On Monday, August 27, 2012 11:10:57 PM UTC-5, oli wrote: > > Hi, > > I was hoping for a SCSI adapter running from the Firewire 400 bus. > Haven't found one though. >
These folks used to sell them: <http://www.macgurus.com/store/ecom-prodshow/SCSIFR1SX.html> but they're out of stock and at $140 they weren't very affordable. Still, you might be able to extract a part number and/or product name and use that as a basis for your search. PCI chassis work because the PCI specification includes a device called a PCI-PCI bridge, which is a device which sits in one PCI slot and creates up to sixteen more slots downstream of itself. Using a PCI expansion chassis should not affect the PCI performance of your other slots, however, all the cards installed in the chassis will share whatever interrupt was available in the original slot. This can sometimes be a problem. Also, on the earlier PCI Macs there is a bug in Apple's implementation which does not properly handle PCI-PCI bridges. The result is that if you have a daisy chain of bridges, (one bridge in one of the "slots" of another bridge) and there is more than one PCI card in the "lowest" bridge's slots, the Mac will freeze up when firmware for the second card tries to load. This mainly comes up if you use an expansion chassis (or Umax J700 or S900) and install a USB/Firewire combo card, or one of the video cards that looks like two PCI devices to Open Firmware, or one of the SCSI cards (most of the dual ported cards) which looks like two PCI cards to firmware. Oh, and some of the ATA cards have the same issue. Essentially, many PCI cards have what amounts to a PCI-PCI Bridge on the card (USB/Firewire combo cards literally have a PCI-PCI Bridge chip on board). So when you install one of these cards in a slot downstream of another PCI-PCI bridge, e.g. in an expansion chassis, you're creating a chain of two bridges and Apple's bug rears it's ugly frozen head. The PCI specification allows for creating several levels of PCI-PCI Bridge, so the multi-level bridge things should work, but it doesn't (or didn't) in Apple machines. I don't know if Apple fixed this firmware bug in later machines, but it was awfully persistent in earlier machines. It didn't get noticed much because not that many folks use PCI expansion chassis (the lower 4 (2) PCI slots in the Umax S900 (J700) are an expansion chassis off of the third PCI slot) and in more recent machines, the video cards are no longer PCI, and USB and Firewire are built in, so that eliminated many of the PCI cards that have two PCI devices on board. There were two later revisions of the ROM in the x500 and x600 PCI Macs and neither one did diddly to address this bug. So, you may need to avoid most of the later Initio SCSI cards, as they're all dual ported cards, which look like two PCI devices. And the Adaptec 2940U2B has the same issue, IIRC, both the Adaptec and the Apple versions. Jeff Walther -- You received this message because you are a member of G-Group, 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] For more options, visit this group at http://groups.google.com/group/g3-5-list
