have you tried swapping out IDE cables?

Yes. I think my mobo is damaged. After hour, after installed on other PC, DOS was broken - again stuck on boot.
I'm trying this on two different hard disks, different cables.

In addition, I noticed the secondary controller don't work. In BIOS disk is detected on secondry master - but on POST screen is not detected. Also cache chips is very hot after couple minutes and cache memory show "none" on POST screen.

Better i'm looking for new motherboard. I write new topic here : AM486DX4-100 - which motherboard

How did you set the partitions on the HDD?

I'm trying also one partition 128MB. Same behavior. Stuck on boot. But only if I install DOS on 486 machine. When i'm install on K6-2 machine, boot fine. But after ~hour and restart stuck again

Santyago wrote on 2023-01-19, 18:40:

After partitioning the hard drive, formatting, setting active partition, mbr and installing DOS, the boot stuck after post screen. No error messages.

so you partion, reboot, format, reboot, set active, reboot, install dos, reboot... after the last one it doesnt boot? how strange. i would do a simple install, aka fdisk /mbr + sys c: and boot into C: with nothing, as a test.

i wonder if its got incorrect size settings lba vs chs or something, and the dos install is overwriting other bits of the disk...

have you tried installing on a 5oomb partition to start with? depending on your disk controller, dos 6 will only work reliably on either 500mb or 2gb per partition.

i'm also trying simple install fdisk /mbr + sys c: - also stuck. But again, only if i'm do it on 486 machine 😀

yes - i'm trying also 500MB .... 128MB .... that same issue

But why if i'm doing on other computer and back hard disk to 486 machine boot fine? But also after hour/two, when i'm reboot - boot stucks again 😒

And this is normal if SRAM chips (cache) is very hot after couple minutes?

I think to buy other mobo, but i'm not found any support AM486DX4-100 (A80486DX4-100SV8B) without doughter regulator board ( AM486DX4-100 - which motherboard ). Maybe I should buy some DX2-80 and other any mobo ?

If the cache chips are getting very hot, they might be bad. If the system is trying to use the cache, that could explain the issues you've been having. Are the chips socketed? It might be a good idea to replace them. If they're soldered, it might be more difficult, especially dealing with the motherboard's ground plane.

Is socketed. Good point I will try remove it and disable in weekend

Van Slanzar de Fanel wrote on 2023-01-20, 14:02:

If the cache chips are getting very hot, they might be bad. If the system is trying to use the cache, that could explain the issues you've been having.

Yes! After replace cache chips all works excellent. THANKS !!!!!!!!