Date: Fri, 21 Jan 2005 21:43:19 -0500 From: Colin <[EMAIL PROTECTED]>
Jeff Walther wrote:
All that said, there'd never be any reason to install a ROM in the 8600/300 unless you were a super firmware hacker. The 8600/300 already has the latest ROMs ($77D.34F5). There is no later improved ROM code for that machine--unless you write it yourself.
However, there is a small benefit in installing the 8600/300 ROM code ($77D.34F5) into earlier x500 and x600 machines. The $77D.34F5 code solves an incompatibility with G3 processors and speculative processing. If you put the $77D.34F5 ROM in one of those earlier machines you can enable speculative processing on your earlier machine for an imperceptible boost in performance.
I assume all of this applies to an 8500, since they are the same family? Is the 8600/300 ROM SIMM hard to come by, because I'd like to put one into my 8500 if/when I decide to get a G3 upgrade. Or maybe Apple (or someone) made the ROM flash-upgradeable (like a PC's BIOS)?
The ROM is not flash upgradeable on that generation of machines. It's on a mask ROM which means the code is inherent in the hardware. The mask ROMs can be replaced with Flash chips, which doesn't make it reprogramable, it's just easy to program the flash chips out of the machine and then they're read just like a ROM would be once they're in the machine.
As far as I know there are no 8600/300 ROM DIMMs available because none were made by Apple. All the $77D.34F5 ROMs shipped by Apple were soldered to 8600 Enhanced or 9600 Enhanced machines (the 250, 300, 350 MHz machines).
I made a few $77D.34F5 DIMMS to experiment with and eventually sold them to folks who had the rare 9500 motherboard with no ROM soldered down. There were a few 9500 boards made which were shipped with a ROM module instead of having soldered down ROMs. So the folks who somehow had these boards with no ROMs had useless boards.
But as I wrote, the performance improvement from enabling Speculative Processing is tiny. There's no reason not to just operate your G3 with Speculative Processing disabled. In fact, I think that some of the later software utilities that come with G3 upgrades just do that automatically and don't give you a choice.
Jeff Walther
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