Well maybe today it went a little better, at least I spotted where the problem is!!!

We always talk about the SMT-486 Terminator motherboard, what I suspected, was not wrong at all, and having seen codes sometimes, made me think that somehow the board was ready to start, but something prevented it.

I had a doubt that some jumpers were not correct, there are really many, and it is not well explained what they do (?), but they can be considered correct, even if strangely between a DX-33 CPU is a DX4-100, the only different thing looks like the Voltage, I don't know maybe this card has an automatic recognition of the multi, or are the CPUs that are able to select it by default, I didn't look for info about it, so I keep the selections found in the manual for good, and I hope they didn't get confused before going to print.

The points that are most suspicious for me are the RAM banks and the CPU Socket, I tried to move the RAM from one bench to another, and I got nothing, no start sign, so I decide to try to remove and put the CPU back, here there is something positive, sometimes I see the code C0 —, this means that something started, but it failed to continue.

After several attempts, it gets to display a couple of 0b 0A codes, at that point I don't know, I was trying to understand if it was blocked, but shortly after surprise !!!

In the video there is the BIOS screen, which asks to press F1 or Delete (or F2?), I press F1 and it continues, of course without any drive connected, I can't do anything!

I restart and enter the BIOS, it's quite simple, but I would say adequate compared to other 486, and it's not essential, obviously its limits, are largely due to the type of PC, but from what I see, you can optimize some items to make it a little faster, in this regard, only after turning it off, I realized that the L2 cache is 0 KB, while on board there are 4 chips for a total of 256 KB, unfortunately I couldn't do much else, because after a few minutes of operation, it crashed, and not It was possible to restart it, I'll try again ️ as soon as it cools down, and for the record, the CPU was an Intel 80486 DX33, and the VGA was ISA Cirrus Logic.

Although I still haven't solved it, some of the problems that remain, it seems that with the use they get better, I got to do the Phil's benches, and not only those, I ran the usual diagnostics, in short, it worked without problems for quite a while!

Which motherboard? The SMT-486 Terminator II, with Intel 80486DX-33, the RAM was initially only 4 MB, but after seeing that some of Phil's benches did not work, probably because there was not enough memory, I replaced the RAM with another 8 MB EDO, later I wanted to add a second 8 MB EDO RAM, but unfortunately it no longer managed to start, here I think I will have to remove and reinsert the CPU once again ️, usually this works and in the luckiest cases, it works very well.

Well, but it's not really correct, because when the PC works, the L2 cache doesn't work, you think there's no problem with the chips or HW, maybe it depends on the jumpers, those of the capacity are correct, but those of the CPU instead are not clear, and correspond to the UMC CPUs, maybe you should try different settings, like those of the AMD CPUs, but unfortunately I don't have an AMD DX33, this makes me think of changing the CPU again and going to a 486 DX2, just to see if the L2 cache works, or not.

Then, once full functionality is reached, I should redo some benches, and start the various upgrades, yes because there is the possibility of putting more RAM, and adding a sound card, plus other cards, not many but because we only have three PCI slots, one already occupied by the Miro PCI with 1 MB S3 chip (video card), maybe here it would be the case to use an ISA sound card, and maybe a PCI card with USB ports, with this I saw recently, that it is possible to have three floppy players, two connected directly to the motherboard, the third 3.5" is Connected via adapter to the internal USB port, although for access and use, you need DOS drivers, with Windows 98SE instead no problem.

This FD3.5”-USB adapter, I think it is very useful in PCs that do not have it (the floppy), or even in motherboards that do not have the 34 PIN port for connecting to Floppy, it is also very convenient, if we have to move the files, but for this very reason recently, I bypassed the limits of the 1.44 MB disks, using the null-modem cable and the LapLink program, they also exist in USB version, certainly faster than the parallel and serial ones.

The current performance looking at the image of the bench that I put, is about 10 times lower than a P200, I think that the value with the L2 cache working, may be different but the considerable distance would remain, the only way to get closer, would be the change of CPU with a fast AMD, because unfortunately Intel stopped at 100 MHz, the competition instead went further, for example the 5x86-133 P75, reaches performance similar to a Pentium 75, on the other hand you notice that the 486 is almost twice as fast, in short, to reach the Pentium 200, you would need a 486 of about 350 MHz!!!

With the SMT-486 Terminator II and Intel 80486DX-33 motherboard, I make some slight progress, while before to get to the BIOS screen, you had to remove and reinsert the CPU, now even after a few hours, it manages to work even after it was turned off, it seems a not very important thing, but it is a very small progress, on the other hand, there is a stability not so good, sometimes it crashes quite soon, other times it works for a while, but at a certain point it freezes anyway!!!

Of course, that the Socket problem is not completely solved (?), or there is something else that causes problems, a suspicion is on the jumpers, maybe they are not set correctly, but this CPU still manages to start and work, another problem that I have not yet understood well, is that of the L2 cache on board not detected, maybe it is somehow connected to the jumper problem, or it could be a RTC problem, yes because I discovered that although the battery is charged, it does not keep the changes to the BIOS in memory, and after the shutdown in a short time Go back to the default settings, this is a third problem to solve!!!

All in all for me they are special satisfactions, having literally resurrected this MB 486 PCI was important, because it filled the gap that had been created, when the family created it exactly I don't know, I learned it quite recently, when by now the price of these motherboards had risen a lot, however that was a fairly similar motherboard (BEK P405), it had an extra RAM and PCI slot.

The current CPU, an Intel 80486DX-33 is temporary, the final one will be at least 100 MHz, the starting point would be an AMD DX4-100, but there are other CPUs that I could use, I could for example exchange it with the Intel DX4-100, or staying in AMD I would have these:

DX2-80, DX4-120, 5X86-133 P75

I wouldn't use Cyrix or ST equivalents here, although I don't have any of these other than the DX2-80. Unfortunately I don't have the Pentium Overdrive (for 486), which exists in two versions 63 and 83 MHz, it would be interesting to understand if the 83 MHz is comparable to a P75 (even in overclock at 83 MHz with FSB 55), but I imagine that the S.5 is a little faster with the same frequency.

I ran other benchmarks, and some diagnostics, one provided interesting information, that is, what SMT means, you can read it clearly, personally I would not have imagined it.