Unbelievable what happened a little while ago!!!

Lately, I've been working on some 486, including an AT Industrial UMC chipset, searching on TRW is the same as a Power Tech MB457, well to make it short, lately (years ago) I had tried to start it with an Intel 486SX25 CPU, unfortunately nothing happened, no post code on the ISA-PCI card (here obviously you can only use ISA), try various RAM both 30 and 72 PIN, an Intel 486DX33 CPU (which I was looking for but still can't find), and try and try again and nothing!

Today I finished cleaning the cache chips of the 486 PCI (Terminator), and I wanted to change CPU to temporarily install the DX33 instead of the AMD DX4-100, I managed to find all the 486 I have, except the DX33, maybe it's in a motherboard, I'll check.

So having a free space on the bench, I take the MB457 one, and I place it ready for a further startup attempt, but first I have to recover an ISA VGA and a RAM, I connect the AT keyboard and ATX-AT adapter (for the power supply), I use an old WD card for the VGA, and for the RAM I take a 70 ns 72 PIN with 8 chips, I thought it was 8 MB, in reality it is 4 MB, it doesn't matter anyway.

So I try to start it's incredible what happened: Codes appear on the post card, and you hear a beep, on the video I have the BIOS screen!!!

But why all this surprise ???

The last time it worked, was 30 years ago, then nothing!

Now I'll try to make some additions, like a controller card for disks, but maybe also the 30 PIN RAM, to have a total of 8 MB, then if it works maybe I'll try with a 72 PIN RAM of 8 or 16 MB, replacing the 4 MB one.

One last problem I'm having is that I'm almost without VGA ISA, unfortunately I've been looking for a Trident (8900) for many years, but the requests are too high, I was looking for this model because it's the same as the one I had in the early 90s, then of course it won't be identical but for me it would be fine in a PC like that, even if originally I had a Cyrix DX2-80 that was quite fast, this SX-25 I don't know but I think it's at the same level as a slightly faster 386DX, even if it has an 8 KB L1 cache, which at least does something, since the Motherboard does not have L2 cache on board.

I started to do a first upgrade, to the MB457 motherboard, I added a controller, unfortunately among my stocks I only have another one the same, they are 16 bit ISA controllers for HDD and FDD, no serial and parallel ports, and anything else 😨 there may be, an old and simple controller for drive A: B: C: D:, so two FDDs and two HDDs, but also in the BIOS there are two FDDs and two HDDs, so if we want to connect other drives, I think it is a must to add a second card (probably?).
For the moment I recovered an old 540 MB HD (approximately) from IBM, years ago I had removed it because after loading DOS and Windows 3. X, the next day it didn't start anymore, it lost the boot files, even if the surface of the disk was ok, without any defective sector, I'll try again and see what happens, I hope 🤞 that the problem was not unsolvable, and that maybe it can be recovered ❤️‍🩹
Since I have the ISA controller, I connect the 1.44 MB floppy player 💾, set the PC from the BIOS because by default there is the 1.2 MB one, I insert a bootable disk with MS-DOS 4.01, and the PC boots, at this point not having other disks at hand, I execute some commands, like Ver or Mem, just to do something.
From what I remember, this controller does not recognize the IDE CF adapter, but maybe I could try to see if the IDE SD one works, in case I would make a bootable disk in an SD memory card.
Finally, I wanted to send the images of the manual to TRW, actually it is a sheet folded in two, very simple, but anyway the card is also very simple, there are not many jumpers, and you can select 4 FSB, 25 33 40 and 50 MHz.
At this point I'll add them here, then if maybe someone can send them, that's fine with me Thanks