The program ATMITOPC.PRG is only meant to run on the PC
(under STEEM) to receive MIDI data from the ATARI ST to
create a Virtual MIDI device with the sound card of the PC 
for the case that you do not have an external MIDI device.

Thus, You can run the BWL software on an ST and use your PC
as a MIDI sound device.

Why?

Althought the BWL software for the PC runs with STEEM on a 
fast computer (333 mHz at least) good enough for Brain sessions, 
its timing accuracy is less stable than when runned on an Atari ST.
For scientific research, wherein one want an absolute stable Puls width, 
one should simply use the goody old ATART ST.

The reason for this is that Windows interrupts frequently.
This causes a regular timing error of 10 Ms (Milli seconds).
High frequencies or a short puls width on high frequencies significantally 
degradate the stability of the puls train. It does not matter how fast your 
computer gets because it is an operating system interrupt.

In contrast, on the Atari ST - with its simple non-multi tasking operating 
system in combination with the close-to-hardware programming of the BWL software 
does not have this problem at all.

Again:
This only should be taken into considaration when you like to do scientific 
research and do not want your results to be useless due to a 10 Ms puls train interference. 