[Coco] FDD 26pin to 34pin
Mike Pepe
lamune at doki-doki.net
Mon Aug 7 19:56:05 EDT 2006
Chester A Patterson wrote:
> I think now I've got it gentlemen.
> Passing this info for your far more knowledgeable review and advice.
>
> Coco FDD interface (Disto) PC FDD interface FDD
> 26pin (Citizen OSDC)
> ------------------------------------------------------------------------
> ------
> 1 Gnd Gnd
> +5V
> 2 N/C Density Select INDEX
> 3 Gnd Gnd
> +5V
> 4 N/C N/C
> DRIVE SELECT 0
> 5 Gnd Gnd
> +5V
> 6 N/C N/C
> DRIVE SELECT 1
> 7 Gnd Gnd
> +5V
> 8 INDEX INDEX
> READY
> 9 Gnd Gnd
> +5V
> 10 DRIVE SELECT 0 MOTOR ON DRIVE 0 MOTOR ON
> 11 Gnd Gnd
> N/C
> 12 DRIVE SELECT 1 DRIVE SELECT 1 DIRECTION SELECT
> 13 Gnd Gnd
> Gnd
> 14 DRIVE SELECT 2 DRIVE SELECT 0 HEAD STEP
> 15 Gnd Gnd
> Gnd
> 16 MOTOR ON MOTOR ON DRIVE 1
> WRITE DATA
> 17 Gnd Gnd
> Gnd
> 18 DIRECTION SELECT DIRECTION SELECT
> WRITE GATE
> 19 Gnd Gnd
> Gnd
> 20 HEAD STEP HEAD STEP
> TRACK 00
> 21 Gnd Gnd
> Gnd
> 22 WRITE DATA WRITE DATA
> WRITE PROTECT
> 23 Gnd Gnd
> Gnd
> 24 WRITE GATE WRITE GATE
> READ DATA
> 25 Gnd Gnd
> Gnd
> 26 TRACK 00 TRACK 00
> SIDE 1 SELECT (HS)
> 27 Gnd Gnd
> 28 WRITE PROTECT WRITE PROTECT
> 29 Gnd Gnd
> 30 READ DATA READ DATA
> 31 Gnd Gnd
> 32 DRIVE SELECT 3 HEAD SELECT
> 33 Gnd Gnd
> 34 N/C DISK CHANGE
>
> The two FDD 26pin I have are from a TANDY 1400LT, they have the 0123
> switch onboard but the manual, from which I took the above info,
> mentions not the switches that I could find (they were set to 0 and 1
> when I yanked the drives) But the 1400 has a provision to add an
> external FDD and at the flip of a switch (on the side of the 1400) to
> make the external FDD either A or C drive.
>
> So, I guess my lingering question is: where/how do I connect the Drive
> Select lines to the 26pin FDDs?
>
> Thanks.
>
> /Chester
The floppy drives use a bus topology. All signals go to all drives.
-Mike
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