Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!texbell!merch!cpe!adaptex!neese
From: neese@adaptex.UUCP
Newsgroups: comp.sys.ibm.pc
Subject: Re: Charity
Message-ID: <6100020@adaptex>
Date: 24 Oct 89 14:30:00 GMT
References: <13091@boulder.Colorado.EDU>
Lines: 26
Nf-ID: #R:boulder.Colorado.EDU:13091:adaptex:6100020:000:1063
Nf-From: adaptex.UUCP!neese    Oct 24 09:30:00 1989


>1. Briefly, what do the following abbreviations mean:
>
>  	RLL
>	MFM
>	ESDI
>	SCSI

RLL and MFM refer to data encoding schemes.  That is how the data is actually
written to the disk.  ESDI and SCSI refer to interface specifications.  ESDI
and SCSI use RLL for most encoding schemes.  There is also a variant of the
RLL encoding scheme that is used with SCSI only.  It is called ZBR.  This
encoding scheme actually creates zones on the drive that have different
numbers of sectors in each zone.  This is done to get the most capacity
possible out of a drive.  For instance, the outer zones (or tracks) of a
drive can hold more data than the inner zones (tracks).  SO the HD
builders put as many as 93 sectors on the out zones (tracks) and as few as
32 sectors on the inner zones (tracks).  You can do this with SCSI as SCSI
presents a logical interface to the user, all other interfaces, in the AT
world, use a physical interface.


			Roy Neese
			Adaptec Central Field Applications Engineer
			UUCP @ {texbell,attctc}!cpe!adaptex!neese
				merch!adaptex!neese