Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!mnetor!seismo!rochester!pt.cs.cmu.edu!cad.cs.cmu.edu!ralf From: ralf@cad.cs.cmu.edu (Ralf Brown) Newsgroups: comp.sys.ibm.pc,comp.periphs Subject: Re: Lot's of questions Message-ID: <1029@cad.cs.cmu.edu> Date: Sat, 3-Jan-87 23:24:07 EST Article-I.D.: cad.1029 Posted: Sat Jan 3 23:24:07 1987 Date-Received: Sun, 4-Jan-87 03:44:30 EST References: <9073FIB@PSUVM> <2750@osu-eddie.UUCP> <434@catnip.UUCP> <551@brl-sem.ARPA> Organization: Carnegie-Mellon University, CS/RI Lines: 31 Summary: Bernoulli Box heads *never* touch the media Xref: mnetor comp.sys.ibm.pc:775 comp.periphs:91 In article <551@brl-sem.ARPA> ron@brl-sem.ARPA (Ron Natalie) writes: >In article <434@catnip.UUCP>, ben@catnip.UUCP (Bennett Broder) writes: >> The reason that Bernoulli boxes can't suffer from head crashes is because >> the r/w head always contacts the media, just like a floppy disk. >Wrong, the bernoulli box is immune from head crashes because it the heads >are designed to be able to hit the media, but they are not always in contact >with the media. They achieve their faster turning rates over floppies by >forcing air under the heads. Wrong again: The Bernoulli Box is so named because it uses the Bernoulli effect, in which a rapidly moving stream of fluid (either liquid or gas) experiences a pressure decrease. The BB can't have a head crash, because in normal operation, the flexible media is pulled toward the head by the Bernoulli effect on the air moving between the head and the disk surface (this is the opposite of hard disks, in which the heads are shaped so that are flowing under them lifts the heads off the disk). If anything interrupts that airflow, such as a piece of dirt, the Bernoulli effect is lost, the media is no longer pulled toward the heads, and the media is now safely out of harm's way. THE HEAD NEVER TOUCHES THE DISK SURFACE--if it did, the Bernoulli effect would immediately be lost, again moving the disk surface away from the head. -- +=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=+ | ARPA: RALF@B.GP.CS.CMU.EDU "Teaching COBOL ought to be | | AT&T: (412) 268-3053 (school) regarded as a criminal act" | | Snail: Ralf Brown --- Edsger Dijkstra | | Computer Science Department | | Carnegie-Mellon University DISCLAIMER? Who ever said I claimed | | Pittsburgh, PA 15213 anything? | +=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=+