post
    Saw you changed to NEC V20. Is that a VMOS CPU?
    My rusty memory is that the V-20 is CMOS but it includes internal pull-ups to make it TTL compatible? (Like HCT series 74' logic?)

    If you want one I can kind of vouch for this seller, at least so far as I received a CPU that works fine in my old Tandy.

  10. #10

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    Yah thanks. Checked that datasheet and it is 10mA per MHz like the 80C85...so seems like a good upgrade.

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