That seems to me like it would be the trickiest part.
The TU58 schematic appears to indicate that there are
I think so. Of course you could cheat by making it a read-only tape. But I don't like
that.
separate erase head gaps (not on a separate head like
in audio cassette drives), so maybe those could be
I am pretty sure there is just one physical head on the TU58 drive chassis. So if there is
a separate erase
field, it is a second gap in that head.
monitored to detect when a track is being written? Of
course, that probably means that a custom 4-gap head
would need to be made with gaps matching the two read/write and two erase gaps (and a
concave surface,
too, rather than recycling some audio tape head with suitable geometry to line up with
just the read/write gaps.
Ouch. Good luck in getting that, and even more luck in getting it positioned properly!
-tony