On Jun 15, 2009, at 9:49 AM, insightinmind wrote:
> Funny ... the top of the Seagate drives say use Cable Select for its > Ultra ATA drive ... but one of Apple's docs says Cable Select won't > work for Ultra ATAs in the Quicksilver 2002 and other G4s ... and to > not use the Apple supplied cable ... The Apple cables from the B&W on are 80-wire/40-pin, and are configured for Cable Select so that the H-P/Compaq patented method of interrogating the drives may be used during startup. At all other times after startup, the Mac uses Master and Slave (or Master, alone). As a side note, the optical drives currently being made may be Ultra/ 33, but they require an Ultra/66 cable in order to exceed 8X writing. And, an Ultra/66 cable just happens to be 80-wire/40-pin. In G3 and G4 Macs, the optical drive is always Master. The way Apple laid-out the optical/zip cable on all models from the B&W on, the optical drive is always the last on the cable and must be Master. The Zip, if present, will be next-to-last and must be Slave. There is an unfortunate historical basis for this. In the first models which Apple made which employed ATA drives, the vendor which Apple selected for optical drives had a flaw which prevented the drives from being Slave. Somewhat similarly, the first Zip drives had a flaw which prevented them from being Master. Consequently, Apple adopted an optical:Master and Zip:Slave policy on that and subsequent models. The flaws were subsequently corrected by the drive manufacturers, but Apple did not change its policy. (In the Beige models, the flaw in the Zip drive was accommodated by installing a SCSI Zip, as the first generation Beige models did not support Slaves at all. The second and third generation Beige models finally had Slave support). The short cable which Apple supplies for hard drives is also configured for Cable Select, also for the reason of the H-P/Compaq patent. If replaced with a home-made 40-wire/40-pin cable, you will most likely have problems. If replaced with a known-good Apple short cable, or a common PC cable which is also Cable Select, you won't have problems. (Using great care, it is possible to salvage the connectors and cable from a PC 80-wire/40-pin cable and make the equivalent of an Apple short cable. You would retain the blue Host connector, and move the black and the gray Media connectors). The Apple long cable generally exceeds the maximum cable length, but Apple has tested the cable with drives and found that it is satisfactory under all conditions which it offers its products. It is probably OK, too, with customer-installed drives, particularly late- model ATA burners, such as Pioneer, and also late model ATA hard drives, such as the Ultra/100 drives from Seagate and others. The optical bus is usually Ultra/33, but it could be Ultra/66 on some models. Nevertheless, the optical cable is manufactured as if it was an Ultra/ 133 cable, using cable and connectors which are appropriate for Ultra/ 133. Of course, the limiting factor is the speed which the optical bus chip will operate, and that is Ultra/33 for most models, and Ultra/66 for some. But, using the H-P/Compaq patented method of interrogating the drives, the optical bus chip, the drives, and the interconnecting cable are all designed for automatically selecting the fastest mode which is appropriate for a specific drive. On an optical bus which is Ultra/66, the optical drive will usually be Ultra/33, whereas a hard drive which is installed in place of the Zip drive (which also was Ultra/33) will be Ultra/66 if the hard drive is Ultra/100 or faster. --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed Low End Mac's G3-5 List, a group for those using G3, G4, and G5 desktop Macs - with a particular focus on Power Macs. The list FAQ is at http://lowendmac.com/lists/g-list.shtml and our netiquette guide is at http://www.lowendmac.com/lists/netiquette.shtml To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/g3-5-list?hl=en Low End Mac RSS feed at feed://lowendmac.com/feed.xml -~----------~----~----~----~------~----~------~--~---
