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Power Mac G4 MDD and the USB 2.0 chip
Posted by: Dandu on 2026-05-27 10:12:31 I have found a Power Mac near me, i will try to buy it.
Posted by: chriscarruthers on 2026-05-28 01:10:00 I wonder if perhaps the chip is there for the AirPort Extreme + Bluetooth? That's another distinguishing feature of the FW800s compared to all other G4s.
Posted by: greystash on 2026-05-28 02:41:39 Any other side effects of downgrading? Because if not, it almost seems like a no-brainer as you gain OS9 support. I have a downgraded FW800, I think the only downside was that the FW800 ports were recognised as FW400 (maybe only on OS9, i can't remember), but I never actually tested that. It's been running nicely for many years without issue.
Posted by: croissantking on 2026-05-28 05:54:18 I wonder if perhaps the chip is there for the AirPort Extreme + Bluetooth? That's another distinguishing feature of the FW800s compared to all other G4s. Oh they probably needed an extra internal USB port for Bluetooth. AirPort Extreme would be a PCI device. I have a downgraded FW800, I think the only downside was that the FW800 ports were recognised as FW400 (maybe only on OS9, i can't remember), but I never actually tested that. It's been running nicely for many years without issue. Would be good to check it FW800 still works under Mac OS X (and AirPort Extreme/BT, if you have those).
Posted by: greystash on 2026-05-28 14:58:26 Would be good to check it FW800 still works under Mac OS X (and AirPort Extreme/BT, if you have those). What's the best way to test speeds? The only FireWire device I have is an iPod which I could try this weekend. The AirPort Extreme works, and will also test BT
Posted by: croissantking on 2026-05-28 15:27:17 What's the best way to test speeds? The only FireWire device I have is an iPod which I could try this weekend. The AirPort Extreme works, and will also test BT If you don’t have a fw800 device you won’t be able to test if it’s working at full speed. Maybe you could see what it reports in system profiler about the bus itself. I guess there should be two buses?
Posted by: joevt on 2026-05-28 15:29:11 What's the best way to test speeds? The only FireWire device I have is an iPod which I could try this weekend. The AirPort Extreme works, and will also test BT The iPod only has FireWire 400. You'll want a Hard Drive enclosure that supports FireWire 800 to test the speed of the FireWire 800 port. If you had a second Mac with FireWire 800, you could try FireWire 800 networking. Try `iperf` 2 for PowerPC Mac OS X? You could also try FireWire target disk mode - but I don't think FireWire from an Open Firmware host will be as fast. This thread shows a handful of disk benchmark apps. https://68kmla.org/bb/threads/lets-see-your-best-disk-speeds-ppc-68k.49268 Here's a download link for a PowerPC version of "AJA KONA System Test": https://www.aja.com/support/legacy/kona-3 Is there a better link for AJA System Test for PowerPC?
Posted by: greystash on 2026-05-31 18:39:44 After taking screenshots of System Profiler on two separate MDDs, I realised I swapped the downgraded logic board out a while back when troubleshooting stability issues (it was the PSU). When I get some more time I'll put it in a working machine and try again, unless anyone else is game to try the downgrade
Posted by: Matias_ on 2026-06-03 02:42:40 See also: Mac Os 9 booting on: G4 Tower MDD FW800 (Detailed Posts) Mac Os 9 booting on: G4 Tower MDD FW800 (Detailed Posts) macos9lives.com USB 2.0 in some Power Mac G4 MDDs? UPDATE: Apple Replies USB 2.0 in some Power Mac G4 MDDs? UPDATE: Apple Replies web.archive.org
Posted by: Matias_ on 2026-06-03 07:16:05 Alright so I did some testing on my 1.42 GHz DP FW800 MDD. None of the OrangeUSB kexts in this thread did anything for me on OS X, my flash drive kept showing up as 12Mbps in system profiler. But I was able to confirm USB 2.0 functionality out of the box on Linux.
Posted by: croissantking on 2026-06-03 07:48:43 Alright so I did some testing on my 1.42 GHz DP FW800 MDD. None of the OrangeUSB kexts in this thread did anything for me on OS X, my flash drive kept showing up as 12Mbps in system profiler. But I was able to confirm USB 2.0 functionality out of the box on Linux. So the artificial firmware limit to USB 1.1 speeds doesn't apply to other operating systems, interesting. This suggests a patch to enable 2.0 speeds could come in the form of either a firmware mod (similar to downgrading to the FW400 firmware) or a Mac OS mod.
Posted by: Dandu on 2026-06-07 07:10:06 So. I have tried with a Linux Live CD, and the NEC chip was usable with the original ROM. After that, i have flashed the old ROM, and it works : with Mac OS X Tiger, the USB 2.0 is working,no problem with a USB flash drive. There is a weird things : with the original ROM, Mac OS X list only the NEC chipset (limited at USB 1.1). With the old ROM, there is the NEC chipset and the Key Largo controller on the list (but not usable)
Posted by: Dandu on 2026-06-09 10:55:32 I have write a thing about that : https://www.journaldulapin.com/2026/06/09/powermac-g4-usb/
Posted by: croissantking on 2026-06-09 11:34:19 I am really curious if the FW800 firmware update was literally just to block OS9 booting and USB 2.0...
Posted by: CuriosTiger on 2026-06-23 08:56:51 I am really curious if the FW800 firmware update was literally just to block OS9 booting and USB 2.0... It really is starting to feel that way based on the info in this thread. I've been trying to build an FW400 MDD, but I may just reassemble my FW800 MDD and try to firmware-"downgrade" it.
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