Could cache be disabled somewhere...turbo button turned off?

clueless1 wrote:

Could cache be disabled somewhere...turbo button turned off?

Preluder wrote:

It's running on a PCChips board with the UMC chipset

I wonder if this could be one of the infamous fake cache PC Chips 486 boards... Maybe a pic of the board itself might help?

In the bios the "Internal Cache" is Enabled, other than that there are no more options.
The turbo button jumpers are bridged, so it's always on.

Heres' a pic of the board:

In mine the chipset says BA1915 instead of RC1047, but the rest looks the same.

After the POST screen, but before the "Starting MS-DOS" message, PCs usually show a bunch of information. Does it say anything about the amount of cache installed?

Btw I'm pretty sure "Internal cache" means the processor's built in L1 cache. You could also try something like CACHECHK to check your cache.

Preluder wrote:

In the bios the "Internal Cache" is Enabled, other than that there are no more options. The turbo button jumpers are bridged, so […]
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In the bios the "Internal Cache" is Enabled, other than that there are no more options.
The turbo button jumpers are bridged, so it's always on.

Heres' a pic of the board:

In mine the chipset says BA1915 instead of RC1047, but the rest looks the same.

I can't read the print on the PCB to check if the CPU (and the rest of the board) is jumpered correctly.
At first glance your cache chips seem like real ones, one of them seems socketed, which is a good sign (though of course no 100% guarantee)

And agreed with using a program like CACHECHK 😀

edit:

Preluder wrote:

In mine the chipset says BA1915 instead of RC1047, but the rest looks the same.

Wait, this isn't a pic of your actual board then?

Well here's a pic of my actual board, at least the part that can be seen. The rest is covered in wires and cards.

It says "256kb internal cache" at start, but cachechk said "this machine does not seem to have any cache"

And this is the mobo info and manual, all the jumpers set up according to this:

http://motherboards.mbarron.net/models/486vlb3/m912v17.htm

Perhaps the soldered cache is fake?

I would still try to remove the jumper bridging the turbo button header as a Speedsys CPU benchmark result of 10 is way too low for a DX4-100 even without L2 cache. On some boards "turbo on" is the "fast" setting and on other boards it's the "slow" setting.

Maybe a trivial subject since you already checked that, but do you have any "startup speed" kind of option in your BIOS settings? There are boards from that era which has this option and when set to "low" starts as turbo button is in low speed status.

"256KB Internal Cache" is kind of weird (nothing has that much "internal" -L1- cache during that period of time, not even close) so looks like a bogus statement. Your board might be a fake cache/BIOS modded PCChips.

Yeah, that board definitely reeks of PC Chips - the UMC stickers on the chipset tell all. Also the "WRITE BACK" labels on the cache chips are a pretty telling sign that they are fake.
http://redhill.net.au/b/b-bad.html

tayyare wrote:

Maybe a trivial subject since you already checked that, but do you have any "startup speed" kind of option in your BIOS settings? There are boards from that era which has this option and when set to "low" starts as turbo button is in low speed status.

"256KB Internal Cache" is kind of weird (nothing has that much "internal" -L1- cache during that period of time, not even close) so looks like a bogus statement. Your board might be a fake cache/BIOS modded PCChips.

Well it actually says "256kb cache enabled" no matter what.
Just checked the link for the pc-crap boards, and well, looks like it's one of those... but the UMC chip is still an UMC chip! 😀

Let's see what's under these two:

Bingo, still an UMC chip? 😊

Not this one:

BIOS soldered to the board:

And fake cache?

Yes those cache chips are fake!

The board should still not be that slow in the Speedsys benchmark.

I'm confused. On earlier pictures it looks like you have socketed, 32-pin, 15ns SRAM with a 28-pin TAG. On these latest ones, it's soldered onto the board. Were the previous pics just examples you found? The soldered "write back" cache does seem pretty suspect TBH...

johnnynismo wrote:

I'm confused. On earlier pictures it looks like you have socketed, 32-pin, 15ns SRAM with a 28-pin TAG. On these latest ones, it's soldered onto the board. Were the previous pics just examples you found?

Yes he did, here's the source: http://motherboards.mbarron.net/models/486vlb3/m912v17p.jpg

You know....this really makes me appreciate tech journalism. If we had had PCPer, The Tech Report, Anandtech, and all the others like them manufacturers never would have been able to screw people over with FAKE CACHE! Duping the public is much harder to do nowadays.

Preluder, I hope you find another 486 mobo soon. I've run across a few appropriately priced ones on eBay so I'm sure you can find something. I even found a set of 32-pin SRAM with TAG to upgrade my Packard Bell Legend 125 from 128k to 256k just this morning so there's still hope. GOODLUCK!

(interesting side-note...I discovered the hard way that 128k of L2 cannot cache 36MB of RAM. I installed Windows 98SE on it and it fell on its face!)

Are the traces bogus or the board actually supports cache? If you are up to it you could solder sockets there and put real cache chips.

The picture comparison does look iffy in the second one, looks like the infamous black plastic with metal legs instead of real cache, no sockets anymore, no jumpers to the right of the cpu socket just soldered wire links unlike the previous image and several umc chips with sticky labels - makes me want to go check my own boards now as I have several pc chips models!

Well, I've got this thing real cheap anyway, came with Trident VGA card, a controller board, both floppy drives (none of them worked), all within the case, including a Cx486DX2-66 processor, all for less than $20.

I've added the EDO RAM (16mb), my old Sound Blaster AWE32, a better controller board, 6gb HDD and a 15" SVGA SyncMaster CRT monitor (stuff I've had kept from older PCs).
The Intel 486DX4-100 came afterwards, got it for $20 bucks.

Found this mobo, MV035 OPTi, it has all the features I'm looking for, including an AMD 486DX2-66 all for less than $50. Just need to add the battery and BIOS from the other board and should be good to go.

Two things everyone seems to be ignoring:

1. cachecheck is reporting "this machine doesn't seem to have any cache" witch means the cpu's l1 cache is either turned off or not working, otherwise cachecheck wold say "this machine has one level of cache"

2. you seem to be running the cpu without a heatsink or fan. The 486 dx4 REQUIRES a heatsink at least.

Well it didn't really had time to heat up since I've been doing the tests and it's performance is at 1/3 of it's capacity. I've seen a lot of these without heatsink or fan, I have a couple of spares to use on it anyway.

Right now I'll see if that mobo I've found could turn out to be useful, not sure if the BIOS from the pc-chips board will work since it might be modified to run without cache.