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Thread: Schematic for Kaypro II with WD1791 FDC

  1. #1
    Join Date
    May 2012
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    Default Schematic for Kaypro II with WD1791 FDC

    I am restoring two Kaypro II and have discovered they have different main boards.

    One matches the schematics in any of the Kaypro Technical manuals I can find online. It has a WD1793 floppy disk controller.

    The other has a WD1791 FDC and a number of additional 74xx parts around the board.

    https://photos.app.goo.gl/Sh1FLf9QnYcEkln22

    I haven't seen any schematics for the Kaypro II that show a WD1791 FDC.

    Has anyone else seen such a document/schematic?

    Thanks for your help.
    SBC6120 / PDP11 + VAX / TRS-80 / Kaypro / Northstar / Home Brew Z80 / BBC / Amstrad / Commodore
    http://www.quicktrip.co.nz/jaqblog

  2. #2
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    Default

    Is it in the "big book" of Kaypro docs on Bitsavers?

    At any rate, there were two versions of the mainboard, see page 18

  3. #3
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    Default

    Quote Originally Posted by Chuck(G) View Post
    Is it in the "big book" of Kaypro docs on Bitsavers?

    At any rate, there were two versions of the mainboard, see page 18
    Unfortunately no. The earliest Technical Guide there (and anywhere I can find) is labelled 1484-C and while there are two boards, they both have the 1793 FDC.

    Interesting though.... there is a reference to the 1791 FDC in the "Kaypro II Dealer Reference Manual 1982" on Bitsavers. Page 18 has a table that lists the differences between what they call main board versions 81-110A and 81-110B1 and 81-110A is listed as having a 1791. No schematic but the rest of the table helps. The requirement for 2 x 74LS242 inverting transceivers right next to the 1791 makes sense given the difference between the 1791 and 1793 is supposedly the inversion of the data lines.
    SBC6120 / PDP11 + VAX / TRS-80 / Kaypro / Northstar / Home Brew Z80 / BBC / Amstrad / Commodore
    http://www.quicktrip.co.nz/jaqblog

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