Your hot-433 BIOS is Award instead of AMI WinBIOS? And it's from 2001? Interesting...

I don't know much about the BIOS modification utilities but maybe a checksum is not being recalculated correctly? Do one of those minor edits that shouldn't bother anything and then compare the resulting binary with the original one in a hex editor. Something must be different if it doesn't boot anymore.

If the BIOS is uncompressed or the utility can decompress it, it could be disassembled to find the test that fails. Search for the diagnostic code that corresponds to the error being written to port $80.

Yes, I tested several different Award BIOS images. Like these ones here:

I tested the 433WIE10.BIN from 1995
the 2A4X5H21C-00.rom from 2001 (which came with the Board I bought from ebay)

I will upload all images here, so others can make use of them and maybe help me too.

The problem is: I can not add anything to the Images. I can change some of them e.g. by using modbin to change default settings, PCI mappings, text etc. no problem.
But I can not add any option rom or other stuff using cbrom. It either tells me that there is no space available (but the images only use about 60% of the available space, like 70-80KB), or it does the job, without complaining, but the image fails to boot, even though it looks nice, all checksums are good.

I am stuck here. If there is anyone with a HOT-433 out there please help me. I only would like to be able to add anything to the image, like an ACPI table or a PCI option rom etc.

I couldn't extract your .rar for some reason, but I downloaded the 433WIE10 file from the other site and it works in my board even though it is a rev 4.0. I tried to monkey with it using different versions of cbrom but it seems to be misreading something. Saying that the first module is 16KB but has a compressed size of 64KB with -20KB space remaining... doesn't make too much sense. I'll try a different utility later and see if there are any clues forthcoming.

Bakemono, thank you for testing the BIOS file.

Here is a direct download link to the file you could not open. The 2A4X5H21C-00 from May 2001

http://kernfusion.at/shuttle_2001_01_05_hot_4 … A4X5H21C-00.rom

This should work very well with your Board and is my favourite BIOS for the HOT433 since it features a modern 4.51PG Award base with lots of options, large HDD support, up to 127 GB and direct boot from CDROM and even AddIn cards.

I tried to put options roms/ ACPI tables / pictures etc. in it, but no luck at all. It does not work, even if I just use cbrom to extract and re-integrate a component.
Maybe you have more luck. Even if you don´t, you got yourself test newest BIOS for this board out there.

When inserting an option ROM into that BIOS with cbrom 220 a 1KB chunk of code at $1D000 disappears in the modified ROM. Considering that it says Award Decompression Bios at the beginning, I'm guessing it's important. Maybe patching that back in will fix it?

The older BIOS can be opened with modbin 4.5 but I don't see any choice for inserting tables/pictures/etc just tweaking defaults and hardware settings.

Whoa, the plan worked 😀

I used cbrom220 with the /isa switch to insert a copy of XT-IDE (just for testing purposes). Then I used a hex editor to copy the block from $1D000-$1DB20 from the original file into the modified file. Programmed that into the EEPROM and it powered up, and the embedded XT-IDE worked as well. (Somehow the ol' Dallas chip even managed to remember the CMOS settings from yesterday)

Oddly enough, my board crashes after POST if I have the L2 cache enabled with this 2001 BIOS (at 60MHz FSB anyway). But at the same time, enabling the EDO option causes memory performance to skyrocket to unheard of levels for a socket 3 board (75MB/sec)

I tried it myself, and yes, it works flawlessly. Excellent job bakemono 😅

Oddly enough, my board crashes after POST if I have the L2 cache enabled with this 2001 BIOS (at 60MHz FSB anyway). But at the same time, enabling the EDO option causes memory performance to skyrocket to unheard of levels for a socket 3 board (75MB/sec)

That´s why I use the Rev.3 supporting up to 1MB cache. Gives the ability to install more ram, which is in cacheable range I guess. But 75MB/sec is impressive. I get 40 MB/s max (at memtest 5.01) using EDO ECC memory. and only at 33Mhz FSB, so kinda boring...
The ECC is important since it´s a productive system. I use it to flash ISA GPS receiver cards to support the new Galileo time system for more precision, and put them back into the HP reference Ceasium "atomic" clocks.

After all I try to install Windows 7 on the 486 board (yes, really) using a Pentium Overdrive CPU and by putting an ACPI table to the BIOS since Win7 requires it. The stupid HP update tool for the GPS cards only works with Win7 and newer (it´s typically used with more recent cards and the ancient ones are just still in there, but supported).
Tried socket 7 boards with ISA slots, but the cards / updater don´t like them for unknown reasons.

If anyone can help with putting Win7 on a PC without native ACPI support, please let me know. I don´t exactly know how ACPI works, especially since there are boards out there which receive "ACPI support" just by BIOS update, e.g. some early socket 5/7 boards. I always thought a physical ACPI chip had to be installed for it to work.