Adding USB-C (Kinda) To A PowerMac G4

For those who’ve never bitten the Apple, the PowerMac G4 was a blue-tinted desktop Macintosh offered from 1999 to 2004. At the time, the machines were plenty fast — being advertised as the first “personal supercomputer” when they hit the market. But Father Time is particularly harsh on silicon, so they’re properly archaic by modern standards.

As such, the rear panel of one of these machines is hardly where you’d expect to run into a functional USB-C port. But thanks to the efforts of [Dandu], old has officially met new. Critics will note that it’s not real USB-C, and instead uses USB 2.0 with the more modern connector. That’s true, but considering how many commercial devices we run into that are still using the same trick, we’ll give it a pass.

So in theory, all it should take to make this possible is a USB 2.0 PCI card and some clever wiring going into the back of a bulkhead USB-C connector. Which if you zoom out far enough, is exactly what [Dandu] did. But when your dealing with a 20+ year old computer, everything is easier said than done.

For one thing, it look awhile to find a PCI USB card that would actually work under the two operating systems the computer runs (OS X Tiger and Mac OS 9). For those taking notes, a card using the Ali M5273 chip ended up being the solution, although it can only hit USB 1.1 speeds under OS 9. He also needed to find card that had an internal header connector to wire the USB-C port to, which wasn’t always a given.

[Dandu] provides some screen shots and benchmarks to show how the new port works in both versions of Mac OS, but the  most important feature is that he can casually plug his phone into the back of the machine.

9 thoughts on “Adding USB-C (Kinda) To A PowerMac G4

  1. “Archaic”.. Yeah, that sounds so great.
    But meanwhile Snow Leopard has just been ported to G4/G5 PPC by the community last year, by the way.
    It runs on real 10.6 kernal, with files borrowed from other versions.
    It’s even being possible to re-compile existing 10.6 projects freshly for PPC and stuff the resulting PPC binary together with the intel binary (universal binary).

    https://lowendmac.com/2024/mac-os-x-snow-leopard-10-6-10-6-8-for-powerpc/

  2. I’m quite surprised Dandu had difficulty finding a working USB card. Basically any OHCI-compatible chip should work, I usually chose ones from NEC. You do have to faff around with extensions on 9.2, because there’s a regression where add-in USB ports do not work. 9.1 doesn’t have this problem.

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