*-*-*›        The XF551 Enhancement›        Review by David Bryant (GKAUG)›› (Ed.  While  this  is  an old article,› (February 1989) I'm sure many  of  you› have  not  seen  it,  and  even if you› have,   it's   valuable   info,  worth› reprinting,   specially  if  you  have› purchased an XF551 since  the  article› appeared. A.P.)›› How many of you have taken your trusty› double sided floppy  disk,  punched  a› write  protect hole in the jacket, and› flipped   it  over  to  write  on  the› reverse  side?   If  you're  like  me,› you've  done  it many   times.   So  I› thought nothing about it when I got my› XF551 disk drive. I just put the  disk› in  and  loaded  those  basic programs› like nothing was different.›› I was wrong.  The first time I went to› format  a  disk, (using Atari DOS 2.5)› the drive protested and gave an  error› #173.   I  also had problems trying to› write to the back side of disk in  the› XF551.   I  then  got  a  gift  from a› friend, a modification for  the  XF551› that  allows  it  to  operate  like my› trusty   1050.    Now   formatting  or› writing to the back side of  disks  is› no  problem.  This handy mod is called› The XF551 Enhancement,  from  Computer› Software Services.›› If you look at a floppy disk, you will› see a smaller hole near  the  edge  of› the large hole in the center.  This is› the index hole and some drives use  it› to tell when it is at the beginning of› a track.  The 1050 does not,  so  when› you  flip  the disk, it doesn't matter› if there is no  hole  on  the  reverse› side.  The 1050 uses a signal from the› RAM I/O  TIMER  chip  to  provide  the› index  pulse  to   the   Floppy   Disk› Controller chip.›› The  XF551 uses a index hole sensor to› provide the index  pulse,  and  that's› where  this  kit is needed!  After you› install this kit, a switch on the back› of  the  drive  allows  you  to choose› XF551 or 1050 mode.  In one  position,› the drive acts like a standard XF551. › In the other position, you can  format› and  write  to  the  back side of disk› like the 1050.  Also you don't have to› punch  write  protect  holes  in   the› jacket anymore.›› The kit consist of an epoxy shell with› the circuitry inside  and  a  switch. › About  seven wires need to be attached› to the circuit board and write protect› sensor inside the XF551.  Instructions› included with the kit are very easy to› follow.   I  would  however remove the› circuit board  from  the  drive  (only› three  more  screws) when soldering to› the IP jumper location.  I located the› switch above the Drive Select Switches› and the epoxy shell next to it  inside› the  rear  cover.   There's  plenty of› room   and  everything  goes  together› easily.›› I  wish  to  thank  Computer  Software› Services for a good product.   Current› cost  is  $29.95 and they will provide› installation    to    those    without› soldering   skills.    They   may   be› contacted at:›› Computer Software Services› 465 Kilbourn Rd.› Rochester, NY.  14618› Phone: (716) 467-9326› or›› P.O.  Box 17660› Rochester, NY.   14617›› (Ed.  David  Bryant is a devoted ATARI› user, treasurer of G.K.A.U.G., and may› be  contacted  at  the   clubs   BBS.)› (Phone: 616-657-2665).›› NOTICE:    This   article   originally› appeared in the February,  1989  issue› of Atari Interface Magazine and may be› freely  distributed  or  reprinted  in› non-profit User Group publications  as› long as the article's author and Atari› Interface Magazine  are  credited  AND› this  notice  is  reprinted  with  the› article.   All other publications must› obtain written permission from Unicorn› Publications,  3487  Braeburn  Circle,› Ann Arbor, MI 48108, Phone: (313) 973-› 8825 before using this article. (Ed. I› understand  that  UNICORN is no longer› in existance. A.P.)›› ----------------end-------------------›