I don't know your board specifically, but I do know how the cache on 486 boards is implemented in usual chipsets.

It seems your board supports a single bank of cache. This bank consists of four data chips (where your red circle is). You also need at least one tag RAM chip in the DIP28 socket next to the CPU, and likely another tag chip for the "dirty bit" in the DIP22 socket next to it. The most common cache size for 486 boards is 256KB of cache. For that amount of cache, the data chips need to be 64K x 8 fast CMOS SRAM chips (access time 15ns or faster (lower number)). The big tag chip is usually a 32K x 8 fast CMOS SRAM chip. Theoretically, a 16K x 8 chip could do, too, but those were uncommon when your board was designed - and there are two incompatible versions of them, so go for the more common 32K x 8 chip. The small tag chip could be a "x1" or a "x4" chip. For 512KB of cache, a 32K x 1 or a 32K x 4 chip could be used, but those chips don't exist, so the board could be designed to accept 64K x 4 or 64K x 1 chips. 64K x 4 chips don't fit into a DIP22 socket, so I am very confident the board requires a 64K x 1 chip for 512KB of cache. I don't see any jumpers for the cache size near the socket, so I am also confident that the board only supports a single kind of dirty tag chip, which will be a 64K x 1 chip.

So for 256KB of cache, you need to source:

• 4 DIP32 chips of 64K x 8, 15ns or better, e.g. UM61512, W24M512A or CY7C1512
• 1 DIP28 chip of 32K x 8, 15ns or better, e.g. UM61256, W24M256A or CY7C199
• 1 DIP22 chip of 64K x 1, 15ns or better, e.g. CY7C187

All those chips need to support 5V operating voltage. Don't get "low voltage" chips for 3.3V. If you want the maximum possible amout of 512KB of cache, the 64K x 8 chips need to be substituted by 128K x 8 chips, e.g. IS61C1024. The tag chips are big enough to support 512KB without needing to be substituted. Beware that there are a lot of cheap offers for this ISSI chip type on AliExpress that seem to be untested surplus with a dead-on-arrival rate of around 10%, as experienced by the retro community, so if you order them cheap, order 5 or 6 chips if you need four working ones.

This is what I had purchased before I knew of this information:
https://www.aliexpress.us/item/32568048194393 … randl_shipto=US

I am new when it comes to L2 cache

Do I need to buy all three sections of these?

4 DIP32 chips of 64K x 8, 15ns or better, e.g. UM61512, W24M512A or CY7C1512
1 DIP28 chip of 32K x 8, 15ns or better, e.g. UM61256, W24M256A or CY7C199
1 DIP22 chip of 64K x 1, 15ns or better, e.g. CY7C187

I already am looking at buying four dip 32 chips of 65k x 8

AvocadoLongfall wrote on 2022-12-01, 20:16:

This is what I had purchased before I knew of this information: https://www.aliexpress.us/item/32568048194393 … randl_shipto=US […]
Show full quote

This is what I had purchased before I knew of this information:
https://www.aliexpress.us/item/32568048194393 … randl_shipto=US

I am new when it comes to L2 cache

Do I need to buy all three sections of these?

4 DIP32 chips of 64K x 8, 15ns or better, e.g. UM61512, W24M512A or CY7C1512
1 DIP28 chip of 32K x 8, 15ns or better, e.g. UM61256, W24M256A or CY7C199
1 DIP22 chip of 64K x 1, 15ns or better, e.g. CY7C187

I already am looking at buying four dip 32 chips of 65k x 8

You bought 10 DIP28 chips of 32K x 8. You can use one of these chips as tag ram. You can also use them as data RAM, but you will only get 128KB of cache then. Still much better than no L2 cache. Possibly you can skip the DIP22 chip, but this will severely hurt performance in write-back (WB) mode if it works at all. If you configure the board to use the cache in write-through (WT) mode (might be a CMOS option, if you don't find one, it's impossible), the DIP22 chip is not needed.

I also plan on installing in the future soon an intel DX4 or someday an intel Pentium Overdrive cpu after installing the cache that has been shipped out to me. Some have told me the computer that I was playing Duke Nukem 3D on was pretty impressive for the screen size and detail setting for a mid sized screen. So after the cache is installed, it will be even faster and go well with windows 95A. Along with a DX4, it will undoubtedly rock the desktop. 😁

mkarcher wrote on 2022-12-01, 23:44:

You bought 10 DIP28 chips of 32K x 8. You can use one of these chips as tag ram. You can also use them as data RAM, but you will only get 128KB of cache then. Still much better than no L2 cache. Possibly you can skip the DIP22 chip, but this will severely hurt performance in write-back (WB) mode if it works at all. If you configure the board to use the cache in write-through (WT) mode (might be a CMOS option, if you don't find one, it's impossible), the DIP22 chip is not needed.

Looks like the OP didn't install the dirty chip and is having trouble: Having some issue getting the L2 cache to work

Would it be ok to temporarily put a pull up resistor between pins 9 and 22 of the dirty ram socket to simulate "always dirty"? (I'm a software person OP, don't try this without mkarcher's OK)

jakethompson1 wrote on 2023-02-26, 05:03:

Would it be ok to temporarily put a pull up resistor between pins 9 and 22 of the dirty ram socket to simulate "always dirty"? (I'm a software person OP, don't try this without mkarcher's OK)

Yes, a pull-up or pull-down resistor (use around 10k) will put the cache into "always dirty" mode. It depends on the chipset whether "dirty" is represented by high or low. The other variant would be "always clean" (even if it actually is dirty) which is a recipe for disaster. So a 4.7K or 10K resistor between either 9 and 11 or 9 and 22 should make the board stable, but less performant than with the dirty RAM installed.