16Kx8 chips were introduced quite late. 32Kx8 chips are considerably more common. Most 386 boards that use a single 8-bit TAG RAM are designed to take a 32Kx8 TAG RAM, and will just use half of the RAM. So any 32Kx8 chip most likely works fine in that board, too. Those common chips usuallly have numbers like 24256 or 62256.

For a 386 or 486 ISA/VLB board 20nS tag is just fine for 33Mhz FSB, from my experience a 15 nS would be better for a 40Mhz FSB if you have options to tweak the cache/memory timings...just an opinion ;p
What speed are you current main cache chips ?

Horun wrote on 2022-09-29, 02:12:

For a 386 or 486 ISA/VLB board 20nS tag is just fine for 33Mhz FSB, from my experience a 15 nS would be better for a 40Mhz FSB if you have options to tweak the cache/memory timings...just an opinion ;p
What speed are you current main cache chips ?

Chips are UM61256FK-15 (15 ns, I guess?). CPU is Am386DX-40.

mkarcher wrote on 2022-09-28, 21:49:

16Kx8 chips were introduced quite late. 32Kx8 chips are considerably more common. Most 386 boards that use a single 8-bit TAG RAM are designed to take a 32Kx8 TAG RAM, and will just use half of the RAM. So any 32Kx8 chip most likely works fine in that board, too. Those common chips usuallly have numbers like 24256 or 62256.

I see. Unfortunately, didn't find something looking as 24 or 62, but found this one: https://www.digikey.com/en/products/detail/re … 9IaAkVIEALw_wcB - 71256SA CMOS Static RAM 256K (32K x 8-Bit).

Or G-LINK GLT725608-15T?

Are they suitable for TAG RAM?

Get 32K x 8 bit 15ns SRAM chips from ebay. Not from chinese sellers.

Cheers,

GoldenPentium wrote on 2022-10-01, 23:19:

I see. Unfortunately, didn't find something looking as 24 or 62, but found this one: https://www.digikey.com/en/products/detail/re … 9IaAkVIEALw_wcB - 71256SA CMOS Static RAM 256K (32K x 8-Bit).

Near miss. 25ns is likely too slow to be used as tag RAM.

GoldenPentium wrote on 2022-10-01, 23:19:

Or G-LINK GLTGLT725608-15T?

Near miss again. This time the electrical paramaters are fine, but the DIP variant is 600 mil (0.6 inch) wide, which is as wide as a BIOS chip or keyboard controller. Cache sockets require 300 mil wide chips (like standard logic chips). Sometimes the 300 mil variation is called "skinny DIP".

I get a lot of hits on ebay searching for w24257ak, which are fine if the speed grade is -12 or -15. I didn't check whether -10 ever existed or whether the -10 chips have fake markings. You might want to check the datasheet for that. The speed grade suffix is just the access time in ns, so 15 or lower should be good enough.

mkarcher wrote on 2022-10-02, 07:07:

GoldenPentium wrote on 2022-10-01, 23:19:

Or G-LINK GLT725608-15T?

Near miss again. This time the electrical paramaters are fine, but the DIP variant is 600 mil (0.6 inch) wide, which is as wide as a BIOS chip or keyboard controller. Cache sockets require 300 mil wide chips (like standard logic chips). Sometimes the 300 mil variation is called "skinny DIP".

I think it is 0.3 though:

GoldenPentium wrote on 2022-10-02, 13:28:

mkarcher wrote on 2022-10-02, 07:07:

GoldenPentium wrote on 2022-10-01, 23:19:

Or G-LINK GLT725608-15T?

Near miss again. This time the electrical paramaters are fine, but the DIP variant is 600 mil (0.6 inch) wide, which is as wide as a BIOS chip or keyboard controller. Cache sockets require 300 mil wide chips (like standard logic chips). Sometimes the 300 mil variation is called "skinny DIP".

I think it is 0.3 though:
Screenshot_20221002-092603_eBay.jpg

Yes, this chip definitely has the correct form factor. I checked for datasheets again: There are a lot of versions of the GLT725608 datasheet floating around in the internet, some of them mentioning only the wide DIP version, some mentioning both DIP variants and some not mentioning DIP at all. You should be fine with that chip.