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need help identifying 486 board

my ET4000 doesn't say "local bus" anywhere on it. part of the issue seems to be there is so little info on OPTi bus or any of the little used proprietary buses. I mean, I found more information on how there's an alternate dimension where the Beetles never broke up then info on the OPTi bus. how fast is it? what kind of cards were made for it? the only information seems to be that it exists.

anyways. I acquired 8 1mb 30 pin simms and 4 4mb simms from a friend that are being mailed today so when they arrive I'll try them out and hope they work. if not then I guess this board gets thrown into the pile of dead/mysterious boards I never got to work.
 
Just an observation - but you found "433" stuck on it - this made me wonder if it shipped with a 33Mhz processor fitted.
Which raises the question - how does it know what clock cycle to use? Possibly a faster processor or even clearing the CMOS might help.

Just an idea.

433scl/64 - to me I'd guess that to be a 486SX-33 with 64KB cache.
 
SpidersWeb said:
Just an observation - but you found "433" stuck on it - this made me wonder if it shipped with a 33Mhz processor fitted.
Which raises the question - how does it know what clock cycle to use? Possibly a faster processor or even clearing the CMOS might help.

Just an idea.

433scl/64 - to me I'd guess that to be a 486SX-33 with 64KB cache.
Click to expand...

the board is fitted with a socketed crystal oscillator. the current one is 25mhz and is still tied down so I doubt it was changed. I assume you change cpu speed by swapping the oscillator. I have seem several 386 boards that work in this manner but never a 486. The 25mhz 486 I have fitted now came in the same box as this board so I'm assuming it was the CPU fitted.
 
oblivion said:
my ET4000 doesn't say "local bus" anywhere on it. part of the issue seems to be there is so little info on OPTi bus or any of the little used proprietary buses. I mean, I found more information on how there's an alternate dimension where the Beetles never broke up then info on the OPTi bus. how fast is it? what kind of cards were made for it? the only information seems to be that it exists.
Click to expand...

It seems that OPTi was the first to market with their local bus... but then VESA and Intel stole the show by announcing that VLB and PCI would be "coming soon" with much greater industry support, which rendered the OPTi bus DOA. These few ET4000-based video cards may be the only cards to ever use it.
 
Sorry, I got confused with the second poster whipping out another VGA card. I checked the FCC ID. It doesn't state EISA or OLB, but it does at least let us know that your card is made by Chaintech. I found something on the Chaintech website (history section) saying they made a OPTi local bus motherboard in 1992. Since the two items came together, I guess there is a possibility the motherboard is Chaintech too. The quality seems pretty good at least.
 
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Anonymous Coward said:
Sorry, I got confused with the second poster whipping out another VGA card. I checked the FCC ID. It doesn't state EISA or OLB, but it does at least let us know that your card is made by Chaintech. I found something on the Chaintech website (history section) saying they made a OPTi local bus motherboard in 1992. Since the two items came together, I guess there is a possibility the motherboard is Chaintech too. The quality seems pretty good at least.
Click to expand...

ah, thanks. after looking I found some references to a chaintech 433sc motherboard that appeared to take a 486 but not really any information or images. perhaps the 433scl was the variant with a local bus? unfortunately even having a possible name to the board doesn't seem to help find any solid information. hopefully when the RAM arrives I will be able to get a post *NM, found some layouts of the 433SC and it doesn't resemble mine to much*

as for the 33mhz 486 theory...I don't have one as yet. If I get this board running a 33mhz 486 is actually what I want in it but I get the feeling the CPU speed isn't the issue. can anyone clarify about the oscillator? it looks original to me. I remember my 386 had an oscillator but I think it halved whatever it was. for instance the CPU was a amd-40mhz so the oscillator was 80mhz, I wanted to drop it 25mhz for some game compatibility so I just replaced it with a 50mhz crystal and got 25mhz.

the crystal in this board is rated 25mhz. I assumed that made sense with a 486 25mhz running at the full rated speed. do all boards cut the speed in half? if so maybe the board is trying to run the cpu at 12mhz and it doesn't support that?
 
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oblivion said:
on one of the local buses there is a sticker. sticker on expansion slot says "433scl/64k 01177330"

There was a card that came in the same box as this board. I assumed it was EISA but it may go with this board.


it has the same style sticker on the back of the card as the one on the motherboard though that may just be for store inventory or something. though they both have 5062 on the sticker

I tried removing the l2 cache. I also tested the CL isa video card I was using to make sure it was good, it is.

I filled bank 0 with 4 512kb 30 pin RAM chips. I no longer get the 3 beeps error but still no post, just a black screen. maybe the RAM isnt large enough and I need to dig up 4x1mb simms? or the board may be dead. I swapped CPU's with another 25mhz 486sx I had just to be sure and same effect.

*on top of VGA card "03310201-5303 made in taiwan"
Click to expand...

Oh, hey, that VGA has an FCC ID on it, which is actually really helpful. The grantee code on it (IA6) is assigned to Chaintech.
 
I propose the model name 433SCL represents: (4)86 (33)MHZ, (S)iS chipset, (C)ache, (L)ocal Bus. Chaintech has other bards that follow similar naming convention, like 486UCL, which uses a "USAI" chipset. It doesn't really help us with the missing jumper settings and manual problem though. I guess your board is just rare enough that TH99 never had one pass through their hands.

I wouldn't be so concerned about the 25MHz oscillator. It all depends on how the motherboard is setup. For example, the 486 boards I have always want a 50MHz oscillator for running a 486DX-50. There is usually a jumper on most boards that use a a CPU oscillator to set either a 1:1 or 1:2 ratio.
 
Anonymous Coward said:
I propose the model name 433SCL represents: (4)86 (33)MHZ, (S)iS chipset, (C)ache, (L)ocal Bus. Chaintech has other bards that follow similar naming convention, like 486UCL, which uses a "USAI" chipset. It doesn't really help us with the missing jumper settings and manual problem though. I guess your board is just rare enough that TH99 never had one pass through their hands.

I wouldn't be so concerned about the 25MHz oscillator. It all depends on how the motherboard is setup. For example, the 486 boards I have always want a 50MHz oscillator for running a 486DX-50. There is usually a jumper on most boards that use a a CPU oscillator to set either a 1:1 or 1:2 ratio.
Click to expand...

I'll try and acquire a 33mhz 486 and see what happens. The good/odd thing about this board. It has exactly 1 jumper on it. That's seriously it and it's labled. It's for selecting either 486SX or 486DX
 
I don't think getting a 33MHz chip is going to fix your problem. I strongly suspect incorrect or bad memory configuration.

In addition to your CPU type select jumper I can also see black resistor packs near the SRAM which determine the cache size.

I think this board and card are worth hanging onto since they are kind of unique. If it could be restored to working condition it could possibly be worth something one day. For example, IBM PGA cards reportedly sell for $200-300USD, Adlib cards can fall into the same range. Neither has any practical use in retro systems.
 
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oblivion said:
Also any idea what the "cpu upgrade" socket is for.
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That's easy. At those times there was also an 486SX CPU. You could install an 487SX chip in the upgrade socket to add the math coprocessor. That is the official story.

The inofficial story is that this 487SX chip is a complete 486DX CPU. If you plug in that 487SX into the upgrade socket it disables the 486SX completely and does all the activities by itself. But if you now think you can pull out the 486SX from the board you are wrong, the 487SX only starts when the 486SX is present. But there was some trick to fix this, but I don't remember the detail. German c't magazine found all of this out and showed also how to modify the board and run the 487SX in a 486DX board/socket as the only chip.
 
ITS ALIVE! mostly anyways. The issue was indeed RAM and even after getting ceveral 30 pin chips the board was very picky. I was about to give up until I found a set of 4 matching 1MB simms worked. these simms have 3 chips on them each. so now it posts. unfortunately even seeing the BIOS hasn't really shed to much light on things. I decided to be daring and try the suspected OLB tseng but the card would not display which was kinda the main point for me restoring this board. I tried both brown slots and no image. there was also no smoke or horrible noises so maybe the video card is dead, bummer?

looking around the BIOS setup I couldn't find anything special. only unusual thing I saw was the option to enable a Weitek chip.

I know sometimes the MB info is posted at the bottom but I cant make any sense out of the string of numbers

 
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