feipoa wrote on 2021-12-11, 21:45:
Looks like you are already hitting the FPU issue.
No FPU issue because the FPU is not yet installed on the module.
I see.
feipoa wrote on 2021-12-11, 21:45:
Next up - "cyrix.exe -i1 -r" - instant hang ...
After some time i realized that if the FPU on the upgrade module is enabled via the available switches the above command locks the system.
I have the FPU switch set to disabled on my module and my FPU is not installed.
In my case the initial problem was faulty FPU that came with the module. For some reason it was hanging the system upon running cyrix.exe.
feipoa wrote on 2021-12-11, 21:45:
At the end i pulled my daughter's microscope, quickly discovered and fixed the problems.
That microscope will be seeing more electronics action in the future for sure.
What was the problem?
Few pins were shortened from the soldering in spots that were impossible to see with naked eye.
feipoa wrote on 2021-12-11, 21:45:
Running the cyrix.exe command in combination with enabled FPU didn't lock anymore, but the FPU was still unavailable.
What action taked allowed it not to hang any more?
Replacing the FPU.
While that stopped the crashes i was still unable to make the system to see and use it. Will be interesting if you can get it running.
feipoa wrote on 2021-12-11, 21:45:
- write access to CompactFlash cards is flaky with the SXL2 CPU, works fine with mechanical HDDs.
Interesting. I'm OK to use mechanical HDDs if I run into this issue.
Yea, this issue is not unique to this specific case.
I noticed on several other occasions that using SXL2 CPUs in 286/386 motherboards can cause such problems with CF cards.
feipoa wrote on 2021-12-11, 21:45:
- adding more extension cards such as SoundBlaster, LAN, etc. makes the system unstable.
Holy crap.
Yeppp.
Keep in mind that i was pushing the system hard - up to 70MHz on the CPU.
Cannot remember what the outcome was with lower base frequencies.
I was not interested in that. Even 15MHz base hurt overall perf significantly - especially the disk metrics.
So going lower than that was of no interest to me.
feipoa wrote on 2021-12-11, 21:45:
About the FPU - will try it on few more "classic" 286 motherboards with the hope that the upgrade module was tested on them during its development, to see if something will make it "click".
Any update?
Never proceeded with that. 😁
feipoa wrote on 2021-12-11, 21:45:
My 486 SuperChip module is a lot smaller than your upgrade adapter. Usually smaller is better. I have 8 dip switch settings, but no manual. That's 256 different variations - probably too many for me to try each one. I might be able to make 3 static and do 32 iterations.
Extra switches most likely mirror some of the cyrix.exe command flags.
feipoa wrote on 2021-12-11, 21:45:
Did your upgarde module have no issue with the DLC, that is, only had issue with the SXL? Another difference between our modules is yours is using 32-bit DLC/SXL, while mine is using 16-bit SLC/SXLC chips.
Does your module also contain a PLL clock doubler on the PCB?
Cannot remember what was the story with DLC chips. Can check if we decide to drill there. I am inclined to say no. Because DLC chips don't have issues with writes to CF cards on 386 motherboards.
Yes. There is a clock doubler.
The best i could do is with 70MHz crystal (17.5MHz base frequency) which gets doubled once through the interoposer and doubled twice with software flag = 70MHz CPU speed.