On Mar 31, 2020, at 5:16 PM, Thomas DeBellis
<tommytimesharing at gmail.com> wrote:
 
 How did you format the tape?  A TU55 DECtape could be formatted, but I thought that the
cassette tapes had to be bought preformated. 
You may be thinking TU58 here.  Those are block-addressable like TU56, just slow and
unreliable.
TA11 is essentially a magtape on an audio casette medium.  Just like 7 or 9-track tape,
there is no formatting, and you can only write sequentially.  See the Handbook, it
describes it clearly enough.
	paul