On Oct 5, 2008, at 1:08 PM, Dana Collins wrote:
> I was thinking more of drives connected to 3rd party controller cards > (like my Siig ATA-133 card) i.e. a drive not connected to the host > busses found on the motherboard. The same rules apply. The PCI cards simply present a SCSI Manager 4.3 software interface image to the Mac, and then translates that to equivalent ATA commands. If a PCI card (which usually has two 40-pin connectors) has both connectors empty, then the host sees no bus. Once a connector and its attached cable has at least one drive attached, the host sees a SCSI bus and its attached drive or drives. The limitation ... at least on the old six-slot machines ... was four such cards [ * ] . [ * ] For example, a 9500 or 9600, which has six PCI slots, five of them usable for expansion, has these SCSI buses, in the maximum configuration case (assuming PCI cards for all except the mobo's SCSI buses): SCSI Bus 0 (10 MB/sec -- primary 50 pin internal connector), IDs 0 through 6, with the machine's basic hard drive being ID 0 and the machine's basic CD-ROM being ID 3, thereby leaving IDs 1, 2, 4, 5 and 6 available SCSI Bus 1 (5 MB/sec -- external 25 pin connector and secondary 50 pin internal connector), IDs 0 through 6, normally not used for basic drives, but intended for external drives SCSI Bus 2 (speed dependent upon the card, but in the aggregate the throughput is about 40 MB/sec) ID 0 and 1 on first connector, ID 2 and 3 on second connector [ first PCI card ] SCSI Bus 3 (speed dependent upon the card, but in the aggregate the throughput is about 40 MB/sec) ID 0 and 1 on first connector, ID 2 and 3 on second connector [ second PCI card ] SCSI Bus 4 (speed dependent upon the card, but in the aggregate the throughput is about 40 MB/sec) ID 0 and 1 on first connector, ID 2 and 3 on second connector [ third PCI card ] SCSI Bus 5 (speed dependent upon the card, but in the aggregate the throughput is about 40 MB/sec) ID 0 and 1 on first connector, ID 2 and 3 on second connector [ fourth and last PCI card ] The machine does not care if there are three such cards on the highest-numbered slots (which have its own bus controller) and one on the lowest-numbered slots (which shares its bus controller with the video card) or if there are two such cards on each bus controller. The machine will hang in Power-On System Test if a fifth PCI ATA card is installed. --~--~---------~--~----~------------~-------~--~----~ 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 -~----------~----~----~----~------~----~------~--~---
