Hi Totalgearhead,

Welcome to Vogons!

This 09/15/97-i430TX-2A59IA29C-00 BIOS-ID identifies this BIOS as for an A-Trend ATC-5000 board. So Progen must have used an A-Trend BIOS for their TX430B board.
This makes sense because these boards are practically identical. Only the location of the SIMM and DIMM slots is different.

https://theretroweb.com/motherboards/s/a-trend-atc-5000#bios
I believe that an ATC-5000 BIOS should work fine on your TX430B, like the latest Ver. 1.08a.

Note that a 0D -> 41 POST code sequence means that the BIOS Bootblock detected a BIOS Checksum Error and entered the BIOS Recovery mode. You should be able to see this Error message when using an ISA Videocard.
Because these Award v4.51PG BIOSes are compressed, the Bootblock first checks the first Mbyte of RAM before it copies itself there to start the decompresses process. The Bootblock then performs a checksum check on the decompression engine and the still compressed Main System module in RAM. If these checks fail, the BIOS will enter Recovery mode.
After the BIOS decompression stage, an additional integrity check is done on the decompressed modules in RAM, before control is passed to them to continue POST. If this additional check fails, the BIOS will enter Recovery mode as well. The BIOS could have become corrupted.

But if you still get the 0D -> 41 POST code sequence with a freshly flashed 1.08a BIOS copy, and you flashed including Bootblock, then there is probably something wrong with your memory system. This can be the RAM sticks, the SIM/DIMM slots, broken motherboard traces of the memory address or datalines, or bad caps in the memory supply.

Hope this helps.
Cheers, Jan

Edit: Expanded the BIOS checksum logic write-up, to make the decisions to enter Recovery mode more clear.

Chkcpu wrote on 2025-10-26, 15:45:

Hi Totalgearhead, […]
Show full quote

Hi Totalgearhead,

Welcome to Vogons!

This 09/15/97-i430TX-2A59IA29C-00 BIOS-ID identifies this BIOS as for an A-Trend ATC-5000 board. So Progen must have used an A-Trend BIOS for their TX430B board.
This makes sense because these boards are practically identical. Only the location of the SIMM and DIMM slots is different.

https://theretroweb.com/motherboards/s/a-trend-atc-5000#bios
I believe that an ATC-5000 BIOS should work fine on your TX430B, like the latest Ver. 1.08a.

Note that a 0D -> 41 POST code sequence means that the BIOS Bootblock detected a BIOS Checksum Error and entered the BIOS Recovery mode. You should be able to see this Error message when using an ISA Videocard.
Because these Award v4.51PG BIOSes are compressed, the Bootblock first checks the first Mbyte of RAM before it decompresses its modules there. If this memory check fails, the BIOS will enter Recovery mode.
Also, if this memory check passes, an additional integrity check is done on the decompressed modules in RAM, before control is passed to them to continue POST. If this additional check fails, the BIOS will enter Recovery mode as well. The BIOS could have become corrupted.

But if you still get the 0D -> 41 POST code sequence with a freshly flashed 1.08a BIOS copy, and you flashed including Bootblock, then there is probably something wrong with your memory system. This can be the RAM sticks, the SIM/DIMM slots, broken motherboard traces of the memory address or datalines, or bad caps in the memory supply.

Hope this helps.
Cheers, Jan

Thank you Jan, I tried that Bios (again) and have been testing random bios files including that one as it has the same string and the 5030 to name a few. This particular BIOS re-test got stuck at the 41->0D still. I have tested and verified and or replaced all the caps in this board. I will get out my ISA video card to see what that shows me then I will check the voltages on the memory slots. I have looked over the board with a microscope and see no damage or missing traces? I have tried both SIMM and DIMM memory and its gives the same result. With No memory it halts before that at C1,C0 i believe. I appreciate the response and will report back. Thanks again.

I have tested the voltages to both types of memory and they are correct. I am still getting the 0D/0C → 41/0D then constant beeps. I will verify the clock crystal and then start looking at the SMC fdc37m672 chip. If anybody has any guidance to troubleshoot the memory side of the board I would appreciate any input thank you.

Totalgearhead wrote on 2025-10-27, 11:38:

I have tested the voltages to both types of memory and they are correct. I am still getting the 0D/0C → 41/0D then constant beeps. I will verify the clock crystal and then start looking at the SMC fdc37m672 chip. If anybody has any guidance to troubleshoot the memory side of the board I would appreciate any input thank you.

If you have an (E)EPROM programmer, can you make a copy of your present BIOS chip contents and sent it with your reply? So I can check if there is any corruption.

For further troubleshooting, a list of all POST codes from the first C0 to the last 41 would help. Most POST analyzer cards have a “step back” button to view all stored POST codes.
If you can get this POST sequence with the ATC-5000 v1.08a BIOS loaded, then I can compare it with the Bootblock code and see where it goes wrong.

Regards, Jan

Thank you Jan, i have retrieved the codes during boot and working backwards they are: 41,0d,0c,01,c5,0c,c6,c1,00,c0

I have uploaded the BIOS from my chip that you recommended (ATC-5000 latest Ver. 1.08a) and gave the above codes. Thank you for the help, I appreciate it. I'm not at all able to decipher a BIOS or understand whats happening behind the curtain.

Totalgearhead wrote on 2025-10-27, 23:16:

Thank you Jan, i have retrieved the codes during boot and working backwards they are: 41,0d,0c,01,c5,0c,c6,c1,00,c0

I have uploaded the BIOS from my chip that you recommended (ATC-5000 latest Ver. 1.08a) and gave the above codes. Thank you for the help, I appreciate it. I'm not at all able to decipher a BIOS or understand whats happening behind the curtain.

Thanks for the BIOS dump and the POST sequence.
The BIOS EEPROM contents is identical to the ATC-5000 1.08a BIOS, so no problems there.

The POST code sequence needs some further investigation.
I do know that on the Award v4.51PG BIOS the POST steps 01, 0C, 0D, 41 are all part of the Recovery mode. So the decision to jump to recovery is made before that.
The first POST codes are also common to these Award BIOSes.
C0 – This first step is the early chipset initialization, including RTC, system ports, and DMA page registers.
00 is not a POST step, but just a spurious code emitted during reset of the DMA Page registers.
C1 - This step is all about testing RAM. First a RAM type detection is made, followed by a test of the first 256KB of memory. If this test fails, a beep code is emitted and POST is halted, exactly as you saw when no RAM was installed.

To see what the BIOS is doing in the subsequent steps C6, 0C, and C5, I will need to make a disassembly listing of this BIOS’s Bootblock and analyze it. I expect to have some time for that tomorrow.

Did you already try an ISA videocard to see if that works? The last POST step 41 is a search for a floppy drive and bootable media, and this step should be visible on screen. Note that if a bootable floppy is found, POST will cycle to step FF, indicating a successful transfer of control to the disk’s bootsector code. Please try that as well.
These checks will help with the troubleshooting.

Regards, Jan

That is great information Jan, I started to read your post here regarding BIOS patching to start at least understanding it more. I have tried an ISA video card and it isnt giving anything to the screen to see. I have tried a floppy to the onboard controller and also an ISA controller and both do not give any floppy seek at all. I appreciate you looking into this. I am curious what you will find and await your response for the next task to troubleshoot. In the meantime I will try again on the ISA Video Card and also the floppy, as your explanation gives me some understanding of what is expected to happen around step 41. Thank you!

Update, i had another ISA drive control card, i hooked the floppy up to that and I now have the floppy seeking!, the Analyzer Card is now displaying 41->FF, I have known good boot disk in there, it sounds like its reading it but i have no video still. I tried different slots with my ISA Video Card and I tried my PCI video cards also, no video. Thank you.

I’m glad to hear the floppy boot is working now, but the no-video issue is a bad one.
This is what you should see with an ISA videocard fitted, and an MSDOS 6.22 boot floppy in the drive.
Note that the bootimage I used has no AUTOEXEC.BAT, so I had to hit Enter twice to skip the request for the correct date and time.

Before step 41, the Recovery BIOS searches for and initializes an ISA videocard in POST step 0D. If it can’t find a videocard, a beep is output to the speaker and it skips the rest of POST_0D, to continue with step 41 for a possible blind recovery.
Do you hear this beep?
Note that this beep is followed by a high/low chime when step 41 can’t find a bootable media.

I don’t know yet why the BIOS can’t find the videocard. Maybe there is a stuck address line on the ISA bus, or something else related to addressing the bus.
To learn more about the possible failure, a blind BIOS reflash by the Recovery BIOS may tell us something. We know that the BIOS in the flashchip is good, and it should stay that way if we reflash the same BIOS in the board. But if this scrambles the BIOS, there is a high chance there is an addressing problem on the board.

So try this; copy Awdflash.exe and the 5000108A.BIN BIOS on the bootable floppy, and create an AUTOEXEC.BAT with this command:

AWDFLASH 5000108A.BIN /Py /Sn /Cp /Cd /Cc

This command will execute the flash without any user interaction.
The three /C switches clear the PnP, DMI, and CMOS data.
During the flash, there should be changing codes on the POST analyzer card. These are not from the BIOS, but are progress codes generated by Awdflash.exe. The actual flash is indicated by code 1B. After this there are only 2 more steps, the verify phase (code 1C), and the flash complete phase (code 1D).
When Awdflash terminates, an FF code is shown.
When floppy activity stops and the drive light goes out, switch the power off. Remove and read the BIOS flashchip in your programmer and put it up here. I hope its contents will be educational. 😉

Here is a copy of Awdflash.exe that should work.

This is Awdflash v7.95 I use for socket 7 boards. Works here on any socket 7 board with an Award BIOS, except Asus. (For Asus socket 7 boards with AWD BIOS I use Aflash v2.02).

I’ve completed the disassembly of the Bootblock now, and will continue to analyze POST steps C6, 0C, and C5 to see if I can find any clues there.

Cheers, Jan

Thank you Jan for the followup. I woke in the middle of the night last night recalling where this missing BIOS chip may be? When i got the board the BIOS chip was installed backwards and by the time i realized that it was burnt. Not sure if the previous owner already turned it on or that was my fault for not checking first. So the original BIOS chip is an Intel 28F001BX and I bought to replace it an SST39SF010A. I looked right away and found incompatibility with the chip i bought!

I completed the task you gave above. the POST card did not update, no video out and the result of the floppy stopping is attached. This is likely pointless with the wrong chip. I am going to pull a compatible chip from another motherboard and try again, although I am sure I have done that? The other chip may not be a boot block chip though.

I am learning alot! Thank you

further information was that i am able to read the 28F001BXT, pins 12,13 and 15 give errors, without pin detect i get the attached bin. It looks to be corrupt. I have no boot block chips, so i am looking online for a replacement. Thank you and sorry for wasting your time when its something i had missed. Thank you