Path: utzoo!attcan!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!wuarchive!zaphod.mps.ohio-state.edu!van-bc! From: lphillips@lpami.wimsey.bc.ca (Larry Phillips) Newsgroups: comp.sys.amiga.hardware Subject: Re: hard drive controller definition; 14mhz motorola chip Message-ID: <2303@lpami.wimsey.bc.ca> Date: 1 Dec 90 19:30:01 GMT Lines: 33 Return-Path: To: van-bc!rnews In , ben@epmooch.UUCP (Rev. Ben A. Mesander) writes: >>In article <1990Nov29.185824.1990@sbcs.sunysb.edu> dtiberio@libws3.ic.sunysb.edu (David Tiberio) writes: >>What is a SCSI controller? >> >>It usually handles 8 hard drives. > >Almost. The SCSI bus allows 8 devices. Since the controller is one device on >the bus, it can only have 7 drives hooked to it. There are allowances for >extending this via having several devices hooked to different logical units >on a single SCSI device, but these are usually not used. Pong! (the sound of the puck hitting the post) Close. The SCSI bus allows 8 devices. Since the controller is one device, it can have only 7 other _devices_ hooked to it. Drives with embedded controllers can usually only handle the single drive they are part of, but there are _many_ controllers that will handle more than one logical unit. Some will handle two, some will handle 8. A very few will handle more (there is provision for up to 256 drives per controller). Don't know what you mean by 'usually not used'. Of the four controllers attached to my 3000, two of them are embedded in drives, with no provision for adding more drives, and the other two allow 2 drives per controller. -larry -- The only things to survive a nuclear war will be cockroaches and IBM PCs. +-----------------------------------------------------------------------+ | // Larry Phillips | | \X/ lphillips@lpami.wimsey.bc.ca -or- uunet!van-bc!lpami!lphillips | | COMPUSERVE: 76703,4322 -or- 76703.4322@compuserve.com | +-----------------------------------------------------------------------+