Got write-back -mode working with Cyrix DX4-jumpers.

Edit: ...but it wasn't stable.

New problem, I can't get any Sound Blaster work on this. FM music works with SB PRO2 and Aztech Sound Galaxy (SB PRO compatible) but no samples. Tried with IRQ5 and IRQ7 both cards. Duke Nukem 3D setup there's Test FX and it says invalid IRQ or IRQ conflict. In games Gods gives only FM music and Doom same thing.

Tried with different CPU too.

Edit: seems like DMA 1 on motherboard is broken. DMA 3 and 5 works.
Edit2: it was the VLB-IO! It took DMA 1 even if printer port was in SPP-mode or disabled. Jumpered it to DMA3 and now DMA1 works.
Edit3: crackling and popping still on digitized samples. Something is wrong with the motherboard
Edit4: Wont happen with any other display card... Cirrus 5434 makes it.

Little update:
got another 128KB cache from Electromyne and put those in place, works with no problems.

Updated bios to newest AMI Winbios, jumpered CPU to 5x86-settings and got Writeback-cache working (with old bios it didnt even posti with 5x86 jumper settings).

Only downside is that I cant get 40MHz FSB stable, tried everything in bios but no. Maybe it's the CPU that wont get that high... @33MHz works with every setting maxed out.

Edit: it was the CPU! 3x50MHz works with no problems! Even display card! BTW, it gives 34MB/s with VGASPD.EXE
Edit2: I cant get this mobo stable with WB-cache, tried every bios settings and different clocks but no. Jumpered it to P24T settings and now cache is WT and everything works, bit slower though.

Specs are:
PC Chips M912 v1.4 256KB cache
Am5x86-133
1x 32MB SIMM
2GB Quantum Bigfoot
LG DVD-RW 😀
Cirrus 5434 2MB
Gravis Ultrasound Classic 1MB
Sound Blaster PRO 2
SMC Ethercard 16 Elite

What is the difference between 12/02/1995X and 12/01/1995 BIOS files?
Is AMI better than Award?

RiP wrote on 2021-07-20, 21:37:

What is the difference between 12/02/1995X and 12/01/1995 BIOS files?
Is AMI better than Award?

I recommend the AMI BIOS. In particular, it seems to handle IDE drives up to 8.4GB fine.
The Award files floating on the first page of this thread, if you see there is a note that they may not actually be for this board.
I have two M912s, both sick at the moment... but one did come with the 1994 Award BIOS. It has hard drive size bugs and also has the bug where it resets the year to 2094 (it's possible to fix that)

Thanks, and what is the difference between these two AMI BIOS files: 12/02/1995X and 12/01/1995 ?

Well, I found no difference:

In my tests 1995X is a little faster than 1995D.
But 1995D has more bandwidth. Probably to compensate no L2"," ram timings are pushed to death. What I can't get is just how.
I'll post pics in a few days.
I didn't go farther than speedsys, I should have done some benchmarks.

I have multiple M912 boards and got frustrated with them as certain BIOS versions will work on certain boards but not on others.

All of mine have real cache.

There is also supposed to be a way to have both the AMI and Award BIOS on the same board and then be able to change between then with a jumper. Never could get that working.
The AMI BIOS is better for some things and the Award BIOS is better for other things. I really wanted to test both without having to swap the BIOS chips back and forth.

cyclone3d wrote on 2021-08-16, 18:06:

I have multiple M912 boards and got frustrated with them as certain BIOS versions will work on certain boards but not on others. […]
Show full quote

I have multiple M912 boards and got frustrated with them as certain BIOS versions will work on certain boards but not on others.

All of mine have real cache.

There is also supposed to be a way to have both the AMI and Award BIOS on the same board and then be able to change between then with a jumper. Never could get that working.
The AMI BIOS is better for some things and the Award BIOS is better for other things. I really wanted to test both without having to swap the BIOS chips back and forth.

I was thinking to desolder the BIOS socket and put a zif socket to make things faster.
My main concern is that all the bios versions that are around aren't really optimized and should be tweaked to allow all the board has to offer.
My assumption is based on how cheap they went on cache, thus making me think that compatibility aside they didn't bother doing real hard improvements.

I'd like to stress how it was impossible for me to upgrade the existing BIOS on the rom that came with the board and even with new roms.
They did strange stuff 😀

I designed bios switcher with slide switch. Personally use them in asus p65up5 (3 different daugtherboards) and with MSI6168 (Award/AMI). Currently only 32pin version.
If someone will need then can contact with me.

mt777 wrote on 2021-08-16, 21:40:

I designed bios switcher with slide switch. Personally use them in asus p65up5 (3 different daugtherboards) and with MSI6168 (Award/AMI). Currently only 32pin version.
If someone will need then can contact with me.

A pic, please!

dj_pirtu wrote on 2021-06-15, 14:40:

Little update: got another 128KB cache from Electromyne and put those in place, works with no problems. […]
Show full quote

Little update:
got another 128KB cache from Electromyne and put those in place, works with no problems.

Updated bios to newest AMI Winbios, jumpered CPU to 5x86-settings and got Writeback-cache working (with old bios it didnt even posti with 5x86 jumper settings).

Only downside is that I cant get 40MHz FSB stable, tried everything in bios but no. Maybe it's the CPU that wont get that high... @33MHz works with every setting maxed out.

Edit: it was the CPU! 3x50MHz works with no problems! Even display card! BTW, it gives 34MB/s with VGASPD.EXE
Edit2: I cant get this mobo stable with WB-cache, tried every bios settings and different clocks but no. Jumpered it to P24T settings and now cache is WT and everything works, bit slower though.

Specs are:
PC Chips M912 v1.4 256KB cache
Am5x86-133
1x 32MB SIMM
2GB Quantum Bigfoot
LG DVD-RW 😀
Cirrus 5434 2MB
Gravis Ultrasound Classic 1MB
Sound Blaster PRO 2
SMC Ethercard 16 Elite

The fact that Am5x86 is meant to work with 3.45V instead of 3.3 could be what makes it unstable with WB L2?
Maybe your cpu isn't a 3.3V version.

The motherboards L2 cache didnt work in WB mode at all, no matter what clock or CPU. Only in WT mode.

Now I have Asus PVI-486SP3 and run 5x86 @160MHz. 😀

dj_pirtu wrote on 2021-12-10, 05:44:

The motherboards L2 cache didnt work in WB mode at all, no matter what clock or CPU. Only in WT mode.

Now I have Asus PVI-486SP3 and run 5x86 @160MHz. 😀

I realised I have to quit pushing this board as it is what it is.
It works well but there is better, like your Asus.
There a lot out in the wild, maybe a bios update would have been a good thing but go ask PCChips 🤣 Probably some work better than others.

Sorry to bump this thread but been playing with 2 M919 v1.7 motherboards with REAL cache for a while, and both came from the factory with AWARD bioses, one is dated 10/05/94 and the other 11/03/94.

I used my GQ4X EEPROM burner to get the bios images directly from the chips. I'm uploading them both here in case anyone wants to try them, or compare them, or whatever. Is there any other AWARD bios with a newer date? All of the ones I see with 95 date code are AMIBIOS ones.

Am386DX-40 wrote on 2022-01-07, 18:06:

Sorry to bump this thread but been playing with 2 M919 v1.7 motherboards with REAL cache for a while, and both came from the factory with AWARD bioses, one is dated 10/05/94 and the other 11/03/94.

I used my GQ4X EEPROM burner to get the bios images directly from the chips. I'm uploading them both here in case anyone wants to try them, or compare them, or whatever. Is there any other AWARD bios with a newer date? All of the ones I see with 95 date code are AMIBIOS ones.

Nice, I'll try them both when I'll go back to this board.
Did you test them with Amd Am5 P75? or Cyrix 5x86?

Nexxen wrote on 2022-01-07, 21:01:

Nice, I'll try them both when I'll go back to this board.
Did you test them with Amd Am5 P75? or Cyrix 5x86?

No, I took them out and put the latest 12/01/95 AMIBIOS in there and tested with that, will test the original AWARD bioses in a couple of days.

Am386DX-40 wrote on 2022-01-07, 21:30:

Nexxen wrote on 2022-01-07, 21:01:

Nice, I'll try them both when I'll go back to this board.
Did you test them with Amd Am5 P75? or Cyrix 5x86?

No, I took them out and put the latest 12/01/95 AMIBIOS in there and tested with that, will test the original AWARD bioses in a couple of days.

I used that bios too but forgot to put lowest latencies (2221) and did all the benchmarks with high.
I have to start over with Am5... 🙁
Probably just a -5% but still something.

On request of another M912 user, I made a detailed analysis of the 10/05/94 and 11/03/94 Award BIOSes for this board back in 2019, to see if patching for Am5x86-P75 was possible.
So I’m joining here to share my findings.

The differences I found were:
- The 10/05/94 BIOS supports 2 IDE drives (only the Primary IDE channel), while the 11/03/94 BIOS supports 4 drives (Primary and Secondary IDE channel)
- The 11/03/94 BIOS adds support for the Am486DX4 (non-WB) CPU, so the 10/05/94 doesn’t and will indicate an Am486DX4 as an 80486DX2.
So only 2 small differences, which is to be expected in view of the 1 month difference in compilation date.

When looking at missing support and bugs in both these BIOSes, there are quite some similarities:
- Year 2094 bug
- 2GB HDD display limit bug
- No support for Enhanced Am486DX2/DX4, Am5x86, and Cyrix 5x86 CPUs.
- No x4 multiplier or L1 cache WB support for these later CPU models. L1 cache WB is only supported for Intel P24D, P24T, and Cyrix 486 models.

As the 11/03/94--2C4X6H01-00 BIOS is the latest Award BIOS from PCChips, many M912 users turn to the AMI 12/02/1995X BIOS when running an Am5x86-P75.

Recently I have been looking at the Award BIOS for the Amptron DX-6900, an M912 clone. However this 09/08/95-UMC-498GP-2C4X6B13-00 BIOS is indicated for the v1.4 board only. See https://www.ultimateretro.net/nl/motherboards/6821
This 09/08/95 BIOS is free from the above bugs and supports all later 486 models, except the Am5x86 in x4 multiplier mode. However, this can be patched. 😉

Did any of you try this BIOS on a DX-6900/M912 v1.7?

Cheers, Jan