At 19:57 -0400 09/23/2004, Pastor Mac wrote:
Both responses were about the Sonnet cards which were specifically marketed to Mac people. Take a look at this page: http://www.newegg.com/app/ViewProduct.asp?submit=list&catalog=410&DEPA=1
There's a few cheap cards there for 25 bucks or so. What I want to know is if those cards will work in a Mac, especially a S900 for OS X.
Answering your specific question (IIRC the question), IDE cards need to be built specifically for the Mac in order to work on the Mac. IDE cards for the PC will not work in a Mac--although a few models might work under OSX but not support booting off of devices connected to them. And a rarity would be a CMD64 (I think that's the model) chipset based IDE card in a Blue & White which should work even in the PC version, because that's the chipset Apple used (in the B&W) for the on-board IDE, so support is already in the Blue & White's firmware.
Going from the general to the specific:
All PCI cards require drivers in order for your computer to know how to communicate with the PCI card. Drivers are specific to the PCI card and to the platform on which the PCI card is used. So Mac drivers don't work in PCs and PC drivers don't work in Macs. And drivers for ATI video cards don't work on nVidia video cards. Etc.
Drivers can be stored in the operating system as extensions (or whatever they use in OSX), or they can be stored on the PCI card itself, or they can be stored in the ROM (firmware) of the computer.
Drivers that are part of the operating system do not load until the operating system loads that specific extension. So, e.g., drivers for firewire cards don't load until the Mac OS loads the drivers/extensions for firewire. Until that happens, Firewire devices are unusable by your Mac because it has no way to communicate with them. It doesn't know how to talk to them until the driver loads.
That's why you can't boot from Firewire devices. (We'll get to newer machines, which can boot from Firewire in a few paragraphs.)
Drivers that are stored on the PCI card are stored in a non-volatile memory chip on the card. Non-volatile just means that the contents don't go away when the power goes off. These chips are EPROMs, EEPROMs or Flash chips. The fine distinctions between them don't matter for this discussion.
The Mac interrogates the PCI cards at boot time and loads any drivers that it finds stored on the PCI cards. There are very specific standards about how to let the Mac know that a PCI card has a driver on board. As you might imagine, that early in the boot process, the Mac isn't very smart yet because it hasn't loaded much software telling it how to do things.
So PCI cards with drivers stored on the card tell the Mac how to talk to themselves at boot time. So the Mac learns how to talk to this type of card very early in the boot process and long before the OS starts to load. This type of card includes video cards, SCSI cards (except the Adaptec 2906) and IDE/ATA cards.
The third place drivers might be found is in the host Mac's firmware. Macs have IO devices on board and the Mac must know how to communicate with them. Some built-in IO devices are needed at boot time, such as SCSI, IDE and video devices, so drivers for these devices are included in the firmware (ROM) of the Macintosh. For example, there is an ATI Rage II or Rage Pro driver in the ROM of the Beige G3 because the Beige has an ATI Rage chip on the motherboard.
There are also some hybrids and most of those are video cards. Video drivers are huge and would not conveniently (affordably) fit in storage on the PCI card. So video cards contain a simple driver on the card which gets the card going in a low-performance mode and then depend on the Mac OS to later load the high performance drivers that give the card its ooomph.
One implication of this hybrid situation is that some video cards for PCs might work on a Mac depending on how extensive the OS-loaded driver is. In this situation the user would see a video card that doesn't work at all when the Mac first boots up. The screen would stay dark as the Mac loads the OS. Then when the Mac loads the extensions for the video card, the video card would suddenly spring to life. This isn't the only situation that could cause those symptoms, but it is one.
The above also describes the situation for some SCSI cards in OSX. OSX apparently contains drivers for a few models of PCI card. So those cards don't work at boot time (if they don't have an OSX driver stored on the PCI card) but once OSX loads its software drivers for those cards they start to work.
In the case of Firewire cards, older Macs such as the ones relevant to this list do not have Firewire drivers in their firmware/ROM. And Firewire cards do not have drivers stored on the card. So firewire cards are not bootable on our older machines. However, at some point, Apple started putting the drivers for Firewire in the ROM/firmware of the Mac and those newer Macs can boot from Firewire devices. If someone were to build a firewire card with Mac drivers on the card, then it would be bootable in our older machines.
The same information applies to USB cards and most Ethernet cards as well as to Firewire cards.
In many cases it is possible to take a PC version of a card and replace the driver stored on the card with a Mac version of the driver. This is what's done to convert PC destined Radeon 7000s into the Mac version.
Very few IDE/ATA cards are susceptible to this type of conversion.
Jeff Walther
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