I've been looking for an Octek Hippo myself for a while. I'd try ebay Germany if I were you. That is the only place I have ever seen them for sale.

There's some info on this somewhere on Red Hill Guide - from memory they were a bit dubious of it.

I've worked on a few Socket 7 Octek boards back in the day but none of their 486 boards.

I have one of those Hippo DCA2 boards, got it cheap on eBay a couple years ago, but I've never really done anything with it. I haven't been able to find any of the special EDRAM to go with it, and though it'll work with regular FPM, it's just like any other cacheless 486 then. It's also finicky as hell... it doesn't get along well with a lot of VLB cards.

My mate got a Octek 488 DX4 100 in 95 from a local store and I remember it being quite unstable. The m/b was Octek but not sure if it was a hippo or not.
I ended up working in the same store 5 years later and never thought much of Octek hardware in general, but it may have to do with hardware combinations as Octek just supplied parts the store built the PC's to order.

Even some of the stuff Red Hill list as good hardware they openly admit only worked with a certan video card, sound card, etc

This is the mobo that I had been using throughout the 486 era. IIRC, the "Dynamic Cache Architecture" were implemented in different levels. The full implementation was significantly expensive due to the need of a proprietary type of EDRAM memory. Motherboards with this full design were labeled "DCA2" and were reasonably fast but pricy and rare. In fact, what was well-sold in the market was a budget version without the ability to take the advantage of EDRAM memory but merely with the extra-wide memory bus. It was labeled "DCA1" or simply "DCA". IMO, these "perfect" labels were subtle enough to make Octek the winner in many benchmarks by testing its cutting-edge DCA2 unit and then leveraged Octek's market share by mass selling the compromised DCA/DCA1 units. For an ordinary user, he/she might not necessarily be aware of the substantial difference among DCA2 and DCA1/DCA.

Despite, I had a pretty positive impression on the DCA2 mobo. In my ad-hoc stress test across different 486DX mobos, the DCA2's overall performance was outstanding in dealing with those heavy-duty CAD and 3DS tasks. But I didn't do any gaming test or compatibility test. In the other hand, the DCA1's performance was below the most of 256k cache-ed 486DX mobos and was equivalent to those cache-less 486DX mobos. Attached are pictures of my DCA2 mobo and its EDRAM. It is currently in my parent's apartment which is located on the other side of the earth from my home 😀. I might have access to it after a few months and I'm expecting do some benchmark PK aginst my other socket 3 mobos including PVI-SP3 and FIC-PIO3.

This is my 1st post in this forum and my apologize for my poor English.

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Interesting and rare hardware - thanks for posting.

I'd like to see some Speedsys test results from that board.

Great post thanks for the info.

Your English is better than some native English speakers I know!

Thanks.

The DCA2 mobo has two EDRAM slots but typically shipped with only one EDRAM module installed. I'm deeply tempted to fill up the rest empty slot, but I've been looking for the 2nd EDRAM module for years without luck. I'm wondering how many units were actually sold in its history.

I looked up the product number on those DRAM chips. I've attached the PDF.

A fancy, all-in-one SRAM + DRAM package. Before CPU companies started integrating L2 cache, this must have been seen as a possible direction for improving performance.

The 4Mb Enhanced DRAM (EDRAM) combines raw speed with innovative architecture to offer the optimum cost-performance solution fo […]
Show full quote

The 4Mb Enhanced DRAM (EDRAM) combines raw speed with innovative architecture
to offer the optimum cost-performance solution for high performance local or
system main memory. In most high speed applications, no-wait-state performance
can be achieved without secondary SRAM cache and without interleaving main
memory banks at system clock speeds through 50MHz. Two-way interleave will
allow nowait- state operation at clock speeds greater than 100MHz without the
need of secondary SRAM cache.

The EDRAM outperforms conventional SRAM cache plus DRAM memory systems by
minimizing processor wait states for all possible bus events, not just cache
hits. The combination of data and address latching, 2K of fast on-chip SRAM
cache, and simplified on-chip cache control allows system level flexibility,
performance, and overall memory cost reduction not available with any other
high density memory component. Architectural similarity with JEDEC DRAMs
allows a single memory controller design to support either slow JEDEC DRAMs or
high speed EDRAMs. A system designed in this manner can provide a simple
upgrade path to higher system performance.

Apparently, this in-memory cache scheme was an early attempt of integrated L2 cache, which was eventually defeated by the in-CPU L2 cache scheme since PPro.

I'm deeply tempted to fill up the rest empty slot, but I've been looking for the 2nd EDRAM module for years without luck.

I mentioned previously that I hadn't been able to find any EDRAM SIMMs... but that's not entirely true. It's more that I haven't been able to find any for a price I've been willing to pay, and frankly, that board isn't a high-priority project, so my price threshold is pretty low.

Here's the thing: those modules actually are available on eBay fairly frequently, but there's a bit of a catch. It's a little-known fact that some versions of the DEC KZPAC RAID controllers used 8MB EDRAM SIMMs as cache modules. Those RAID controllers are fairly common, the ones with EDRAM somewhat less so but can still be found if you look for 'em (most came with regular FPM, and it's usually not mentioned in the descriptions, so you have to either look closely at the pictures, or ask the seller to tell you what the chip markings say).

The problem is, of course, that you have to buy the RAID controller to get the SIMM, and between the purchase price and the shipping for a full-length card, it ends up being pretty expensive for 8MB of RAM. Though if you wanted to play with a SCSI RAID controller anyway, the investment might not be such a problem... you can pop a regular 60ns SIMM back into the thing and use it that way.

This allows me to understand that my frustration in finding this stuff maybe due to my inappropriate search scope, which was too narrow just focusing on mobo accessaries. A new search for RAID controller returned much richer info and therefore opened new hope of finding possible substitutes. The only question is whether the EDRAMs used on these DEC KZPAC RAID controllers are compatible with DCA2 mobo, or its specification is closer enough to the RAMTRON SIMM used by the DCA2 mobo? An easy way to getting this kind of answer is always begin with a visual inspection. Unfortunately, the pictures that I can find on the Web are either too small or too blur. I think that I need to revisit the computer surplus store in my area and try my luck again. I still remember that I've seen some boards in similar shape but I just paid no attention on all of them in the former time. If yes, I may have better chance to know its specification from the real hardware, or I can buy it right away since they usually ask for a pretty reasonable price.

Anyways, this reveals that the major profit of EDRAM were actually from the peripheral applications. And the DCA2 was an attempt to take advantage of this technology on motherboard. Once I have access to my old DCA2 system in my parents home afer months, I will test it with tools such as Speedsys and report back. Thanks!

I finally managed to get my hands on a functional DCA2 board. Years ago I already found one (with two 8 MB DynamiCache modules) but it was heavily corroded and not revivable.

Now, it unfortunataly turned out that one of the memory modules was not recognized by the motherboard. I supposed at least one memory IC being defective. As pointed out by "dca2" one source of EDRAM chips are these DEC KZPAC resp. Mylex DAC960 RAID controllers. I sourced one of them equipped with a 4 MB EDRAM SIMM cheap on ebay. These SIMMS are also working with the DCA2 motherboard.

A lot of soldering work was necessary to figure out, which and how many memory chips on the Octek 8 MB SIMM were non-functional:

One fried memory IC was identified and replaced and all was again soldered together.

Speed tests and benchmarks will follow...

After long time I made some tests with the DCA2 hardware. Configuration isn't easy, because the documentation is pretty poor.
No way to switch the Am5x86 chip and other WB enhanced chips to writeback mode.
Speedsys says 5x86WB cpu, suggesting activated wb mode, but L1 throughput shows that it isn't.
Even with the corresponding pins directly bridged on the CPU, the system will not start.
Pentium Overdrive chip seems to work excellent with L1 WB activated. Cx5x86 does not work at all, the system locks up immediately.

BastlerMike wrote on 2020-03-02, 21:16:

After long time I made some tests with the DCA2 hardware. Configuration isn't easy, because the documentation is pretty poor. No […]
Show full quote

After long time I made some tests with the DCA2 hardware. Configuration isn't easy, because the documentation is pretty poor.
No way to switch the Am5x86 chip and other WB enhanced chips to writeback mode.
Speedsys says 5x86WB cpu, suggesting activated wb mode, but L1 throughput shows that it isn't.
Even with the corresponding pins directly bridged on the CPU, the system will not start.
Pentium Overdrive chip seems to work excellent with L1 WB activated. Cx5x86 does not work at all, the system locks up immediately.

Amazing! I'm still hunting DCA2 but no lucky. Could you compare the EDRAM SIMM VS EDO SIMM on DCA2 and get 30% boosting?