citronalco wrote on 2022-05-08, 21:34:There are also -12N and -10N chips sold on Ebay.
Yes, they are all fake, so ignore the printing on the case. Upperside and unde […]
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There are also -12N and -10N chips sold on Ebay.
Yes, they are all fake, so ignore the printing on the case. Upperside and underside. Completely.
Over the last years I've ordered ~100 pieces from different sellers. Not because I'm stupid enough to get fooled multiple times, but because it's damned hard to get L2 cache chips, especially ones with 128kx8.
Usually 3 out of 10 are completely broken (TL866 shows "Bus error" when testing them as 64kx8 chips as 128kx8 are unsupported), and another 2 fail when on the board.
The latter is the most annoying part: I swap them in into a working board one by one, and unzip a huge file. Should run a few minutes. If unzip shows CRC errors the chip is bad.
So you're left with 5 out of 10 working.
I run them stable with 2-1-1-1 at 40 MHz, so they should be at least 15ns parts.
So yes, you can buy them. But half of them are rubbish, and sorting those out can be tedious.
Unrelated to these ISSI chips: Found out that some boards are extremely picky about the TAG chip, regardless of frequency or waitstates: Some work with whatever chip you plug into the socket. For others I had to try several chips from several manufacturers (yes, including non fake chips) until they pass the unzip test. Or even boot.
Hello,
I found procedures to test it:
1) I tested in the Asus SV2GX4: Cache configured to 256kB with 4 times 64kx8 and a tag 32kx8, that configuration is 100% working.
Then I replaced only one of the 64kx8 with one of the 128kx8. For (probably) working chips the board show 512k (of course it will not work correctly, but the Bios detects something a least).
2) Test 2: is measuring power consumption in idle. I don't have a SRAM tester, but at my workplace a colleague measured the power consumption for me. An original Winbond 64kx8 takes ~ 1 mAmp.
OK, so all of the 20 were tested. I guess only 2 had something like one milliAmp, some were in the 10 milliAmp range, some ~30 - 50. And there was one chip which was taken 100 milliAmps, 🤣. So again only 5 Volts and ground were connected to the chip.
So from test 1) there were only 8 chips that passed. 12 chips bad. 1 was special, when this chip was in, the board did not boot at all.
So from the 8 I took a set of 4, put it to the board, jumpered the board correctly to one bank 512kB cache. Result: The board showed 512kB, but could NOT boot from floppy. Hangup. Also not with slowest cache timing in Bios. With L2 cache disabled, the board booted 😁
So about test 2: As far as I remember the one chips with the (by far too high) power consumption is the one where the board does not boot at all.
So test 2 is maybe really a great test, I have to repeat it. Obvioulsy 10milliAmps is already far too much for such a 128kx8 SRAM chip. The datasheet say 10milliAmps maximum idle power consumption. So I have to find the one or 2 chips (out of 20, what the fuck), which have 1milliAmp idle only. The 12 that failed test one, I have put to garbage.
So it seems I was unlucky, far away from 50% working.
The seller refunded the money already.
I ordered one more time 20 chips ISSI61C1024 from another chinese seller, maybe I manage to get 8 working pieces at least. Expecations are low of course.