[Coco] FDD 26pin to 34pin
gene.heskett at verizon.net
Tue Aug 8 11:42:59 EDT 2006
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.
>The floppy drives use a bus topology. All signals go to all drives.
>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?
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Copyright 2006 by Maurice Eugene Heskett, all rights reserved.
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