Here's the un-official, bootleg Atari ST emulator for the Amiga!
This one's for NTSC.

It ran okay on an A500 with 1 meg of chip ram & 8 megs of fast ram
(but I doubt it needs that much), kickstart 1.3, a hard drive and two
floppies, and a stock 7.15 mHz 68000.

It ran okay from an icon.

It did NOT run okay on an A1200.

I'd start out in high res because it's the fastest of the three modes.
The color modes are jerky.

It's got a version of TOS 1.2 in it with some strange text in the
alert boxes.

According to a performance program I ran, the emulator runs at less than
1/2 the speed of an ST in the color modes, and about 75% the speed of an
ST in high res monochrome.

There's some problems reading the floppy drives, even the ones the emulator
formats, and you can't change resolutions from the desktop (you must pick
a res at the beginning).

Press both mouse buttons to reset the emulator.

The Amiga's power LED will flicker to let you know the emulator is working.
If it ever stays on or off, it's time to CTRL/A/A if ya know what I mean...

There is no sound support at all.

This emulator will even run executable boot sectors on disk, meaning it
can spread ST viruses!  (It showed "VIRUS FREE DISK", a message that
VKILLER leaves on your floppies for you)

Compatability:

I tried several ST programs on this emulator and a surprising number of them
worked!  Here's what I tried:

Program:               Functionality:           Resolution:

ST Control Panel       perfect                  all 3
Desk accessories
  in general           pretty good
Degas Elite            so-so                    all 3
Ripcord                perfect                  low
Format                 so-so                    all 3
Format3                perfect                  med or high
Magic Shadow
  Archiver             perfect                  med or high
Tunnel Vision          nope
Stonage Willy          nope
Haunted House          nope
Robotz                 nope                     
Arcshell, Arc, Lha,
  etc.                 perfect                  med or high
Fujiboink!             so-so                    low
Bugs                   nope
MidiMaze II            so-so (couldn't move)    low or high
Daleks                 perfect                  med or high
VKiller                perfect                  med or high
Amiga_Fun (Joke        almost                   med
  Amiga Emulator on
  the ST)
Megaroids              so-so (couldn't move)    med or high
Major Motion           nope
Boink demo             nope (too bad, to!  It goes faster on the ST
                       than the Amiga's Boink demo!)
PD Joust               nope
Qindex22               Perfect                  all 3
Motorcycle             nope
Atom Smasher           Perfect (slow, tho)      Low
NeoChrome              nope
Fcopy3                 so-so (thought disk was  med or high
                       write protected)
Procopy                so-so (same thing)       all 3
Raytraced ball demo    perfect (but slow)       low
  (ball bounces on a
  mirror next to 2 other
  balls that don't)
Go                     nope
Experiment 42          nope
Wheel of fortune       nope
Ringball demo          perfect                   low
50HZ.PRG               so-so (it loaded, ran,    all 3
                       and exited just fine like
                       it was s'posed to, it just
                       didn't DO anything...)
Mazemaker.TOS          Perfect                   all 3
Stats.PRG              Perfect                   med or high
NeoDesk 3              Perfect (wow!)            all 3
GFA Basic 3.5e         nope
GFA Compiler           almost (messed up when    all 3
                       linking)
Compiled GFA Basic     Perfect (weird, huh?)     all 3
  Programs
DPAINT ST              almost (mouse didn't work) Low
Sundog                 almost (FTL logo, load     low
                       for 30 seconds, CRASH!)


  As you can see, this emulator is more of a toy than a tool.  I think
they wrote it just to piss off Atari, 'cause, after all, only a better
computer can emulate a lesser one! >;)