Why Mac PCI video card cannot be used in PC

Discussion in 'Macintosh Computers' started by lbodnar, Feb 6, 2004.

  1. lbodnar macrumors regular

    Jan 5, 2004
    I have just now realised why exactly Mac PCI Video card would not work in PC.

    IMB PC and compatibles have BIOS ROM on the motherboard that contains a simple startup code to help the computer to initialise and boot into OS.
    After OS has booted it does not use BIOS anymore (well, MS-DOS does...)

    Traditionally BIOS recognises and supports only CGA and EGA video adaptors (they are about 20 years old :) ) Because of the vast variety of possible VGA, SVGA and other hardware PC standard uses mapping of an ISA or PCI board's ROM chip into memory address of CPU (somewhere between C000h and E000h). At the very early stage of booting CPU scans this address range and if it finds a card's "piggy-back" ROM (by looking for a specific signature), it passes the control over (e.g. simply CALL 0xD004h) to this card's ROM and expects that the card does its necessary init and returns control back (RETURN).

    Obviously Mac video card ROM contains anything else but x86 CPU instructions so the PC will simply choke up and system will never even be able to show its startup screen. Even though OS includes hardware-specific drivers in software the system will never reach that stage as it heavily relies on video system being operational from the very early stage of the boot process.

    Now if somebody would explain why PC cards would not work in Mac without reflashing? Is the above applies to Mac booting process as well?
  2. Lanbrown macrumors 6502a

    Mar 20, 2003
    Apple uses Open Firmware or IEEE 1275. Sun created it and Apple adopted it; it was taken to the IEEE and became a standard. No one else really adopted it. It is very powerful and flexible as well. Sun refers to it as Open Boot. In Sun land, one could use a PeeCee video card that used the same chipset as one Sun used. Some didn't have much success though. You would not get any display until the OS was loaded, as the PeeCee video card could not be initialized by OB. The code in the GPU could be such as to prevent it from working if it see OF or doesn't see the BIOS. You also have IRQ issues in a PeeCee, something that you don't have.
  3. IndyGopher macrumors 6502a


    Nov 3, 2001
    Indianapolis, IN
  4. werkmanatwerk macrumors newbie

    Feb 27, 2004
    PC cards on MAC

    I have never delt with video cards but I am being asked to VJ a rave and I need to use a PC (I cant use the 4 MACs I own) to run the software apps that are PC only.

    So I am looking at XFX GeForce FX 5950 Ultra, ATI Radeon 9800 Pro (256MB), and Nvidia GeForce FX 5900 Ultra. If I spend $400 on one of these, I want to be able to use it on my MAC after I am done using it on a PC. My question is simple, but the answer I am guessing from the above posts isn't... is this possible? Does it involve flashing the card? What does flashing mean/involve? Is this really dependent on more specific info? I will soon be running dual hardrives with OSX and OS9.
  5. superbovine macrumors 68030


    Nov 7, 2003
  6. Vlade macrumors 6502a


    Feb 2, 2003
    Meadville, PA
    Basically the answer is No, not with those cards. The only cards that you can flash to mac are the Geforce2MX and Radeon 8500, with some luck on the PCI version of the radeon 7500 and Geforce 4MX.

    Also, between those cards, get a Radeon 9800 Ultra with 128 megs of ram, 256 is absolutely useless even for games like doom 3 and half life 2. The nvidia cards aren't as good for the money, or in general really.
  7. kingtj macrumors 68020

    Oct 23, 2003
    Brunswick, MD
    Flashing a Radeon 9800 for Mac use

    Actually, I think it *is* technically possible to flash an ATI Radeon 9800 Pro card from a PC version to a Mac version!

    In the past, ATI made some effort to prevent this from happening, by purposely using flash chips soldered onto the 2 different "flavors" of a given card that had different storage capacities. (Therefore, your "Mac" firmware might not all fit in the flash chip on the PC version of the same card.)

    As best as I can tell, though, this practice hasn't continued with the 9800 Pro. ATI orginially announced on their own web site that both PC and Mac versions of this card would sell for the exact same retail price. (So they weren't making extra $'s off Mac users anymore with this particular card, anyway.)

    The problem is, though, the Mac versions of the 9800 Pro's aren't stocked locally at a single store in my city - and the few mail order houses that do sell them seem to stick real close to full list price. (By contrast, the discount stores in town carrying the ATI 9800 Pro PC edition have plenty in stock, and seem to cut prices on them significantly below list.)

    So I started investigating re-flashing a PC card for Mac. My biggest "stumbling block" seems to just be getting ahold of a copy of the Mac firmware itself. If you visit http://www.3dchipset.com/bios/index.php -- you'll see that they have several PC utilities for re-flashing (and even editing existing flash ROMs) on these cards. They also have several flash ROM images to download, but all seem to be for the PC versions of the cards.

    I think if you put a PC edition of a 9800 Pro in a PC, along with a secondary PCI video card (so you could see what you're doing while you try to flash the 9800 Pro card that's in there!), you could use one of these tools to turn it into a Mac edition. You just need the correct firmware image.

    Maybe someone here who already has a 9800 Pro Mac edition could try moving their card over to a PC and using one of these utilities to dump their fimrware to an image file for us??

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