Rev 1.3 might just be the revision of the PCB, but not the COAST version I´m afraid.

Besides the COAST version there are other incompatibilities due to proprietary formats of COAST sticks for certain mainboard manufacturers.

Is there any jumper work to be done when expanding L2 cache here?

Statson mentions a jumper but it is not on the motherboard. The boards manual does not mention any jumper regarding cache sizes.

That is an odd Coast, with four 32K x 18bit chips plus TAG. All of my 256k COAST for Pentium boards (Asus, FIC and a HP) have two 32K x 32bit chips plus TAG.
My guess is that being 18bit wide they are for a specific motherboard and is not compatible with the majority of Pentium boards

Thanks alot. Than I'm out of luck with this module and try to get another one.

Hi there. I have the similar issues and don't want to create another topic for that.

I have ASUS P/I-55TP4XE motherboard (rev 2.1).
Here is the manual: https://pcrebuilding.altervista.org/9/downloa … pi_p55tp4xe.pdf

It has 256K of cache already in chips but I wanted to be cool and bought a COAST module with UM61L3232AF-7 chips on it. Here is chip datasheet: https://www.datasheetarchive.com/pdf/download … m=UM61L3232AF-7

I removed all cache ICs and put the cache into the slot. The system either boots with 0KB of cache with COAST installed or boots and POSTS 41 that means VRAM error. It beeps in the same way: one long and high beep and two short and low (haven't heard that yet).

The manual doesn't say something about COAST compatibility and I don't know what COAST version it is 🙁

ver 2.4 of my mobo has a special jumper that I should set if I use cache stick. Not a my case. I have only two options: cache voltage (not sure it affects cache module) and cache size (set to 256K). What else can I test?

The ASUS P/I-55TP4XE is known to not be picky at all about COAST sticks. I used it to test all kinds of sticks for years.
Did you put jumper JP16 in position 2-3?
A picture of the backside of the module might be useful.

@majestyk thank you for your answer. There is no JP16 on my board, it appeared on rev. 2.4 and mine is 2.1

I've just noticed two strange looking pins on the second chip. According to datasheet these are pins 70 and 65 (VCC0 and VCC) but I don't seem any connection on the first chip to these pins as - no traces on both sides, actually only few of them are used. Seems like chips are powered somewhere else, there are lots of VCC pins.

The COAST I have is the most modern one as I understand - pipeline bursted cache so probably it's not supported by my revision of the motherboard (or by all revisions).

This is the situatiom on Rev. 2.4 and 2.5:

Jumpers 16 and 12 are present.
On your Rev. 2.1 there´s one Jumper at this position, is it 12 or 16?

Pipeline Burst modules should be perfect on all revisions of this Intel 430FX chipset board. You just cannot combine a pipeline burst COAST module with onboard async. SRAM.

Those "blackish" pins and soldering pads do look a bit corroded...or burnt.

There is only jumper 12, no sign of JP16 (like they reserved space for it but did not add on 2.1).

Agree, they look even more like burnt, not corroded. Maybe even burnt inside, because they are not connected outside. This one cost me just $2 with $2 delivery, so I'm going to buy a new one.

Do you know something about this one from Samsung?

https://i.ebayimg.com/images/g/QcIAAOSwkmFhnhTj/s-l1600.jpg

Yay.

I found another model something like month ago. Tried it without luck. And only after reading the chip description I saw it's a DRAM module. That standard is VERY strange indeed. So many variations and not so many information. Surely it did not work too but did not burn my motherboard.

And then I ordered one of the 256K modules on eBay, AND IT WORKED.

I need to fix the RTC chip (will try one from Necroware, I ordred components already) and will test how this Coast module differs in speed with standard SRAM - was it worth it.

Congrats!
256K pipeline-burst SRAM should make a significant performance improvement over onboard async. SRAM chips.

The COAST "standard" and all of it´s variants can give you hell. Everybody was doing their own proprietary thing to make sure customers bought their (overpriced) modules.

Is there a need for new coast sticks?

I know someone made one that fits those oddball 486 mobos that like to blow up with the more common coast sticks.

Can we identify the differences between various types of coast configurations and make one that was programmable for different motherboards?

Maybe we could make one that allowed use of modern/easily available sram chips?

I’d be willing to do the pcb if someone was willing to help with the design. 😀

One with press in curled pin sockets would be cool kinda like the old trident pci video card expandable ram sockets.

majestyk wrote on 2022-09-16, 17:13:

Congrats!
256K pipeline-burst SRAM should make a significant performance improvement over onboard async. SRAM chips.

The COAST "standard" and all of it´s variants can give you hell. Everybody was doing their own proprietary thing to make sure customers bought their (overpriced) modules.

Thank you. That would be such a pity if it's slower 😀 So some performance boost will be a little compensation for my efforts 😀

Sphere478 wrote on 2022-09-16, 17:58:

Is there a need for new coast sticks?

I don’t know tbh. I just wanted to put to my builds everything rare and unusual, that’s why I bought CNR network card and AMR modem. I’ve never seen COAST modules before and didn’t even know about them - they were used only in small subset of Pentium PCs as I understand. I just happened to buy a case with Pentium mono in it and it had that unusual connector (actually 2 - there is combined ASUS PCI/ISA slot as also).

So unlike 4MB 30 pin SIMMS for example that can be of use on most of 486 and even 386 builds these modules won’t be very popular. I doubt there can be ‘universal COAST’ known to work everywhere and without that, and also strange cryptic documentation that turns into game ‘find something that fits you’.

512K module will not give much performance over 256K as I read so I won’t bother in searching for 512K model. I have working one at last and that’s enough.

My understanding is 512k is required on boards that you want to put lots of ram into (also more tag ram is needed) in order to avoid slower cached ram memory ranges. Which usually ends up where windows wants to use memory.

So for anybody searching for the Coast module.

ASUS P/I-55TP4XE motherboard (rev 2.1)
Coast module is Elpina HT-VX ver 3.1 (don't know if it Coast version or board revision).
Memory chips are CMEI 61M3232AT-6

I don't know the type of SRAM - there is no datasheet for that chip.

Sphere478 wrote on 2022-09-16, 18:48:

My understanding is 512k is required on boards that you want to put lots of ram into (also more tag ram is needed) in order to avoid slower cached ram memory ranges. Which usually ends up where windows wants to use memory.

Probably. I've just read an old post of a man searching for 512K for his board with 256MB of RAM. I have 64 and that's more than enough for my P166 W95 build - I managed to live with 8 back then on 486 dreaming for 16MB. So 32-64 for Pentium build is something beyond my dreams of year 1998 😀

I've just recently had my first ever experience with cache modules. I recently purchased an AT case that had a PCChips M520 in it. They joke about "Troll builds" here, but this thing was one in real life, and I feel sorry for the person who had to use it. It had a K5 PR133 (100 MHz) chip, 128 megabytes of EDO, an empty cache slot, and fake cache on the board (so no L2 at all). Even by the standards of the time, this thing was slow.

I have a PCChips M507 that I'm not using (it's nearly identical to the M520 except it has the FX chipset FX instead of VX). It has a cache module installed, so I borrowed it thinking it would work for sure in such a similar motherboard, but it in fact did not, so I still had no L2 cache. I had to buy one on Ebay that was a pull from a Compaq and it did work. But it's touchy - I had the FSB set to 75 Mhz to get 188 MHz from the 233 P55 I stuck in it (single voltage motherboard so it's overvolted) and with no L2 this had been perfectly stable; add the cache stick, and it nuked Windows so badly that I had to reinstall. But at 66 MHz FSB it has been perfectly stable, and a major improvement in the system's speed.

In the future I'd like to upgrade the board with a K6-3 450 with an add on VRM. Does Necroware have a store?

The top one works with the M507, the bottom one works with the M520 I might try it in the M507 at some point to see if it also works in that board.

Repo Man11 wrote on 2022-09-16, 19:23:

In the future I'd like to upgrade the board with a K6-3 450 with an add on VRM. Does Necroware have a store?

He was planning to, but not yet, so I ordered boards (he opensourced gerber files) and components, will try to solder it when everything comes.