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jaquinn
January 12th, 2018, 05:16 PM
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.

Chuck(G)
January 12th, 2018, 05:38 PM
Is it in the "big book" of Kaypro docs on Bitsavers?

At any rate, there were two versions of the mainboard, see page 18 (http://bitsavers.trailing-edge.com/pdf/kaypro/Kaypro_II_Dealer_Reference_Manual_1982.pdf)

jaquinn
January 12th, 2018, 07:21 PM
Is it in the "big book" of Kaypro docs on Bitsavers?

At any rate, there were two versions of the mainboard, see page 18 (http://bitsavers.trailing-edge.com/pdf/kaypro/Kaypro_II_Dealer_Reference_Manual_1982.pdf)

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.

LS120
January 22nd, 2018, 04:42 PM
the Micro C user group manuals tell about the 1793 and 1791.. and modding from 1 to other for better fdd.