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Uknown UMC 486 board

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First post, by JaNoZ

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Hi Guys,

I have this board here that is running my am5x86 at 150Mhz 3x50 and running quake on S3 Trio64V+ pci card 16FPS demo1 2x8MB FPM 60ns and 256K UMC 15ns cache in WB mode at 2-1-1-1

Now i had this board for some time, and i heard that there is more FSB jumpering to do, can anyone tell me the settings.

Also is someone familliar with this board, what type it is brand etc.
Who knows where to get some speedy FPM ram as it seems only this type of ram is keeping up my tightest ram timings at 50fsb, if i take a stick with thicker ram or use more than memtest will not be succes and quake wil crash back, but i love tight timings also to keep the 16FPS alive.

I would like to try to do 180 or 200mhz, i have 6 am5x86's

Thanks,

Reply 1 of 11, by leileilol

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Looks like a PCChips M915i. Extremely similar layout there

apsosig.png
long live PCem

Reply 2 of 11, by JaNoZ

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Ok, PCchips M915 that indeed seems to be it, but i cannot find any jumpering info for this type with google.
And I would like to upgrade cache to 512k or 1M, does anyone has any jumper info for this board also for cpu type's.

Or anyone here has an original manual.

I have some original 386 and 486 manuals i will share them with you.
Also looking for some information regarding this 486 terminator board.
http://www.ebay.nl/itm/190674522311?ssPageNam … 984.m1423.l2649

I have one without jumper info and do not like to spend this much to get a copy of the manual.

Reply 3 of 11, by luckybob

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YAY!!! I happen to have that EXACT board! except my pci slots are black. ^.^
Pcchips M915i

Mine has a non-removable bios chip and I've been wanting to replace it for quite a while now. Yours looks removable! That being said, I would LOVE to see if your cache is working or not. If it works, I'd pay to have a copy of your bios. More info on the board can be had here: http://th2chips.freeservers.com/m915/index.html

the bios is actually very smart for a 486. at least on mine. all you need to do is set the fsb speed and its ready to go. Jumper 6, 7 & 8. set tehm to 33mhz and boot the board should automatically set the cpu to 133mhz. you NEED a heatsink before you do anything. And if you would be so kind as to benchmark the board with speedsys 4.78 that will tell us if the cache is working. download speedsys here: download.php?id=5601

It is a mistake to think you can solve any major problems just with potatoes.

Reply 4 of 11, by leileilol

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luckybob wrote:

YAY!!! I happen to have that EXACT board!

Check the revision number in the corner. His is V2.1

apsosig.png
long live PCem

Reply 5 of 11, by luckybob

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leileilol wrote:
luckybob wrote:

YAY!!! I happen to have that EXACT board!

Check the revision number in the corner. His is V2.1

I didn't look at that. But once I did, both of our boards are rev 2.1. So the difference between our boards is quite literally, mine has black pci slots, and his might have working cache.

It is a mistake to think you can solve any major problems just with potatoes.

Reply 6 of 11, by 3DfxNerd

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oh god no. my 486 has a similar motherboard (it has 32 pin SIMM slots and 72 pin fast page SIMM slots) its made by PCCHIPS and has got to be the crappiest board I ever saw (aside from any acer newer than 2002, they are worse) there is a sticker over the chipset that says " Write back Cache!" and indeed, the cache is about as real as a cardboard CPU.

the board will randomly die and start working later on. I only keep it because its the only 486 board I have.
if mine worked correctly, it would be a decent board.

Insert creative signature here.

Reply 8 of 11, by JaNoZ

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Luckyob, i see yours has also a Secondray ide port 😀

Luckybob, you have realy nice Black VLB and PCI slots.
I have several white ISA boards but never seen this.
btw you can install a removeable socket for you bios if needed.

When i get some time, within some weeks i will readout the bios rom for free of course and see what version i have. I think it is a pre 9151108s version as i have seen you guys posted here.
Does someone know what type is in there, should be a 1Megabit but i do not really like to remove the sticker.

But i like the bios windows interface, it something different for back then.

As for the cache i should be 100% sure it is working, but i have spare sram 15ns ISSI WINBOND Hyundai etc.
This runs really well at 2-1-1-1 at 50FSB.
I have a sis496 zida 4dps board and my5x86 at 133 was sluggish and has also 256Kb cache, GTA ran like cr@p, and not to mention Quake, unplayable.(orignal am5x86 config and WB cache)

This board however runs so much faster as if i were running 50% extra clock at same settings. But will have to look into jumpering as i cant even remember if it is running in WB mode or WT.
It is exactly running the same FPS with the same card as my socket 4 P66's so i believe then at 150mhz the amd FPU is finally matching up with intel Pentium at 66Mhz.
But Starcraft run so much better on the higher clocked 486

Last edited by JaNoZ on 2012-10-10, 20:15. Edited 3 times in total.

Reply 9 of 11, by JaNoZ

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@ 3dfxnerd

Maybe it is easy to say be me because i do soldering each and every day but, if i were you i would change all capacitors also from your (if it is still original AT PSU) power supply.
Then remove all fake cache shit and place sockets on them and install real sram, remove the soldered loops for cache settings and install pinned jumpers., install a bigger heatsink on the power regulator. (that is still on my list also, only time i need)

If you can solder you can do it, if you were my neighbour i would do it for you for free.
But i think your far away so start you soldering skills on scrappy boards P4 boards or whatever and try to improve before attempting to do your 486 board.
You can screw up easy, skills are sadly enough some requirement if you do no want to damage your PCB beyond repair.

Reply 10 of 11, by 3DfxNerd

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I have soldered before on a few P4 boards with bad caps, and I was successful each time, except for my first attempt. I just don't want to mess with it too much even if it is junk, but its vintage junk, the world can't afford to lose another 486.

it is important to not get the PCB too hot, or the traces can lift, thats no fun to repair, 🤣.

Insert creative signature here.

Reply 11 of 11, by JaNoZ

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I have to say that it is easy to solder on older boards (lead solder) and heat should be around 380 celcius hot air on the backside of the board, but the board needs to be steady and not be disturbed like tapping to it parts can move.
Eventually you can pull out gently the ic or the plastic holder, without damage.
For the ram, it it is a fake waste you could cut gently all the legs and pull all loose legs out together when heating them with iron and solder, and removing the waste solder in the hole with a suck or if the board is still hot enough with solder wick.