Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!uunet!pilchuck!amc-gw!thebes!polari!lampi From: lampi@polari.UUCP (Michael Lampi) Newsgroups: comp.periphs.scsi Subject: Re: Wren-V Parity jumper Summary: Many host adapters use parity on SCSI signals Keywords: SCSI, parity Message-ID: <2379@polari.UUCP> Date: 15 Aug 90 17:23:36 GMT References: <6399@uklirb.informatik.uni-kl.de> Distribution: comp Organization: MDL Corporation, Bellevue, WA (206) 643-7333 Lines: 23 In article <6399@uklirb.informatik.uni-kl.de> kirchner@informatik.uni-kl.de (Reinhard Kirchner) writes: >From article , by rdh@sli.com (Robert D. Houk): >> As I was replacing one of our Wren-V disks yesterday, going through the >> jumpers, I was reminded of a puzzle: What is the purpose of the Parity >> Jumper? ....[rest deleted for brevity] >So I phoned the distributor and they told me, the parity on the cable >is enabled. So it may be of use if there is a host adapter which generates >and checks parity on the cable, but I think most do not. They don't >have jumpers for this ! > Many host adapters and host systems support parity on the SCSI bus, including Apollo, Adaptec, Western Digital and others. Considering that the only means of detecting transmission errors in a non-parity checking system is by verifying data read or written to a peripheral through some sort of error- correcting code which would tie up more storage space and slow things down immensely, parity is a cheap and easy way of reducing the possibility of errors. Of course, if you don't mind 'slightly' incorrect data, then you don't need error checking :-) ! Michael Lampi