First, to the person asking for a quick speck sheet for the all the various mac models... I found mactracker to be more useful than my cars glove box book. mactracker comes as a control strip module. A simple click and you have a quick reference for original release specs on any mac computer,apple printer, monitor,etc. It's also self updateable. If memory serves me right, I think I DL'd my copy from puremac.com one night. of course you could try mactracker.com ???
Now the SCSI termination issue. This is getting humorous, and I think there is a great deal of confusion going on here with this one. If my memory serves me correctly, ALL INTERNAL "SCSI" Hard Drives need to be terminated (or "should" be). Actual physical postion of a SCSI drive on the INTERNAL ribbon doesn't make a difference for INTERNAL SCSI. All SCSI devices internal or external need to be properly addressed. Only the main INTERNAL SCSI HD can get away without jumpers for addressing, since it will default to id#0. The factory default has always been; (main) HD #0, CD #3,. EXTERNAL SCSI devices are different. Only the last device on an EXTERNAL SCSI chain CAN and MUST be terminated if you want everything on the EXTERNAL chain to operate properly. ALL external devices must be addressed properly also. the address # does not necessarily have to corspond to the devices actual physical location on the chain, they all just need different address #'s. IDE/ATA drives and busses are MUCH DIFFERENT and I think this is where some of the confusion is comming from. On an Internal IDE bus, the "MAIN DRIVE" MUST be the LAST device on the ribbon AND addressed as either SINGLE or DUAL MASTER if another device is present (2nd HD, CD ROM?,ZIP,etc.) Any second device on the ribbon MUST be addressed as DUAL SLAVE. Some newer IDE drives/computers/ribbons also allow for what is know as "cable select" that is, the last drive on the ribbon will automatically be selected as the "master". Cable select requires a specific ribbon and usally has a blue colored connector as the last connector on the ribbon. I don't believe any pre G3 macs with IDE drives have this functionability. The BIG why? on the SCSI: ie; BASIC ELECTRICAL 101. INTERNAL SCSI Chains are in effect what is known as a "series/parallel" circuit. that is, one big loop with a bunch of little branches leading off the main loop. Each individual branch need a return point for the current, hence the "termination". EXTERNAL SCSI chains are series circuits. One big loop only. Hence, only the last device can and does needs to be terminated or else electrical current will stop flowing. Because of the way external devices are made, if the device is shut off, current mearly flows through the connectors on the back and onto the next device on the chain. If the last device is not terminated, current stops flowing. If any other device is terminated before the last device, current will turn around and return to it's source from that point of termination. Anything else on the chain after termination will fail to be seen. Most EXTERNAL devices can be terminated either externally or internally. As far a proper jumper locations for termination and addressing, always consult the manufacturer's website if in doubt. Although, most scsi drives do have a little diagram on them. Sure beats having to open the case and remount that drive a dozen times. Of course, I've been known to be a glutton for punishment myself..... Ok, I'm pretty sure that was way more than anyone cared for.... *****SCSI**************************SMALL***COMPUTER***SYSTEMS***INTERFACE*** ____________________________________________________________________________ -- PCI-PowerMacs is sponsored by <http://lowendmac.com/> and... Small Dog Electronics http://www.smalldog.com | Refurbished Drives | -- Sonnet & PowerLogix Upgrades - start at $169 | & CDRWs on Sale! | Support Low End Mac <http://lowendmac.com/lists/support.html> PCI-PowerMacs list info: <http://lowendmac.com/lists/pci-powermacs.shtml> --> AOL users, remove "mailto:"; Send list messages to: <mailto:[EMAIL PROTECTED]> To unsubscribe, email: <mailto:[EMAIL PROTECTED]> For digest mode, email: <mailto:[EMAIL PROTECTED]> Subscription questions: <mailto:[EMAIL PROTECTED]> Archive:<http://www.mail-archive.com/pci-powermacs%40mail.maclaunch.com/> Using a Mac? Free email & more at Applelinks! http://www.applelinks.com
