I have found a new shop here in Chicago to do the 600MHz CPU chip rework, I have sent them one set of 4 boards and have been happy with their service. I am going to send them another set of boards (including one I am going to do some cache mods to) this Tuesday, if they do a good job on this set as well, I will post their contact information. I don't want to be hard to get along with by not posting the shop's information, but I want to be sure I'm giving people information for a reliable rework shop.
For the O2, when you start the computer the CPU board reads the data from the boot-mode PROM chip (the Xilinx chip) into specific registers on the CPU chip and does a Power On Self Test (POST). If the POST passes, the ip32PROM then reads that data from the specific CPU chip registers and checks that the CPU module is returning data values the ip32PROM recognizes and passes those data values on to IRIX for the system. The problem is that the data is in different registers and has different values for the RM7900 series of chips than the RM7000 series of chips. The RM7000 chips and the RM5270 chips use the same data registers so the ip32PROM sees the RM7000 chips just fine, not so with the RM7900 chips. When ip32PROM does not see a data value it recognizes (for whatever reason), it halts the system at that point.
So at least three things need to be done to get this project back on track:
1.) a way needs to be found to tell the ip32PROM the correct registers to look in for the data on the RM7900 CPU chip
2.) new values need to be added to the ip32PROM's list of possibe data values for a couple of items
3.) the setup for the L2 cache in the ip32PROM needs to be changed as the RM7900 chips start the cache memory at a different memory location than the RM7000 chips
If there is someone out there who understands the ip32PROM and how to modify the bin file, I will help them any way I can but the software part of this is beyond my understanding.
The situation with the cache upgrade is this: a rework shop is going to charge about $30 per cache chip (9 or 5 chips) to remove the old chips and another $30 per chip (5 chips) to put the new ones on. The new cache chips are about $25 each (5 chips) so the total to mod one 250MHz 1M cache Octane CPU module to 4M cache will be about $545 plus S&H, double that for a dual processor CPU module. The cost for a 360MHz Octane or 400MHz O2 module modded to 4M cache will be about $425 plus S&H. It goes without saying that this can get to be an expensive hobby very fast. I have been working on a way to do this cache rework in a more reasonable money way, at this point I just can't justify the "out of pocket" expense of several hundred dollars for something I don't
will work. I'm working on a couple ideas on this though, as I would very much like to see the performance difference of a 1 or 2M cache module vs a 4M cache module.
Anyone who has ideas or would like to help, please jump in, there is plenty of room in the O2 pool.