PART 1:

Empty drives on the Amiga make a clicking noise.  With one empty drive in a
quiet room it is annoying.  With two it gets on the nerves.  With three it
drives one up the wall.  And with four... well by that time you are over
the wall, and down the other side.

There is hope!  No longer will you need to stick a disk into a drive just
to get it to shut up.  I hereby unveil:

noKLICKstart

A program to patch your V1.2 Kickstart disk.  After the modification the OS
will test for disk insertion silently.  If you have an Amiga with Kickstart
in ROM you have just discovered a disadvantage of Kickstart in ROM.

When Kickstart V1.3 comes out you won't need this.  It will be part of
the Operating System.  Right Dale? 1/2 :-)


Technical mumbo jumbo:  It's quite simple, really.  The /CHNG signal is set
low and latched by the drive when a disk is pulled out.  In order to see if
a disk has been inserted the latch must be unlatched.  This is done by
stepping the head.  Normally the Amiga goes from track 0 to 1 and back.
This is what makes the noise.

Now these drives all have track 0 sensors.  You can't make the drive go
past track zero.  You can, however, reset the latch by _trying_ to step out
past track zero.  Sony literature confirms that the latch will be reset,
but the head will not move.  Great!

All that is needed is to patch Kickstart.  You need to change one solitary
bit, and then fix the checksum.  Which bit??  heh... heh... there are
2,097,152 choices... what's it worth to 'ya?  Nothing???  Ok then, I'll
tell you.  Change the long word at $00FE99E8 from $086B001 to $08EB001.  I
don't know where the real checksum is kept, so I just mangle the Copyright
notice by changing $00FC007C from $6D6F646F to $6CEF646F.

This turns a "BCHG" instruction into a "BSET".

What? The Kickstart ram is not writable??  You mean you don't have a button
to do that??  Gee.  Maybe you'd like a program.  Here's one!


PART 2:

After my posting of the Kickstart disk patch to eliminate empty drive
click several people wrote to me worried that it might not work
on their machines.  If they had only tried it first... :-).

After coming up with the idea I tested it. (Insert delay of about 1.5 years)
I then contacted Sony.  Their rep and spec. sheet says that the method will
work.  (Sony invented the 90mm drive then got together with other manufactures
to make it a standard).  The NEC rep said the same thing... and that the
method chosen was quite common (and the method the Amiga uses quite wierd).

Drives from any manufacturer should be just fine.  It has been tested on
drives from Sony, NEC, Mitsubisi and Panasonic.  (not all of those where Amiga
drives).  Have any other brands been used in the Amiga?  Probably.  Just
count the number of different style plastic eject button mouldings. :-)

Oh, and before you ask, this Kickstart patch is not going to bother any
software.  Software could not care less about the empty drive detection
method.