Awesome, now I see what you meant. Thank you so much! I'll update git with your version.

Today I found out the VL82C483 supports more than 64MB. Two of the three empty cache slot pins could easily be wired to a18-19 to support 1MB of cache, ouch.. this makes me want to make a 1MB module now.

Previously I made the assumption that the bios is shared with the Deskpro series (as the setup utility is), but this is actually not the case. There is actually no bios update available for the prolinea series, I've ordered an adapter and will be dumping the original bios shortly, so I can see if the bios supports the bigger caches, like you proposed earlier, and see if my 1MB cache is an option or I can make it an option.

rasz_pl wrote on 2024-08-29, 06:35:

Edit: btw https://github.com/wichers/Compaq-Cache-Modul … 001_front_2.jpg hmm why did they put resistors after the buffers? and on 1OEs too, weird.

Indeed, I'll have a look at the datasheets to see if something is mentioned about this.

Dumped part of the bios using debug.exe. Bios checks (according to VL82C425 datasheet) for single or double banked cache, but after that it does its Compaq thing and limits cache to 128KB or 256KB. After writing to cache and validation it ends up setting 128KB or 256KB:

1F000:14C0                 mov     al, 19h
2F000:14C2                 out     0ECh, al
3F000:14C4                 in      al, 0EDh
4F000:14C6                 test    al, 10000000b
5F000:14C8                 jnz     short has_dbl_bank
6F000:14CA                 mov     al, 19h
7F000:14CC                 out     0ECh, al
8F000:14CE                 in      al, 0EDh
9F000:14D0                 and     al, 11111000b
10F000:14D2                 or      al, 11b         ; set to 128KB
11F000:14D4                 xchg    ah, al
12F000:14D6                 mov     al, 19h
13F000:14D8                 out     0ECh, al
14F000:14DA                 xchg    ah, al
15F000:14DC                 out     0EDh, al
16F000:14DE                 mov     ebx, 8000h
17F000:14E4                 jmp     short loc_F1500
18F000:14E6 ; ---------------------------------------------------------------------------
19F000:14E6
20F000:14E6 has_dbl_bank:                           ; CODE XREF: F000:14C8↑j
21F000:14E6                 mov     al, 19h
22F000:14E8                 out     0ECh, al
23F000:14EA                 in      al, 0EDh
24F000:14EC                 and     al, 11111000b
25F000:14EE                 or      al, 100b        ; set to 256kb
26F000:14F0                 xchg    ah, al
27F000:14F2                 mov     al, 19h
28F000:14F4                 out     0ECh, al
29F000:14F6                 xchg    ah, al
30F000:14F8                 out     0EDh, al
31F000:14FA                 mov     ebx, 10000h
32F000:1500
33F000:1500 loc_F1500:                              ; CODE XREF: F000:14E4↑j
34F000:1500                 mov     al, 99h
35F000:1502                 out     84h, al

So 1MB of cache is not supported out of the box 😉

Ok, re-designed the entire thing "again" (indeed, that's three times already 😉). There is now an option (by soldering a resistor) to configure 256KB, 512KB or 1MB of cache. If you don't want to modify your bios and add two wires to your motherboard, 256KB it is.. Pricewise there is no difference, and theoretically the Prolinea supports 128MB of RAM. I still need to clean tracks and check VIAs.

rasz_pl wrote on 2024-08-24, 14:24:

4. IS61C3216 doesnt look to be readily available from reputable sources and might end up more trouble than two IS61C256

You already had foreseen the usage of two chips, didn't you 😉

sander wrote on 2024-08-31, 15:11:

Ok, re-designed the entire thing "again" (indeed, that's three times already ;-)). There is now an option (by soldering a resis […]
Show full quote

Ok, re-designed the entire thing "again" (indeed, that's three times already 😉). There is now an option (by soldering a resistor) to configure 256KB, 512KB or 1MB of cache. If you don't want to modify your bios and add two wires to your motherboard, 256KB it is.. Pricewise there is no difference, and theoretically the Prolinea supports 128MB of RAM. I still need to clean tracks and check VIAs.

rasz_pl wrote on 2024-08-24, 14:24:

4. IS61C3216 doesnt look to be readily available from reputable sources and might end up more trouble than two IS61C256

You already had foreseen the usage of two chips, didn't you 😉

The attachment front_render.jpg is no longer available

Hi,

Is there 4 more solder spots for extra 4 chips to make 256K cache card?

Cheers,

sander wrote on 2024-08-29, 10:23:

rasz_pl wrote on 2024-08-29, 06:35:

Edit: btw https://github.com/wichers/Compaq-Cache-Modul … 001_front_2.jpg hmm why did they put resistors after the buffers? and on 1OEs too, weird.

Indeed, I'll have a look at the datasheets to see if something is mentioned about this.

its either pull-downs or something silly like 10 ohm in series, both would clean the signals (ringing, picking up noise from nearby tracks) at the cost of rise times.

pentiumspeed wrote on 2024-08-31, 16:30:

Is there 4 more solder spots for extra 4 chips to make 256K cache card?

yes, on the back

rasz_pl wrote on 2024-08-29, 06:35:

Edit: btw https://github.com/wichers/Compaq-Cache-Modul … 001_front_2.jpg hmm why did they put resistors after the buffers? and on 1OEs too, weird.

Couldn't find anything in the datasheet, maybe there were timing issues between the chipset and the SRAM chips. So they might have introduced an artificial propagation delay. The hack of using resistors would act like a delay line for the memories, thus making the SRAM timing acceptable. Would be nice to know what the resistor values were..

pentiumspeed wrote on 2024-08-31, 16:30:

Is there 4 more solder spots for extra 4 chips to make 256K cache card?

Yes it's double banked (see github pictures) with full 9-bit TAG/DIRTY, if you hack your motherboard you can use 1MB if not you can use the standard 256KB that's supported by the bios by standard. But as it's double banked there are 8 SRAM chips by default.

Another reason for resistors in series is cutting down on signal reflections and reduce current if shorted or over driven.

This is good practice to do.

Cheers,

You people... all of you... I can't thank you enough.
I have been searching for that 128k 1970005-001 for so many years. Last time I saw one for sale(that actually existed) was ebay in January... sold for 15 freaking bucks.
My first real pc was a presario cds 866.. 12mb of ram, 340mb hd, and a 486 sx2 at 66mhz. I still have it, and was lucky to find a presario 833 that was in 85 percent shape, my 860 is probably around a 50% due to age, a garage it was in for a decade and rats.....
I have wanted the cache so badly. And now I have it within my sight... and a 256k one at that!
I've wished I could talk with the designers or people who worked on them in 92 or 93.
I will be figuring out how to order this.. I'm a complete novice when it comes to more than simple soldering. So navigating github will be a challenge, but I need this. My first pc deserves it, especially since its maxed out with a dx4odpr100(meby will find a pentium 83 for it) and all the memory it will recognize. And the Soundblaster 16 it came with is perfect.
I just need this cache for the cherry...
Thank you all again for helping an obsession of mine come close to fulfillment....

> I'm a complete novice when it comes to more than simple soldering

If sander succeeds he will most likely end up with few working prototypes.

rasz_pl wrote on 2024-09-12, 05:46:

he will most likely end up with few working prototypes.

Definitely! I have a couple of PCBs and parts for other projects that are in backorder. It will take a week or three before I have the first PCBs..

Update that increases this cache module interest. I just bought second Compaq Prosignia 4/33 motherboard based on VLSI 483. The other one is based on VLSI 481 is now in my hands.

Second update: Motherboard arrived few days ago, in good condition.

Eagerly waiting for confirmation that cache module works.

Cheers,

This is a great project and I'll look forward to testing this.
I have 2 compaq prolinea systems (4/50 and 4/66). These systems were everywhere in schools and libraries so many survived.
Many of us have these systems in storage, just waiting for this moment. Mine have the Overdrive DX4100ODP in them, so this just is the very last part (Opti 924 for sound and midi).
It brings me joy to see the full potential of a system realized.
Message me if I can help for testing (I've not ordered PCBs though I'm familiar with soldering) and best of luck

sander wrote on 2024-09-12, 18:37:

rasz_pl wrote on 2024-09-12, 05:46:

he will most likely end up with few working prototypes.

Definitely! I have a couple of PCBs and parts for other projects that are in backorder. It will take a week or three before I have the first PCBs..

Just let me know when and I will gladly cover whatever you think is fair price.
I honestly hope you can get it working, just so 256k will work on these fantastic systems. It feels like the future when awesome things like this can be reverse engineerifyied into existence. It's just magic..
I of course will be checking back in every week or so(probably more.. due to my lecherous need for my old PC's to work forever. Lol).

Thank you again to everyone on here.

Also I forgot to say, I have recently been going through the learning for installing and working with the bios on the compaq I have. I also have another motherboard for it. So I can test with both if that helps. And I would pay for shipping both ways, just to make this happen.
I'm not sure if it would need any bios messing, or if it just auto connects. I didnt see much in the bios other than if it has extra cache or not.

I have two of these machines: a Prolinea 4/66 desktop and a Prolinea MT 4/50 mini tower. I've been hunting for cache modules what seems like forever. I'm pretty poor at soldering, and I've no idea how to get a PCB printed, but this will be the project that motivates me to do it! Thank you for your work and I am watching this carefully!

nizmow wrote on 2024-09-17, 07:04:

Prolinea MT 4/50 mini tower

Curious how the module sits in the machine and where it mounts to. Do you have some close-ups?

Prototype boards are here, memory and logic IC's too. Still waiting for capacitors and resistors. At least the machine boots with the inserted module, so no shorts in ground / voltage plane. The mounting hole was almost 'guessed' correctly, a screw will already fit, but in the final design I will move the hole ever so slightly..

On a sidenote. Also received my POST analyzer, I've always wanted to flash the HP Vectra VL2 Bios and see at what step it fails, I'll do that too.. The HP bios is Phoenix based and supports 1MB of cache and it doesn't need the separate configuration utility, would be awesome to get this running. I'll open up a new thread once I have my upgrades working (adding cache, 3.3V support , 128MB and a modified bios)..

sander wrote on 2024-09-24, 17:48:

Curious how the module sits in the machine and where it mounts to. Do you have some close-ups? […]
Show full quote

nizmow wrote on 2024-09-17, 07:04:

Prolinea MT 4/50 mini tower

Curious how the module sits in the machine and where it mounts to. Do you have some close-ups?

Prototype boards are here, memory and logic IC's too. Still waiting for capacitors and resistors. At least the machine boots with the inserted module, so no shorts in ground / voltage plane. The mounting hole was almost 'guessed' correctly, a screw will already fit, but in the final design I will move the hole ever so slightly..

The attachment IMG_20240924_193531.jpg is no longer available

The attachment IMG_20240924_193202.jpg is no longer available

On a sidenote. Also received my POST analyzer, I've always wanted to flash the HP Vectra VL2 Bios and see at what step it fails, I'll do that too.. The HP bios is Phoenix based and supports 1MB of cache and it doesn't need the separate configuration utility, would be awesome to get this running. I'll open up a new thread once I have my upgrades working (adding cache, 3.3V support , 128MB and a modified bios)..

It is beautiful... just absolutely astounding and beautiful.
I can't wait to see the chips and bits on it. Or seeing screen shots of it showing up in that compaq windows 3.1 looking environment. 256k! That was never possible with released hardware.

Here are some photos of the Prolinea MT 4/50. Just taking it apart for cleaning! Very spacious design, and the same cache port up top.

ah, so it turns out retroweb has redundant entry for presario 800 https://theretroweb.com/motherboards/s/compaq-presario-800 as it uses same board as MT line https://theretroweb.com/motherboards/s/compaq-prolinea-mt

nizmow wrote on 2024-09-28, 03:35:

Here are some photos of the Prolinea MT 4/50. Just taking it apart for cleaning! Very spacious design, and the same cache port up top.

Thank you! So there is no bracket to attach the cache module to? It looks like the module will fit, but I would like to be sure if the protruding edge will fit. Can you measure how much room you have from the top of the cache socket?