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Looking to find some L2 cache for my 486

T

Tr3vor

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Feb 7, 2012
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Jerome, ID
I was looking around inside my 486 machine when I took a closer look at the cache area of my motherboard. I saw the jumpers and they were set to 256k of L2 cache. I thought that maybe the empty sockets were for more and that 256k was built in or something, but when I turned on the computer and looked around the bios menu, It said that it had none. I'm surprised that the computer wasn't throwing codes at me for having the wrong amount of cache set or something, but maybe there is another jumper to turn it off or maybe it detects it automatically. I don't know.

So I want to get some cache in this machine, since from what I've heard, not having L2 cache in a 486 that's around 25 to 33mhz makes it run like a 386. but I don't know what to look for. At least this motherboard I have lets you put cache in it, unlike those PC Chips boards I've heard of.

I'm new to this so I have a few questions:

1. cache is DRAM, right?
2. Do motherboards take certain DRAM chips depending on the motherboard, or can they take any if the chips have the right specs?
3. Can you help me find the stuff I'm looking for?

If it matters, my motherboard is a "PWA-IH4077C BD". next to this model number (I think that's what that is.) is this: "ASSY NO:4116328000XX-R02", but I think that's a serial number. The sockets also have 28 pins. I've had no luck looking for the manual or anything for the motherboard, eventually I got to some weird foreign sites and called it quits.

Thanks for the help in advance.
 
Cache is typically SRAM; often it's standard-package DIP chips, though sometimes it's proprietary SIMMs. The best way to know is to find documentation for the board; if you don't have a manual, TULARC is your best friend, but if it comes to it SRAM is cheap enough that you can always take a chance on just buying some.
 
This motherboard uses DIP chips, and not SIMMs.

There are 9 DIP sockets on the board, so 256k/9= 28.4444k chips? how does that work? Is that for parity and it takes 32k sram chips? I might go and buy some chips, as they seem cheap enough just to try it.

EDIT: What is a good access time for L2 cache, since I'm seeing them from like 70ns to 20ns.
 
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I think you have to divide by 8: 8 x 32K chips is 256K and then there is one TAG RAM chip. I'd go with the 20 or 15ns chips. Cache shouldn't be 70ns, that's normal RAM speed (?).
 
Do you think that I need to have that TAG RAM chip, or will it do without? If SRAM chips come in packages of 8, it would be a waste to buy 2.
 
#1 if the sockets are 28 pins, and there are NINE of them, then your maximum cache is 256kb.
#2 if the board/bios finds empty cache sockets, or if there is something wrong with the cache, then it just disables the cache.
#3 15ns is the most common speed to get. Unless you are doing weird overclocking, you wont need faster. 12 and 10 ns exist but are usually very expensive.
#4 I'd probably buy 9 of these: http://www.ebay.com/itm/200872617044
#5 download the freeware dos program cachechk (google it) It will test your cache for you.
#6 A LOT of 486 era boards suffered from fake cache. Older 486's were usually okay, but by the time the dx4-100 came around, it got real nasty. If you see anything called "shadow ram" then dont even bother populating the cache on the board.
 
Considering this computer is from around 1993, it might be fake, but I don't see any "PC Chips" or "Write-Back Cache" or any of that hoopla on the motherboard. the only place I see "Shadow" is in the bios for video and bios shadowing, so I'm guessing this board is not one of those.

Also, the chipset is UMC if that matters. and the chips do not have stickers or all that on them.
 
No. Mine has:

8 30 Pin Simm slots
the cache sockets are in 2 rows facing the other way
the kbd and bios chips are next to each other
the jumpers are in different positions
there is no integrated FDC or IDE, I have a multi I/O card for that.
 
Tr3vor said:
Do you think that I need to have that TAG RAM chip, or will it do without? If SRAM chips come in packages of 8, it would be a waste to buy 2.
Click to expand...

The TAG chip is not optional. It is required. In fact depending on the mainboard it might need a 16Kx8 or a 32Kx8 TAG in order to address 8 32Kx8 cache chips for a 256K L2 cache
 
orion24 said:
The TAG chip is not optional. It is required. In fact depending on the mainboard it might need a 16Kx8 or a 32Kx8 TAG in order to address 8 32Kx8 cache chips for a 256K L2 cache
Click to expand...

Well I ordered 2 32K x 8 packages, hopefully that TAG is a 32K chip.

I'll update when I get the stuff and see how it works.

Thanks for the help :D
 
I was looking some stuff up and found this neat website: http://redhill.net.au/b/b-bad.html

it says that usually if there isn't cache on a motherboard and it is enabled in the bios, the computer will hang, so to get around this cheapo computer makers altered the bios to force the cache off, no matter the setting on the bios.

so if mine doesn't automatically disable it if there isn't any in there, and I'm stuck with the cache off, maybe I could replace the bios, since its socketed.
 
Tr3vor said:
I was looking some stuff up and found this neat website: http://redhill.net.au/b/b-bad.html

it says that usually if there isn't cache on a motherboard and it is enabled in the bios, the computer will hang, so to get around this cheapo computer makers altered the bios to force the cache off, no matter the setting on the bios.

so if mine doesn't automatically disable it if there isn't any in there, and I'm stuck with the cache off, maybe I could replace the bios, since its socketed.
Click to expand...

If it hangs or not, will depend on the board and the BIOS. Since you ordered them it'll be easy to tell the difference with a benchmark tool like 3DBench or NSSI. But the L2 cache in a 486 won't make it that much faster for one to tell without running the benchmarks.

Personally I don't think you have a "fake" board. That board of yours came with the cache banks empty. Usually the fake cache boards were having them full with fake chips and then had modified BIOS versions to incorrectly display. It doesn't make any sense to have anything fake since the board clearly has no L2 cache at all and it "doesn't hide it".

Also the cache memory in these boards is usually defined primary by jumpers and only a few secondary options, mainly speed-related, are configured from the BIOS. If your board doesn't have "prints" on it to specify how to configure the jumpers, then you need to look for it in the internet archive and find how to do that. Otherwise it might not work.
 
Check this site to see if it helps with your motherboard. It uses the numbers at the bottom of the POST screen to identify the manufacturer and model number of the board.

If it helps, I bought this as my TAG chip.
 
Yaaaaaaaaay. I'm dumb.

I guess that 32k "x8" doesn't mean they come in packs of 8.... -.-

I now have 2 chips of 32Kx8 . this is swell.
 
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