Significantly better performance on a Sparcstation 10 with an older ROM?

[tokenalt]

Hello all.

A few months back I got an ss10 on ebay because it had some interesting framebuffers in it (tech source GXTRA/1) and it turned out to have 2 working HDD with lots of software on it but that's another story. The machine other wises seemed like a rather generic early ss10 so I didn't think much of it at first. However I noticed it had a v2.9 ROM and since I'd never used an ss10 with an early ROM I decided to run some quick benchmarks on it just for fun and to my surprise the machine was around 20% faster than another machine with the same CPU but a v2.22 ROM. I swapped some hardware around and ran some more benchmarks and the machine was consistently around 20% faster than my other machines. So finally I pulled the EPROM out of the machine and stuck it in another machine and now it's performing faster as well.

So now I'm posting here to ask if anybody knows what's going on with this ROM. I'm attaching the ROM so people can test it on their own. This ROM should work with all Supersparc I in uniprocessor mode, for SMP it only supports cached CPU. No Hypersparc or Supersparc II support.

 

[mdog69]

ISTR that the boot ROM does the normal basic hardware start up, and then launches the forth interpreter, which runs commands to set things up (including scanning other s-bus cards for setup code) and then finally ends up running the boot command, if boot is enabled, or dropping to the ok prompt if it isn't.
A comparison of the forth commands in the PROM might yield some information (assuming it's stored as plain text and not precompiled in some way). Unfortunately that's way beyond my abilities.
It may be possible to copy the required bits of code from the old PROM or create code to undo what the new PROM does and store it an nvramrc file for execution at boot time, so you can get the new stuff from 2.9 with the performance of the old version.