I have a pair of Pertec-branded circuit boards,
14" x 16"x, marked as follows:
PE WRITE
PC86V1
101387-01K
101388J
PE READ
101389-01J1
101383H1
My guess is that 'PE' is 'Phase Encoding'. IIRC that's the standard
used
for 1600 bpi tapes (800 bpi being NRZ).
So yes, I think they come from a 9-track tape drive or
controller/formatter. As to which particular drive, I haven't a clue.
-tony