Hi Nexxen,

Thanks for your detailed benchmarking of the M912 J.2 BIOS against the AMI versions!
I have a comparable UMC498F board with VLB IDE now (Aquarius/BCOM MD-4DUVC Ver 2.11) to help with further testing and compare scores with. 😊

However at the moment I’m busy finishing the 25th anniversary update of my CHKCPU CPU Identification utility and I expect to continue with the M912 Award BIOS project in a week or two.

Jan

@Chkcpu, any news? I've just got this board with 5x86 P75 and now see that it will require your patch 😀

There was another board from that seller of v1.7 with not so fancy black ISA slots that detected that CPU as DX4-486-100S (or something like that) but I preferred this one that doesn't even boot with 5x86 (though I see post activity). I'll try some other BIOS versions for sure but seems like your solution is going to be the best one.

Edit. Interesting - I have exactly the same mobo as BastlerMike did (the first comment author). It has BIOS ver 12/02/1994 from retroweb. I updated it to the BastlerMike's BIOS (ver 12/01/1995 from retroweb) and it works. And detects my CPU as 5x86 with 133MHz frequency. Jumpers were set to the Cyrix settings from the first try. Will check the cache settings later.

Figured I would chime in on this as well.

I have v1.7 of this board with a 120 mhz AMD (Am486DX4-100SV8B). The BIOS has an option for write back and write thru (though I later noticed it says 'L1'). This is definitely supported by the CPU.

The L2 cache has been upgraded to 256 K with appropriate sized tag, and that all works in write through mode.

However the system won't seemingly work with write back enabled. I've tried 3 different jumper settings for CPU type (as per documentations) and turning on WriteBack in BIOS, but they all result in either the system straight up freezing at boot, or cachechk will report extremely high results for the megabyte #1 and claim there's no cache installed.

I've tried tweaking every BIOS setting and also 'auto' mode to no avail.

So at this point I can only think I need an updated BIOS, unfortunately I don't have an eeprom tool.

I'm open to other suggestions though 😀

Ehm.... To get an eeprom tool? 😀 It's useful even for arduino flashing not to mention any bios related stuff. And a bunch of W27C512 chips, they are pretty often used on cards of this era and can be erased without UV-lamp.

rkurbatov wrote on 2023-03-30, 21:43:

Ehm.... To get an eeprom tool? 😀 It's useful even for arduino flashing not to mention any bios related stuff. And a bunch of W27C512 chips, they are pretty often used on cards of this era and can be erased without UV-lamp.

Well yeah that's a possible solution, I don't know if an updated BIOS would even fix the issue, hence my request for other ideas 😁

rkurbatov wrote on 2023-03-28, 19:56:

@Chkcpu, any news? I've just got this board with 5x86 P75 and now see that it will require your patch 😀

There was another board from that seller of v1.7 with not so fancy black ISA slots that detected that CPU as DX4-486-100S (or something like that) but I preferred this one that doesn't even boot with 5x86 (though I see post activity). I'll try some other BIOS versions for sure but seems like your solution is going to be the best one.

Edit. Interesting - I have exactly the same mobo as BastlerMike did (the first comment author). It has BIOS ver 12/02/1994 from retroweb. I updated it to the BastlerMike's BIOS (ver 12/01/1995 from retroweb) and it works. And detects my CPU as 5x86 with 133MHz frequency. Jumpers were set to the Cyrix settings from the first try. Will check the cache settings later.

Hi rkurbatov,

Due to lack of time and new ideas, my M912 Award BIOS project has been dormant these past months. But a week ago I pulled my UMC498F board (Aquarius/BCOM MD-4DUVC Ver 2.11) out of storage, installed an Am586-P75 and figured out how to set the jumpers for x4 multiplier and L1 cache WB mode.

This worked fine with my M912 patch J.2 BIOS, however the incorrect CPU speed indication by the BIOS (100MHz instead of 133MHz) was present here as well. So this is definitely a BIOS bug and not a problem of the M912 board. 😉
I’m still investigating this bug and I hope to have a fix soon.

Okay, you got it working with the AMI 1995 BIOS! But you may have to change some jumpers to get it working correctly in L1 cache WB mode.

@drosse1meyer, reading about your L1 cache WB problem with the Am486DX4-120 SV8B, I’m convinced a BIOS update will fix this. When you get hold of an EEPROM programmer, the AMI 1995 or 1995X, or my Award M912_J2 BIOS will fix the issue.

Cheers, Jan

Chkcpu wrote on 2023-04-02, 14:41:

rkurbatov wrote on 2023-03-28, 19:56:

@Chkcpu, any news? I've just got this board with 5x86 P75 and now see that it will require your patch 😀

There was another board from that seller of v1.7 with not so fancy black ISA slots that detected that CPU as DX4-486-100S (or something like that) but I preferred this one that doesn't even boot with 5x86 (though I see post activity). I'll try some other BIOS versions for sure but seems like your solution is going to be the best one.

Edit. Interesting - I have exactly the same mobo as BastlerMike did (the first comment author). It has BIOS ver 12/02/1994 from retroweb. I updated it to the BastlerMike's BIOS (ver 12/01/1995 from retroweb) and it works. And detects my CPU as 5x86 with 133MHz frequency. Jumpers were set to the Cyrix settings from the first try. Will check the cache settings later.

@drosse1meyer, reading about your L1 cache WB problem with the Am486DX4-120 SV8B, I’m convinced a BIOS update will fix this. When you get hold of an EEPROM programmer, the AMI 1995 or 1995X, or my Award M912_J2 BIOS will fix the issue.

Cheers, Jan

thank you

@Chkcpu thank you!

One more question - are there some better explanation of what do the processor jumpers really do? That's so messy, there are two of multiplier sets (one for AMD, one for Intel), one unknown jumper and just a set of somewhat random settings like 1-2, 3-4 or 2-3 in the main jumper block. The only clear part is voltage (though why 3 jumper blocks for it?)

rkurbatov wrote on 2023-04-02, 22:28:

One more question - are there some better explanation of what do the processor jumpers really do? That's so messy, there are two of multiplier sets (one for AMD, one for Intel), one unknown jumper and just a set of somewhat random settings like 1-2, 3-4 or 2-3 in the main jumper block. The only clear part is voltage (though why 3 jumper blocks for it?)

Ahh, jumper hell. 😊
The reason behind all those jumpers on 486 boards is best explained by taking a look at this website:
http://ps-2.kev009.com/eprmhtml/eprmx/h12203.htm

Socket 3 boards can take a lot of different 486 CPUs. The above resource shows the wild variety of pin-outs on these CPUs that needs to connect to the correct chipset pins. That’s the job of all those jumpers.
In addition, many 486 chipsets need trapping jumpers to match its functionality with the installed CPU model.

The 3 Vcore voltage jumpers actually carry the current for the CPU and are just connected in parallel to divide the load. Using only one jumper there would be unreliable.

Jan

Thank you, Jan!