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View Full Version : 7500 HD installing - ID, termination help



01-29-2001, 07:04 PM
Guru friends

I am just not understanding this ID and termination. I need to move 2 drives around and install a new hard drive. I started this a month ago but have been out of action. I am back and am really ready to learn (really I am about to pay someone - ouch) I need to get these hard drives moved and installed. http://macgurus.com/infopop/emoticons/icon_redface.gif

I took a 1.2 gig from my 7200 and put it in a 7500 machine I am using now (I bought the 7500 with a XLR8 G3 upgrade). Dumb luck must have been with me. It is working fine (10-12 days) as the start up drive and has all my stuff on it. Both the 1.2 gig from the 7200 and the 1 gig that was in the 7500 are working.

Both drives are running 8.6.

What are the "pro's and con's" to having system software on both drives?

I tried putting a drive from another 7500 in it and it would not reconize it.

I have read enough to understand most of whats going on. With one big exception - How to actually do it. http://www.macgurus.com/ubb/confused.gif

Does the "Drive Setup" on my OS 8.5 CD Disk help or assist me?

Start me out again......

Thanks again
Randy

magician
01-29-2001, 07:17 PM
randy, if you look at the drives, you will see that very often there is a legend explaining the use of the drive pins on the top, or elsewhere on the drive. There are often very small abbreviations next to the pins, as well.

The ones that matter are those for addressing, typically marked 0,1,2, or E1, E2, E3, or something like that. Depending on the drive, these pins can be either on the front of the drive, or underneath it. These are addressing pins.

Each drive on a bus, in fact, each device, must have a different address. Boot drives are typically addressed at ID0, which corresponds to NO jumpers on any address pins. Placing a jumper over the 0-pins, meaning the top pin and the lower pin, addresses a drive at ID1. Using these two addresses is usually adequate for installing a pair of drives inside a machine.

the other pins that matter are marked TE and TP. TE stands for Termination Enable. If the drive is the last drive on the bus, that is, if you trace your ribbon cable from the logic board to the very last device, in order, on the cable, that drive, and only that drive, should have termination enabled with a jumper on the TE pins. No other devices on the same bus, meaning the same cable, should have a jumper on their TE pins. Only one device, the last physical device, is terminated.

the TP pins are another matter. This can get somewhat complicated, but you want to consult the documentation for your device so you can set the drive to draw Termination Power FROM the bus. You may need to search for your drive part number on the website of the manufacturer that built it to find this information.

hope this helps!