Giga Designs 7447a Version 2.1.0 (must be run in OS X, optionally enables OS 9 booting via separate PRAM patch from there):
https://drive.google.com/open?id=0BwMW-pNhRwrdMS1ieU5aVGVlRU0 This archive includes Giga-Meter 1.0.1, and also a reference document for voltage jumper settings. When booting OS 9 you must remove the Apple CPU Plugins file from the Multiprocessing folder in System->Extensions and run in single-processor mode.
For completeness' sake, Sonnet OS X versions are still available on their website here:
http://www.sonnettech.com/support/kb/kb.php?cat=315&expand=_a3_b400_b153&action=a3#a3 Version 3.1 is for OS X 10.3-10.4, while Version 3.2 is required for 10.5. Both the 'standard' CPU model and the MDX model are supported by these shared installers. OS 9 booting is integrally enabled as part of these firmware updaters. The OS 9 version of the Sonnet installer is no longer hosted there, but likanen provided a link to it in the previous post:
I posted this link on another thread (where I'm trying to decompile the driver to understand what it does) but here is the link to Sonnet G3/G4 Extension v 3.1:
http://download.system7today.com/ce_install_v31.sit
You need that to get the OS 9 extension if you were to run the firmware update from OS X first. When booting OS 9 you either need to remove the Apple CPU Plugins file from the Multiprocessing folder in System->Extensions and run in single-processor mode, or to enable dual processing you need to use the alternate hacked version of the file:
https://drive.google.com/open?id=0BwMW-pNhRwrdbFI3bXAzWU8zRzg The hacked file is flagged as Apple Version 3.5 from "Mac OS CPU Software 4.5". I don't know which version of the Mac OS or installer/updater came with the original 'untouched' 3.5 version of the file. If someone can track down the original for comparison, that would be very helpful. If the alterations to this file can be incorporated into a later revision of that file then it may be able handle more versions of the dual CPU upgrades and also more gracefully. The latest standard version of the file I have is 4.0.1 which came from the Unsupported G4s 9.2.2 ASR image.
On a related note, I'd really love to get hold of a Giga Designs 1.33GHz 7455 upgrade for MDD just for completeness' sake of my collection. The following firmware updater Version 3.0.1 says it extends compatibility beyond 7447a to include 7455 and 7448 CPUs and still allows the OS 9 PRAM patch:
https://drive.google.com/open?id=0BwMW-pNhRwrdTkFUUjRlS1MwNms I never used this later version because the earlier one I linked above was sufficient for my 7447a upgrade to work. It should prove interesting to dig around inside this one though.