ATA-133 Backwards Compatibility with ATA-100/66 Buses?

Discussion in 'Computers' started by Ted Todorov, Mar 15, 2004.

  1. Ted Todorov

    Ted Todorov Cinematographer

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    I have a PowerMac DP-G4 1.25GHz, FW800, running OS X 10.3. I would like to install an internal 250GB internal ATA HD. I was looking at this one: MAXTOR L01P250, an ATA-133 HD.

    My question is, are ATA-133 (or SATA) drives backwards compatible to the Mac's ATA-100 &/or ATA-66 buses?

    I am not specifically attached to the above model -- my requirements are a reliable 250GB, 7200RPM ATA drive in the $200 range.

    Any and all advice would be greatly appreciated.

    Thanks,
    Ted

    P.S. Outpost says:
    That may be true, but just for older PowerMac models?? (The Apple store advertises G4 PMs with 160GB drives and no word of a PCI card). If it does turn out to be true, I'd be inclined to get a SATA card & drive.
     
  2. Keith Mickunas

    Keith Mickunas Cinematographer

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    If I remember right, ATA-100 can only handle a max of 137GB. It's a shortcoming of the protocol.

    The G4's being sold now may include ATA-133 built in, so they wouldn't require an add-on card. My knowledge is specific to PCs though, but I'm betting it's not going to work. That being said, the card shouldn't be too much money, I got a PC version for $20 to $30.
     
  3. Erik*R

    Erik*R Agent

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    its the the ATA bus speed that matters (33-66-100-133) its the controller. Some PC bios/ATA controllers cant handle more than 137GB drives.

    With Macs ive put a 200gig into a G4 before with no trouble. Shrug.
     
  4. Ken Chan

    Ken Chan Producer

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    A Serial ATA drive wouldn't work, because the connectors are different. But an ATA-133 drive should ratchet down as needed. And frankly, you might not notice a difference until you get down to ATA-33.

    Macs have supported the 48-bit LBA needed to address large drives for a while.
     
  5. Ted Todorov

    Ted Todorov Cinematographer

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    Thanks, Ken! This is just the info I was looking for.

    Ted
     
  6. Ted Todorov

    Ted Todorov Cinematographer

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    If anyone cares, I hooked up the 250GB Maxtor drive to the ATA-66* bus this morning and it works fine, with the full size available.

    *I remember reading somewhere that you get better performance by having one HD each on the ATA-100 & the ATA-66 bus than two on the ATA-100 bus.

    Ted
     
  7. Ken Chan

    Ken Chan Producer

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    Makes sense. You can't access the master and slave at the same time. As I said, you probably wouldn't notice any real performance issues until you got down to ATA-33, because most drives can't quite fill the 66 MB/s pipe anyway. ATA-133 and ATA-100 are overkill unless you have a RAID. (You do get full speed reading from the drive buffer, but since those are typically at most 8MB, those get flushed out in a fraction of a second, and then you're left with the drive's sustained read/write speeds.)
     

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