Check your battery, some of my newer coin batteries have had to be cleaned on the bottom right out of the package (some type of film)..

Horun wrote on Yesterday, 17:43:

Check your battery, some of my newer coin batteries have had to be cleaned on the bottom right out of the package (some type of film)..

Thanks for the suggestion. I tried using the external battery connection too so I could rule out the battery holder.

Success! (well almost)...

I found some corrosion on a trace coming from the SIS 85C407 chip. Grinding down the trace revealed the corrosion had completely eaten all the copper, so the link was broken. After repairing the trace, I found the same trace had corrosion towards the end where it went into a VIA. That was a nightmare to fix as the most of the copper was gone around the VIA. I actually had to drill down a little into the VIA to try access some copper.

Issue 1, 2 and 3 are now resolved.

Issue 4 - When external cache is enabled. I motherboard won't boot into DOS. I've double checked my jumper settings for CPU and cache but they are correct. I also installed new cache chips to go from 128K to 512K but the issue still persists. Another strange thing is that it's showing only 256KB of cache.

Good work !

Issue 4 is now resolved. There was some corrosion on the cache slots. Using some WD40 contact cleaner and installing/removing them a few times resolved the issue.

Issue 5 - cannot boot into DOS when the BUS is set to 40MHz (160MHz CPU). I disabled the external cache but that didn't work. I then disabled the CPU internal cache and that worked. Increasing the CPU voltage and booting via XTIDE does not help either. Anyone have any ideas?

The motherboard is now working perfectly (except for issue 5).

Issue 5 is now resolved. I swapped the AMD AMD-X5-133ADW with another one I had and she booted perfectly. So I've come across my first AMD AMD-X5-133ADW that can't be overclocked.

I have 3 questions;

Question 1 - I did notice the performance of this board is not as good as a PCChips M919 or a Shuttle HOT-433, both have the dirty tag L2 cache enabled. The dirty tag is not enabled on this board. Is it supposed to be enabled? I only get 11.3 fps in Quake (@160MHz). On my DX4-100 I get 11.9. Although I am using a crappy Trident 8900D and 128KB L2 20ns cache. Anyone have any ideas? I’ve ordered 10x IS61C1024-15N but I’m guessing they won’t make much difference. -Edit- Looks like I may have to modify the BIOS to get the dirty tag? Re: 486 cache/ram speed issue with write-back.

@feipoa saves the day again, here is his patched BIOS enabling the dirty bit Re: Evolution of a Socket3 System to a POD @100MHz

@PC-Engineer has a great couple of posts on how to max the performance of this board Re: Evolution of a Socket3 System to a POD @100MHz

Question 2 - Can the tag cache be larger than the recommended size in the manual? I was hoping to use 1x 128kb chip for tag and 8x 128kb chips for the cache (1MB).

Manual actually says 64kb or 128kb chips can be used for 1MB.

Question 3 - I have BIOS “11/03/95-SIS-85C471-I486SV2G-00” (0402.1) installed. There is a newer beta BIOS “ 11/19/97-SIS-85C471-I486SV2GC-00” (0402.001). What is the difference?

Another retro board fully restored! Woot