Your computer is probably not seeing them because one is not terminated. Whatever drive is physically at the end of the ribbon cable (SCSI bus), must be terminated. The reason the end device is terminated, is to pull the voltage all the way to the end of the ribbon cable. If more than one device has termination, it can pull too much voltage and ruin the SCSI bus. If they are LVD drives then you will need LVD termination.
Second, each device on the ribbon cable (SCSI bus) must have a unique ID. Normally the boot drive will be ID 0 (no jumpers on ID0, ID1, ID2 or ID3). The CD rom drive is usually ID 3 which would be jumpers on ID0 & ID1. The computer is usually ID7, and there are no jumpers involved. You can get jumpers at your local computer store that deals with SCSI drives. The tab on the jumpers is so that you can get your itty bitty fingers on them. The ID jumper setup goes like this: SCSI ID# Pin ID# (on drive) ID0 No jumpers ID1 Jumper on ID0 ID2 Jumper on ID1 ID3 Jumpers on ID0 & ID1 ID4 Jumper on ID2 ID5 Jumpers on ID0 & ID2 ID6 Jumpers on ID1 & ID2 ID7 Jumpers on ID0, ID1 & ID2 ID8 through ID15 is repeated but with a jumper on ID3 as well (you would use this only if you had a scsi card that recognized ID's 8 through 15) HTH STeve << I just picked up two brand new 50-pin IBM SCSI 4GB hard drives. They came with a jumper on the pins designed "autostart" -- no other jumpers on the pins. When I plugged the drives in, my 7500 doesn't see them in Disk Setup, even though they clearly "autostart" when the computer starts up. BTW, I'm running 9.1. Am I missing something? The whole pin & jumper scene has always confused me. Do I need a jumper on the ID0, ID1, ID2 or ID3 pins? Where do I get jumpers -- if only one comes with the HD, where do I get more? Also, the jumper that came with the HDs has a little tab sticking out of it -- is that for convenience so you can grab it better or does it have another function I'm missing? >> -- 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:pci-powermacs@;mail.maclaunch.com> To unsubscribe, email: <mailto:pci-powermacs-off@;mail.maclaunch.com> For digest mode, email: <mailto:pci-powermacs-digest@;mail.maclaunch.com> Subscription questions: <mailto:listmom@;lowendmac.com> Archive:<http://www.mail-archive.com/pci-powermacs%40mail.maclaunch.com/> Using a Mac? Free email & more at Applelinks! http://www.applelinks.com
