Usually it will be obvious when you look up the codes.

You have 2 options for the codes.

I'd bet that one doesn't exist.

What codes have you found?

I'm not sure what list of codes to use, this MB uses AMI bios and the date codes on many chips are from 1989. The bios chips and keyboard controller chip have labels with copyright 1985, 1986. I dumped the two bios chips with an eprom programmer and merged them with a utility called ROMWAK. In the ascii at the beginning of the merged BIOS dump it says "02/15/89SETUP PROGRAM FOR NEAT CHIPSET (C) American Megatrends Inc.". The AMI post codes I found for this age does not have a 24 or 25 code, it only has the 30 code and that is described as "Virtual mode memory test about to begin"

Any thoughts on what else to look for? I'm not familiar with what tasks are likely happening at the time virtual mode memory is about to be tested.

Thank you
J.W.S.

Link to codes?

This is the link to the AMI bios codes I found:
https://uxd.zendesk.com/hc/en-us/articles/360 … OST-Error-Codes

Thank you
J.W.S.

And how do the numbers translate from beeps?

Being unsure if I'm hearing 1 long or 2 short at the beginning has me confused however according to a handful of sources that give beep codes it seems there in no listings for 8 long beeps. Regardless of the first beep or beeps the 8 beeps is listed as a video card problem and I'd looked this up in the beginning. I tried 2 different video cards and even tested them in my 386. Further research today has taught me some ISA video cards require 386 instructions to work so maybe my 2 working video cards are just too new. I am working on finding an older ISA video card now.

Myne,
Your string of questions is helping me more that I initially thought they would.

Thank you
J.W.S.

Ok I did find an older video card and it was NOT the problem. This older card is an OAK Technologies ISA with OTI067 chip date code 9051. I am now thinking that something is keeping the DFI TOP-286 motherboard from communicating with the video card or some kind of ready signal or an IRQ for it, I'm just guessing again. I also found another 286 motherboard, I forget I had, and tested the OKI video card with it. The OKI video card worked fine in my Biostar MB-1212C motherboard that is dated 9103, so its slightly newer but still a 286.

Summary my DFI TOP-286 had VARTA disease. Repairs have been made but it won't complete POST and ends displaying 30 24 or 30 25 on the post analyzer card. It gives 2 high pitched short beeps then a small pause and 8 more lower pitched beeps. It does not give video to the VGA monitor even trying different video cards.

I'm looking for any ideas, or tests, or things to try.

Thank you
J.W.S.

19 Attempting to pass control to video ROM at C0000h
1A Returned from video ROM

https://blog.theretroweb.com/2024/01/20/amibi … ost-codes-list/

Everything seems to point to video.
That doesn't mean that the card is defective. It can mean it isn't getting power, or signal.

Assuming you have a multimeter, pull up the ISA pinouts, and check all the power pins.
If they all have the right voltage +/- 20%, then it's time to check for continuity.

Find the datasheet for the chipset, and check continuity between the pins and the slot. You can do this part unplugged.

Do you get different codes if you remove the video card entirely?
Would be interesting to confirm that the VGA BIOS is indeed being called but can't find the card (could indicate some problem doing I/O to the card), or if something causes the checksum to fail on the VGA BIOS, which means the built-in MDA/CGA routines in the BIOS are trying to find such a card.
I have dealt with a similar I/O issue on an XT clone board using discrete 74 series logic, but never on an integrated chipset

I just checked with no video card plugged in I get the same exact beeps, and it stops on the same POST codes 30 24 and sometimes 30 25. I also tried plugging the video card into an 8-bit ISA socket letting the back half hang in open. I read that some of these video cards from this era can work as a 16-bit or 8-bit card, anyway no change.

Thank you
J.W.S.

I checked voltages carefully with the card plugged in by probing the part of the edge tracks that are visible just above the ISA socket and voltage rails are getting to the video card. I will get the CHIPS chipset pinouts and start checking continuity of the address and data lines next.

Thank you
J.W.S.

I have some great news! I found one more bad trace from pin 25 of the 82C212 (Memory Interleaved/Page Controller). This pin 25 is named LMEGCS\ is described as LOW MEG CHIP SELECT is an unlatched active low output asserted when the low Meg memory address space (0 to 1024 Kbytes) is accessed, or during refresh cycles. It is used to disable SMEMR\ and SMEMW\ signals on the AT bus if accesses are made beyond the 1Mbyte address space to maintain PC and PC/XT compatibility. The \ after the signal names is to denote a bar across the signal name to say its active low, or signal NOT. The bad circuit was from the CHIPS 82C212B pin 25 to a M74F244P on pin 19. I don't really understand exactly what this is all about, but I can tell you the Motherboard is almost a BRICK if the pin 19 of the M74F244P is floating. M74F244P is an Octal Buffer/Line Driver with 3-State Outputs, and pin 19 is OE2\ is the active low input for enabling the second four buffers.

I was one bad trace away from having a working 16Mhz 286 but was really struggling. I started checking chipset connections and stubbled across another questionable looking trace. Thank you Myne for adding ques to keep me moving and you and Jakethompson1 probably understand better what this broken trace was doing than I.

let's just hope there are no other weak traces from the battery damage that will cause trouble later.

Thank you
J.W.S.

It always surprises me when people who clearly know the theory waaaaay better than I do (I only vaguely understand most of that) need help with the practical.

Good work 😀