


                  HOOKING A 5.25" DRIVE TO YOUR AMIGA 

                                               by Les Ayling

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    Hooking up a standard 80 track, double-sided, 5 1/4" floppy disk drive
   as drive df2: or df3:

    Looking at the connector from the back side of the external drive, the
   pin out is as follows:


            712  11  10  9   8   7   6   5   4   3   2   1


                 23  22  21 20  19  18  17  16  15  14  13


    34 Pin edge connector pin-out is as follows:


             34 32 30 28 26 24 22 20 18 16 14 12 10  8  6  4  2


             33 31 29 27 25 23 21 19 17 15 13 11  9  7  5  3  1



    Wire a DB25 (RS-232) connector with pins 13 and 25 cut off per the
   following configuration:


              34 Pin     23 Pin

              -----------------

              34 ---------  1

              32 --------- 13

              30 ---------  2

              28 --------- 14

              26 --------- 15

              24 ---7---- 16

              22 --------- 17

              20 --------- 18

              18 --------- 19

              16 ---------

              14 ---------  9

              12 --------- 21

              10 -- tie to ground, keep the motor running all the time

               8 --------- 22

               6 --------- 20

               4 ---------

               2 ---------

   all odd numbered pins of the 34 pin connector should be tied to pins
   3, 4, 5, 6 & 7 of the 23 Pin connector (grounds).


    In addition, pin 11 of the 23 pin connector should be wired to a
   momentary push-button that can be activated whenever a diskette is
   removed and replaced with another.  This tells the DOS that a different
   diskette has been inserted into the drive.  Simply change the diskette,
   push the button and hold until DOS accesses the drives.  The switch may
   then be released.  This function is necessary due to the fact that the
   DOS seems to read the directory of the current diskette into ram, and
   unless the DOS is told of another diskette being used, it will either
   ask you to replace the diskette that was in the drive or write to the
   diskette using parameters from the previous disk.  This, of course, is
   very undesirable.


    Also, note that the drive must be connected when booting DOS or it
   will not be noted as being on-line.  The diskette does not have to be
   inserted, just the drive plugged in.


    Do not make any connections to the 23 pin connector, pins 23 or pin
   12.  These pins provide power to the Amiga drive 1 and may not be used
   to power an external 5 1/4" drive.  An external power supply must be
   used.


    The 5 1/4" drive selection header may be programmed as drive for drive
   2.  Drive 1 selects as DF2: and drive 2 selects as DF3:.


    A motor on latch circuit may be built to eliminate the motor
   continuously turning, however, the way indicated above is the quickest
   and simplest method to get another drive on-line.


    After this procedure is completed, the 5 1/4" drive may be used just
   as any normal Amiga drive.


    Considering the $295.00 list price of the Amiga drives, versus about
   $50 dollar price of 5 1/4" drives, it's a real bargain.


    *** As always, with any hardware project -
    (1) - if you are not sure of what I am talking about, get
   knowledgeable help and
    (2) - TRIPLE CHECK your work before plugging in the new drive.



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