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486 motherboard cache chips - Where to get these days?

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Manny Bothans

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Joined
Aug 15, 2015
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15
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New Jersey
Hi all,

Cleaning out the basement, managed to cobble together from spare parts what would have been an uber 486 system back in the day -

  • AMD 5x86 133MHz
  • 128MB FPM RAM
  • AOpen AP43 Motherboard
  • Diamond Stealth III S540 32MB Savage4 PCI
  • D-Link 10/100 PCI NIC
  • Promise Ultra66 PCI ATA Controller
  • WD Black 80GB HDD
  • Lite-On DVD/CDRW Drive
  • Iomega Zip100 ATAPI Drive
  • Soundblaster AWE32 w/ 16MB
It was actually a lot of fun getting it all to work together...

Anyways, the AOpen AP43 motherboard only has 256k cache and I'd like to bump it to 512k. Looking at the motherboard jumpers, it appears to be 32Kb x 8 x 8pcs with a 16Kbx8 TAG SRAM.

Assuming I can re-purpose one of the 32Kb chips as TAG SRAM, does anyone know of a good source to get 64Kb x 8 SRAM chips these days?

Thanks!
 
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I'd like to know too. I have the same board and am thinking of using 128MB of RAM with 512K cache

Can you read the part number of the cache chips? If not, I *might* be able to read them off mine
 
I've bought lots of rare and obsolete parts from Aliexpress, where I didn't receive any goods I got a refund. Where I got some faulty parts I either got a refund or replacements sent.
There are more dodgy sellers there than ebay but as long as You are on the ball, You won't lose a cent.

They do have cache chips for old motherboards there, but You need the proper part number to enter in their search bar, otherwise its hard to find anything.

Recently I bought an AMD 5x86 133 cpu, and there are sellers with heaps of 80's era parts, like 8086, 8088, 80286, FPU's like 80287, etc.

some examples

http://www.aliexpress.com/w/wholesa...pe=price_asc&shipCountry=au&SearchText=d80287
http://www.aliexpress.com/wholesale?catId=0&initiative_id=SB_20150823215458&SearchText=mos+6502

cache chips http://www.aliexpress.com/wholesale?catId=0&initiative_id=SB_20150823215635&SearchText=um61256k-15
 
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On a side note: While these cache chips - fake or not - might be a nice collectors piece they are barely as usable as you may think. The performance difference between having proper L2 cache and not having L2 cache at all on a 486 motherboard is between 5 and 10 % for normal applications and games. And I am talking about "proper" L2 cache, not the fake chips as they were pretty common in that era. So cool for bragging, but for practical approaches barely any difference at all.
 
kyodai said:
On a side note: While these cache chips - fake or not - might be a nice collectors piece they are barely as usable as you may think. The performance difference between having proper L2 cache and not having L2 cache at all on a 486 motherboard is between 5 and 10 % for normal applications and games. And I am talking about "proper" L2 cache, not the fake chips as they were pretty common in that era. So cool for bragging, but for practical approaches barely any difference at all.
Click to expand...

Your L2 must be broken or something. The difference between L2 off and on is between 40 and 100+% difference IME
 
Okay, finally got around to taking pics of the cache my AP43 -

8CTyhQv.jpg


So nine UMC UM61m256K-15 chips, which means my TAG is already 32Kb x 8.
 
Yup, it looks like the parts I need are either UMC UM61512AK or Winbond W24512AK. Will give Aliexpress a shot, thanks Imperious!

(And, yes, I do realize how silly this is to do...)
 
I bought these for my 486dx2 machine:
http://www.ebay.com/itm/390838004312?_trksid=p2057872.m2749.l2649&ssPageName=STRK:MEBIDX:IT

I upgraded from 128kb to 256kb. On my board, I have two banks. I could fill up one bank to 512kb using 128k chips. Or, I could fill both banks using 32k chips to get 256k. It is actually faster to use the 256kb configuration in my case: I have two banks of RAM, and it seems that one bank of cache corresponds to one bank of RAM. So I could have 512kb cache on one bank of RAM, or 128kb cache on both banks of RAM.

At least this SEEMS to be how it works, from my performance testing. Due to a rather strange configuration on my MB, one bank (0) of RAM has 4mb (4x1mb 30pin), and one bank (1) has 32mb (1x32mb 72pin). I *must* fill bank 0 before using bank 1.

If I put in 128kb cache in one cache bank, there is an immediate drop in performance past the first 4mb of memory addresses. The upper 32mb does not get any benefit from the cache! But then if I put in 128kb cache in the second bank, the upper 32mb is cached and has performance equal to the first 4mb.

Of course, I would like to have 256kb in both banks, but the MB does not support it.

Just FYI in case your board might be the same way! :)
 
Manny Bothans said:
Yup, it looks like the parts I need are either UMC UM61512AK or Winbond W24512AK. Will give Aliexpress a shot, thanks Imperious!

(And, yes, I do realize how silly this is to do...)
Click to expand...

Will Cypress CY7C199CN 15ns 32K x 8 SRAM parts work for you?
http://www.cypress.com/?docID=48466

You can buy CY7C199CN-15PXC parts brand new from Mouser for $2 each, or $1.82 each if you buy 10.

Oops, nevermind. I was looking at the picture of the UM61256K 32KB parts and didn't notice that you said you are looking for UM61512AK 64KB parts.
 
smeezekitty said:
The board definitely supports 512K. I have the original manual
Click to expand...

Mine does too, but what I am saying is that it may not support it in both banks. On my board I can do 128kb in two banks for a total of 256kb, or 512kb in one bank only. Can you do 256kb in both banks? Maybe so, since you must have a newer board (PCI)! :)
 
cmc said:
Mine does too, but what I am saying is that it may not support it in both banks. On my board I can do 128kb in two banks for a total of 256kb, or 512kb in one bank only. Can you do 256kb in both banks? Maybe so, since you must have a newer board (PCI)! :)
Click to expand...

I checked the manual and it supports 512K in single bank and double bank.
 
smeezekitty said:
Your L2 must be broken or something. The difference between L2 off and on is between 40 and 100+% difference IME
Click to expand...


What board are you using? If the L2 cache gives such a boost then your board probably has some real RAM performance problem. I ran several benchmarks on a PC Chips M919 with an AMD DX4 133 and a "real" 256KB L2 cache - that makes around somewhere between 5 and 10% difference in overall performance.
 
gekaufman said:
In the US, try www.unicornelectronics.com

In China, try www.utsource.net

Much of the IC's from China are used, remarked, counterfeit etc but in general I've had good luck with UTSource.
- Gary
Click to expand...

I've had good luck with UTSOURCE as well, recently purchased some UM6526N Video chips for an NTSC Atari 2600 I have,
worked perfectly, and I couldn't find them anywhere else aside from Best Electronics in the USA, which equals very high shipping prices
to Australia.
Try UTSOURCE.NET if the Ebay store doesn't give any results.

I did get some fake c64 sids from them once, but got a refund via Ebay. Buy through Ebay if You can.
 
So I'm kind of new to this and I need some help. I recently bought a Digital VenturisFP 466 of ebay. Here is the listing if anyone is interested.
Anyway, thanks to Caluser2000 I was able to dl a pdf of the system spec for it. Turns out it has no L2 cache installed. Now I'm having a devil of a time trying to track these things down. If I read the manual correctly this board takes 128k 32k x 8 28 pin sram chips. Now maybe I'm reading it wrong and that could be true but these chips are ****ing unicorns guys...... they don't exist. I've been googling for days and still come up dry.


Here is a pic of the manual. Like I said I might be reading it wrong so if I am please let me know. Any help would be greatly appreciated.:smile:
Any chance you guys know where to find them because I'm tapped.

 
Nobody really sells them because generally they have been thrown out with a part or are currently installed in a part.
The easy trick is just to buy dead or random 486 boards and harvest.
 
bbhaag said:
If I read the manual correctly this board takes 128k 32k x 8 28 pin sram chips. Now maybe I'm reading it wrong and that could be true but these chips are ****ing unicorns guys...... they don't exist. I've been googling for days and still come up dry.
Click to expand...

Are you possibly confused looking for a 32k x 8 SRAM that is described as a 128k part instead of described as a 256k part, where the confusion possibly comes from the manual saying there is 128KB of cache (made up of four 32KB parts).

If you have been looking for 32k x 8 SRAM parts that are described as the usual 256k parts they shouldn't be hard to find. One example is the Cypress CY7C199CN 15ns 32K x 8 SRAM part which might work for you.
http://www.cypress.com/?docID=48466

You can currently buy CY7C199CN-15PXC parts brand new from Mouser for $2 each, or $1.82 each if you buy 10.
 
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