But do you have a matched set to fully populate a board or are you buying them one at a time as you find them regardless of who made them?

I have several dozen of each, all matched and from the same batch. Tested and work in my Cyrix 5x86-133 (2x66) system. I will be populating my fleet of 486 boards with them along with their respective flashable BIOS chips.

Never knew 10ns SRAM chips existed like that! 😳
I only knew of 12ns

But I reckon these chips aren't cheap, right?

Tetrium wrote:

Never knew 10ns SRAM chips existed like that! 😳
I only knew of 12ns

But I reckon these chips aren't cheap, right?

Me neither. I thought there were 12ns chips, though.

I'd like to get my hands on some of that.

Anonymous Coward wrote:

I'd like to get my hands on some of that.

I offered to extend my order quantities to vogons members on page 3 of this thread,
Hypothetical 5x86
but there seemed to be little interest. Two other vogons members will end up with some 10 ns cache.

Tetrium wrote:

But I reckon these chips aren't cheap, right?

$1.77 each, but I also found them for $0.80 each. I trusted the $1.77 source more and they accepted paypal, so that is what I went with.

Damn. I don't know how I missed that.

Anonymous Coward wrote:

Damn. I don't know how I missed that.

Same 🤣

I spoke with Winbond today. This SRAM was discontinued around 2003.

W24257AK-10 is in their system, implying the part was made.
W24512AK-10 is not in their system, whereby W24512AK-12 was the fastest in their system. My W24512AK spec sheet from the 90's only went as low as 15 ns, so there must be a newer spec sheet floating around out there somewhere.

They could not tell me if they ever produced these with yellow lettering, nor do they have the specification sheets. Not a lot can be concluded from this. What I've noticed a lot with just about all high tech companies is that once a part is discontinued, they pretty much abandon and shred all previous knowledge of it.

ISSI claims that these chips were only ever produced as fast as 12 ns and with white lettering. I've been using the IS61C1024-10N chips in my everyday use 486 box and have not had any problems. I'm using the fastest cache settings of 2-1-1-1 at 33 MHz. My uptime is 5 days, 17 hours so far. 3-2-2-2 at 66 MHz also works fine, so even if the cache is a Chinese reprint, it is good enough for the fastest possible 486 system.

Another thought is that the California-based divisions of ISSI and Winbond did not produce, or are not aware of, the 10 ns cache, and perhaps only the Asian divisions of the companies made them for some niche market. I only spoke with the California divisions of these companies. When I inquired about the last production date of the ISSI 15ns chips, I was told 1999, but I have some 1024 ISSI chips with 2002 date codes and the white lettering. Evidence of this was sent to ISSI but I have not received any comment.

EDIT:
Of the 100 '1024' pieces tested, there have been 9 faulty modules.

Of the 22 '257' pieces tested, there has been 1 faulty module.

Of the 36 '512' pieces tested, there have been 0 faulty modules.

EDIT:
Given the 9% failure rate of the '1024' chips, I have a new theory as to their origin. It may be that they were produced by a company other than Winbond or ISSI, perhaps by some discount fab, who figured that putting a brand name of the chip would render them more attractive from a sales perspective.

EDIT:
257, 512, & 1024 chips passed MemTest 4.

The authenticity of this cache is still unknown. Does anyone know how to reliably test DIP cache for 10 ns operation?

no wonder I think that there was no comment from California division... They can't possibly track any Asian activity 😀
Also they will not probably say bluntly that "such items you are having might be fake", so no comment 😀

Should we try to stick with the official claim and look for the 12ns chips?
These might have less chance of being faulty...

But probably they are less readily available either.

The 10 ns '257' chip works fine in a socket 7 i430TX at 83 MHz (FSB) and has passed several weeks worth of rigorus benchmarking on 2 dozen+ CPUs. 64 MB of PC100 RAM was also used in these tests. I've also been running my 486 24/7 with the '1024' chips for almost 3 months without any issues.

From the US-English spec. sheets, the '257' pieces did officially come in 10 ns and the '1024' pieces are listed as low as 12 ns (as of May 1999). Perhaps some spec. sheets in Chinese with a slightly newer publication date will have ISSI '1024' pieces with a 10 ns listing?

I would not be surprised if the Western market didn't bother to sell a faster 10 ns chip as this form factor was already rather obsolete by the 1999 publication date. There may have still been some obscure China-only motherboards using DIP cache after 1999.

Another possibility is that a discount company (other than Winbond and ISSI) made these faster 10 ns chips but figured the chips would sell better if marked with a Winbond/ISSI brand name.

I find that the 10 ns '1024' chips have no issues with a 66 MHz FSB and 3-2-2-2 L2 timing. The 9 out of 100 bad pieces were total failures and I have not had any issues with the remaining 91 chips. A possible reason for the 9% failure rate may be because these chips were never qualified after production simply because the demand was not there (there wasn't a buyer, or perhaps some company bailed on an order). The manufacturing company probably didn't want to spend money to qualify them if they were going to get scrapped, or in this case, sit in a wearhouse indefinately. If that is the case, then there would have been a 91% fab yield, which sounds pretty good to me.

If you are looking for 1024 KB of L2 cache, the easiest combination, by far, is to get 12 ns '257' chips and 15 ns '1024' chips.

Dang, missed out on that too. If you ever feel like doing another I'm definitely "in" on it. 😀 I've got some 10ns 32kx8 laying around, never been able to find anything more dense than that.

Any more of this super sweet cache become available?

It's not really needed. 15ns is fast enough.

kixs wrote:

It's not really needed. 15ns is fast enough.

Where can I find 512k to 1024k of 15ns?

I'm also after both the fast 10n cache (double banked 512kb total) and the 64mb one-stick fpm 60ns ram, please let me know if anyone has any. Its for the Biostar mainboard with a 180mhz amd x5 on it 😀

But the 10ns stuff is fake. 12ns is available for 32kx8, but the 128kx8 stuff is pretty much unobtanium.

Anonymous Coward wrote on 2021-05-21, 23:28:

But the 10ns stuff is fake. 12ns is available for 32kx8, but the 128kx8 stuff is pretty much unobtanium.

Although it does appear to be functional, minus ~10%.

I agree, it's not a bad deal if all you need is 15ns cache and you can weed out the bad ones.