Schematic for Kaypro II with WD1791 FDC

[jaquinn]

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)]

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

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

 

[jaquinn]

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.

 

[LS120]

the Micro C user group manuals tell about the 1793 and 1791.. and modding from 1 to other for better fdd.