Path: utzoo!utgpu!watmath!clyde!bellcore!rutgers!mailrus!tut.cis.ohio-state.edu!cs.utexas.edu!sm.unisys.com!csun!polyslo!dorourke From: dorourke@polyslo.CalPoly.EDU (David M. O'Rourke) Newsgroups: comp.sys.mac Subject: Re: Mac Plus ?? Message-ID: <6640@polyslo.CalPoly.EDU> Date: 10 Dec 88 03:12:25 GMT References: <508NETOPRRW@NCSUVM> <771@husc6.harvard.edu> <401920b8.1285f@maize.engin.umich.edu> <1282@mace.cc.purdue.edu> <401a38a0.129dc@b <1136@paris.ics.uci.edu> Reply-To: dorourke@polyslo.CalPoly.EDU (David M. O'Rourke) Organization: Cal Poly State University -- San Luis Obispo Lines: 27 In article <1136@paris.ics.uci.edu> Andrew Kwan writes: >rotation speed and the number of sectors per track. It is not >dependent on the number of turns it has to make - sector accesses do >not require having to wait until the track makes a full turn to get to >the next sector to be accessed, only for the next one or two sectors >to pass (to get to the one you want). Assuming that you want to read all the sectors in a track, which happens quite often when reading a contiguous {sp??} sequence of sectors then the interleave does make a difference!! The SE can read a whole track of information in two disk rotations {latency time}, while it would take the plus at a 3:1 interleave 3 disk rotations to read the same information. ie. approx. 50% longer on the plus for the same about of information. I think your basic premise is correct if you want to only read one sector, but this rarely happens. I believe if you think disk accessing through just a little farther than you did in your previous posting. When accessing several sectors in a row, latency can make a significant diffence is access time and effective throughput. If interleave didn't make any difference then what point would there be in having it. :-) -- David M. O'Rourke dorourke@polyslo.calpoly.edu "If it doesn't do Windows, then it's not a computer!!!" Disclaimer: I don't represent the school. All opinions are mine!