Hi! If you can, dump the bios and with a program to bios mod look for the hidden settings, change them and burn bios back

Thank you for the help 😀.

First i did try setting the board to 50 mhz and see if the cache is available. Unfortunately this did not work 🙁. Still no Cache.

Also my PhoenixBios looks diffrent and i have no cache settings at all. I can not set any L1 Cache setting.

Yes i did think about Dumping the Bios as well, but which Software is able to read the PhoenixBios 4.04 from Compaq ? Do you gave a suggestion for me how to read and edit it proberly?

Is it possible that compaq just added Dummy cache slots there with no function ? But when i turn on the Computer i can feel the chips getting warm. I also did installed one chip wrong the first time and it went very Hot. So power is there.

This motherboard drives me crazy 😀...

It is possible. There were quite a few boards with fake cache around that time

The chip that was inserted the wrong way is probably dead now and needs to be replaced.

Is there any Download source for the Compaq BIOS? MAybe it can be found on some "System Recovery" CD from Compaq.
It´s possible the "Memody Cache" option has been hidden and dissabled, a tool like Modbin for Award BIOS does not exist for Phoenix (afaik) but "CBROM.exe" can do a lot of modifications.
It´s running under DOS and maybe there´s some Hex-editing to do.

It´s also possible that the Memory Cache option is only hidden as long as BIOS isn´t happy with the Cache configuration (cache size, TAG-size...) and shows up as soon as enverything´s o.k. (I´m still not sure if 256K is o.k. for TAG or if 128K or 64K would be necessary).
or it´s possible
that there´s some hardware mod needed to enable cache like adding missing components. There are a lot of "vacancies" in the area between the TAG socket and the UMC chip for example.

majestyk wrote on 2022-09-21, 05:53:

You can try setting the frontside bus to 50 MHz temporarily, to "make it easier" for the slower 20nS SRAMS. […]
Show full quote

You can try setting the frontside bus to 50 MHz temporarily, to "make it easier" for the slower 20nS SRAMS.

Otherwise there might ba a BIOS switch to enable/disable L2 cache that´s hidden and set to "disable" as default. Is there a switch for enabling/disabling L1 cache present?

In Phoenix BIOS 4 rev 6 you would have to expand the menue entry "Memory Cache" (if visible).

phoenix4_6.JPG

Finally friday 😀 and i have more time to test things 😁!

I did test:

• 50MHz
• 60MHz
• 66MHz

and also did replace the cache chips all with new once.

Also I checked once again all my BIOS Settings in none of the Menus Cache is even mentioned. 🙁

All things again with no luck for me 😁... What shall i do? I can not believe that i can not getting it to work.

majestyk wrote on 2022-09-22, 05:29:

The chip that was inserted the wrong way is probably dead now and needs to be replaced. […]
Show full quote

The chip that was inserted the wrong way is probably dead now and needs to be replaced.

Is there any Download source for the Compaq BIOS? MAybe it can be found on some "System Recovery" CD from Compaq.
It´s possible the "Memody Cache" option has been hidden and dissabled, a tool like Modbin for Award BIOS does not exist for Phoenix (afaik) but "CBROM.exe" can do a lot of modifications.
It´s running under DOS and maybe there´s some Hex-editing to do.

It´s also possible that the Memory Cache option is only hidden as long as BIOS isn´t happy with the Cache configuration (cache size, TAG-size...) and shows up as soon as enverything´s o.k. (I´m still not sure if 256K is o.k. for TAG or if 128K or 64K would be necessary).
or it´s possible
that there´s some hardware mod needed to enable cache like adding missing components. There are a lot of "vacancies" in the area between the TAG socket and the UMC chip for example.

I have a "Recovery CD" downloaded from archive.org. I will have a look if i can find it 😀
In the Manual it states that 32k x8 is the TAG size.

I will also try to download the BIOS in DOS and Modify it with CBROM ? I am totally lost 😖...

Take high res pic of mobo front and back.

There may not be any traces to your cache sockets.

Dump your bios and upload it.

Perhaps someone here can mod it.

Also, do I recall that you inserted one backwards? May have fried mobo.

Sphere478 wrote on 2022-09-23, 17:37:

Take high res pic of mobo front and back. […]
Show full quote

Take high res pic of mobo front and back.

There may not be any traces to your cache sockets.

Dump your bios and upload it.

Perhaps someone here can mod it.

Also, do I recall that you inserted one backwards? May have fried mobo.

Okay, I try my best will disassamble the computer and take good pictures of it.

Do you know which software i can use to dump it?

Yes, but it was very short and replaced that one. I dont think that it is fried 😀 everything works great except cache...

Uniflash 140 or 1.40 I forget what the version is. That’s what I use it’s dos based. You have to boot without high memory programs

Oh my GOD it works FINALLY 😁

I just did try it again and set the FSB to 66MHz (CPU is now running at 100MHz, I have the 120MHz Model - Intel Pentium A80502120 SY062)
Do you think running it in 66 MHz is fine instead of 60 MHz FSB ?

120MHz Mode is not working (Connecting bin 1-2 and 3-4). This Version was undocumented anyways.

I have now about the performance when i have it running at 120MHz but with 100 MHz. Maybe a bit less. Oh dear 😁. I gained nothing.

Photo of the installed cache chip on this motherboard please.

Cheers,

Hi @Pentiumspeed,

i used these ones.

Exact Type I installed

Winbond 32Kx8-Bit 256K 15nS High Speed Static RAM CMOS IC DIP-28 THT W24257AK-15

Cheers 😀

Sweet!

So it only works on 66mhz setting? Weird…

Run memtest for a few Hours to confirm stability.

You could also try the settings mentioned in the k6 mod thread in my sig. (end of guide on page 13) Re: SUCCESSFUL K6-2+ to K6-3+ Full Cache Enable Mod

I bet this is one of the customized BIOSes that only start the machine when everything is configured according to the manufacturers standards / limitations.
As you can see Cache options are hidden so the user is prohibited from making any changes. But cache is enabled when certain (allowed by Compaq) conditions are met.

1. If your new cache chips are detected and running at 66 MHz FSB they are o.k.. Leave them as they are. The highest possible FSB should be your goal anyway.
2. Leave FSB at 66Mhz and try a Pentium 133. Set multiplyer x2 manually using the jumpers.

3. The cache performance of 123% compared to regular system memory is a bit disappointing, but this is probably a chipset (or BIOS) limitation.

long shot, kinda doubt it, but I Wonder if it has write thru policy set? might be able to force write back with the asus p5a simple mod?

Re: Pentium 200, non-mmx - low dos benchmarks?