[Coco] FDD 26pin to 34pin

[Gene Heskett]

On Tuesday 08 August 2006 09:51, Chester A Patterson wrote:

>OK. I figured as much. Most signals are no problem, DS0, DS1 and DS3

>(HS) have where to go... (please be patient, I'm learning and

>remembering, fast) I see now why we can only have up to 4 SS FDDs or 3

>DS FDDs. However, where to send the Coco DS2 signal on the 26pin FDD?

>And I guess the READY signal remains N/C?

>

This might be a  case of nobody ever used it (in a pc) so the 3rd drive 
feature went away.  In that event, twisted cable for the 3rd drive is 
required in order to steer DS2 to the DS1 pin on the third drive.


>Thanks.

>/Chester

>

>>>>>> <<<<<

>

>The floppy drives use a bus topology. All signals go to all drives.

>

>-Mike

>

>-----Original Message-----

>From: Mike Pepe [mailto:lamune at doki-doki.net]

>Sent: Monday, August 07, 2006 5:56 PM

>To: CoCoList for Color Computer Enthusiasts

>Subject: Re: [Coco] FDD 26pin to 34pin

>

>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 (HS)

>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


-- 
Cheers, Gene
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Copyright 2006 by Maurice Eugene Heskett, all rights reserved.