<	 So I did a little search and found out thats it's possible to
<simulate TU58 tape on PC. I got impression that this allows also
<creating longer 'fake' tapes. This could work when the booting system
<doesn't care much, how much data has been read from tape and tries to
<read till end of tape is signaled or all is read. I searched for this
<emulator source code and couldn't find it. If someone has it and also
<has successfully used this program, let me know.

I haven't used it though I do remember seeing the source.  You can't fake 
bigger tapes as the other end (VAX) will not size tu58s larger.

<	Maybe putting together something, that is loadable from this
<TU58 tape and which implements something like netboot via tftp, could
<alse solve this? I would like to run NetBSD on VAX750/11 - it's also a
<great heat source, very handy at cold wintertime :-)

I think MOP boot is you only choice. or get a real tape.

<	If they have serial interface, then maybe there is a way to
<build a signal converter?

It's serial plus a handful of control signals, not a trivial task.  The SCSI 
version is a better shot.  Then you need a Unibus to TK50 interface to use 
it on the vax.

Allison