From: utzoo!decvax!wivax!linus!genrad!wjh12!foxvax1!brunix!rayssd!dhb
Newsgroups: net.periphs
Title: Re: phase-encoded
Article-I.D.: rayssd.1089
Posted: Thu Apr 21 11:20:04 1983
Received: Mon Apr 25 20:46:08 1983
References: sii.270

NRZI (Non Return to Zero, I forget what the I stands for) and
phase-encoded are two methods of doing the physical recording
on the tape.  The difference has something to do with zero bits
but the complete definition escapes me at the moment (it's been
a while since I concerned myself with tape drive hardware
questions).  There is also another method called GCR (Group
Coded Recording) which is frequently used for 6250 BPI.
Anyway, I suggest you get ALL the hardware manuals if you want
to attempt to understand the difference between them.  It also
helps if you are a practicing electrical engineer.

	Dave Brierley, {decvax!brunix, foxvax1!brunix, allegra}!rayssd!dhb