Garrett W wrote on 2021-06-01, 13:28:

Kinoli wrote on 2021-06-01, 13:03:

megatron-uk wrote on 2021-06-01, 10:34:

With respect to the CL 5428, it's a really good Dos gaming chip - I don't know if your board has it connected via ISA or local bus; if it's ISA and you have a VLB/PCI slot free, then a VLB/PCI card would be a good upgrade (the ISA bus is a big bottleneck for games like Doom that push a lot of pixel data). If, however it's it's already a VLB connection (either in a slot or embedded on the motherboard itself) then you'll not gain much for changing to another card, certainly not for Dos games.

The video card is soldered onboard, so I imagine it is via local bus? I only have ISA-16 slots, that's where my Sound Blaster Network adapter goes. If I can squeeze a little bit of performance out of the machine changing the CPU, I'll definitely do that.

No, unfortunately that's not guaranteed. We'll have to take a look at the documentation and see how it is connected. My bet is that it is ISA, which would in turn make Doom run a lot worse and perhaps further explain your disappointment. I tried looking around with the model you provided, but I couldn't find it, are you sure it's the HP Vectra 486/25M? Could you take a couple of photos of the case as well as the internals, mainly the motherboard? That would help immensely.

For some reason, I got confused writing the vectra model, I will edit my op. It is a 486/25VL.
Here you have the photo. If this is not enough, I can do a close up on the graphics part.

About the overclocking, my father-in-law has a 486DX/33 and a 486DX2/66 for some reason, so I will be using the DX2 to upgrade the CPU. I will have to look up a heatsink that fits , and probably a fan too.

According to your motherboard chipset datasheet VL82c480 your system is ISA only 🙁
But CL-GD5428 is fast ISA graphics chipset and you can probably double its memory throughput supplying ZIP memory to empty sockets (between CPU and graphics chip).
To even more boost system performance you can solder sockets for cache memory (like on this picture).

zyga64 wrote on 2021-06-02, 06:14:

According to your motherboard chipset datasheet VL82c480 your system is ISA only 🙁
But CL-GD5428 is fast ISA graphics chipset and you can probably double its memory throughput supplying ZIP memory to empty sockets (between CPU and graphics chip).
To even more boost system performance you can solder sockets for cache memory (like on this picture).

I see. I didn't know about ZIP memory, but it seems easy enough. Should one of these work?
https://www.ebay.es/itm/334021265709?hash=ite … HUAAOSw~yRgBIm5
https://www.ebay.es/itm/144058236960?hash=ite … L0AAOSwfFBf92bw

About the cache memory, could I buy some sockets (like these ones) so I don't have to solder each cache pin to the MB? I know that I have to solder each socket, but I think it will be easier in the long run.

In the parts list, it says this: "Second Level Cache Memory Module: 128 KB Cache Memory Module - D3029A". I looked in the internet for it and found nothing. Any ideas?

Now you have 512kB graphics memory: 4 chips in organization of 4 x 256bit v53c103. I suppose you have to buy 4 ZIP chips of the same organization:
ebay search

You are right regarding cache sockets. For cache memory just buy 32kBx8 chips just like on the picture I linked before, but...
I'm not sure about three missing chips below SIMM sockets. One of them (bigger, I can't see clearly its description) may be TAG SRAM needed for cache functioning.

zyga64 wrote on 2021-06-02, 07:26:

Now you have 512kB graphics memory: 4 chips in organization of 4 x 256bit v53c103. I suppose you have to buy 4 ZIP chips of the […]
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Now you have 512kB graphics memory: 4 chips in organization of 4 x 256bit v53c103. I suppose you have to buy 4 ZIP chips of the same organization:
ebay search

You are right regarding cache sockets. For cache memory just buy 32kBx8 chips just like on the picture I linked before, but...
I'm not sure about three missing chips below SIMM sockets. One of them (bigger, I can't see clearly its description) may be TAG SRAM needed for cache functioning.

Thanks for the links, I'll take a look.

About the cache memory, the book says this:
CACHE MEMORY
128 KB of second-level cache memory may be installed (except in the 486/25VL). All four chips must be installed.

My model is 486/25VL, so it seems that the missing chips could be the ones needed for cache functioning, as you said. I don't know if soldering them in there will be enough, maybe it's better to leave it like that. What do you think?

Kinoli wrote on 2021-06-02, 09:05:

Thanks for the links, I'll take a look. […]
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Thanks for the links, I'll take a look.

About the cache memory, the book says this:
CACHE MEMORY
128 KB of second-level cache memory may be installed (except in the 486/25VL). All four chips must be installed.

My model is 486/25VL, so it seems that the missing chips could be the ones needed for cache functioning, as you said. I don't know if soldering them in there will be enough, maybe it's better to leave it like that. What do you think?

I would take a risk 😀 Moreover, I would try to add 8 memory chips for 256kB cache - max supported by chipset. Question is - will it be properly initialized by BIOS ? I think there is good chance of it because there is place for 8 memory chips 😀

On the other hand I have 486 motherboard (based on Intel 420EX chipset) where adding cache makes almost no difference in performance.

zyga64 wrote on 2021-06-02, 09:26:

Kinoli wrote on 2021-06-02, 09:05:

Thanks for the links, I'll take a look. […]
Show full quote

Thanks for the links, I'll take a look.

About the cache memory, the book says this:
CACHE MEMORY
128 KB of second-level cache memory may be installed (except in the 486/25VL). All four chips must be installed.

My model is 486/25VL, so it seems that the missing chips could be the ones needed for cache functioning, as you said. I don't know if soldering them in there will be enough, maybe it's better to leave it like that. What do you think?

I would take a risk 😀 Moreover, I would try to add 8 memory chips for 256kB cache - max supported by chipset. Question is - will it be properly initialized by BIOS ? I think there is good chance of it because there is place for 8 memory chips 😀

On the other hand I have 486 motherboard (based on Intel 420EX chipset) where adding cache makes almost no difference in performance.

I see. Then, I'll probably try the upgrade with the DX2/66 and the VRAM and if it's not enough, I'll also do the cache. Where do you think I could look up which chips do I need to solder in the three slots empty slots?

Also, these should be allright for the VRAM?
https://www.ebay.es/itm/253121819742?hash=ite … I0AAOSwf-xZpTZ8

I also found these which are faster but in the datasheet only appears 85/100/120 ns as MAX RAS Access time and I don't know if these would work.
https://www.ebay.com/itm/224229802596?hash=it … TAAAOSwCatfqyx5

Thanks for everything!

ZIP memory chips should be 20 pin, that's for sure. Organization should be 256k x 4bit.
Timing ? Chips onboard are 45ns. It is hard to find ZIP memory "that fast "

Cirrus Logic mentions 70ns in specification (from here) for 45MHz memory clock. I think we can asume 60ns for 50MHz MCLK (which is max for CL-GD5428).
You can search HM514256 or MT4C4256 or KM44C256 (or equivalent from other manufacturers) in ZIP package.

Regarding missing chip for cache.
I think I deciphered bigger missing chip of the three. It is MT5C2889 32kx9bit SRAM - so it is TAG memory chip (needed for cache).
Maybe this one will work if pinouts are the same.
The other two are common 74F373 chips.

zyga64 wrote on 2021-06-02, 11:48:

ZIP memory chips should be 20 pin, that's for sure. Organization should be 256k x 4bit. Timing ? Chips onboard are 45ns. It is […]
Show full quote

ZIP memory chips should be 20 pin, that's for sure. Organization should be 256k x 4bit.
Timing ? Chips onboard are 45ns. It is hard to find ZIP memory "that fast "

Cirrus Logic mentions 70ns in specification (from here) for 45MHz memory clock. I think we can asume 60ns for 50MHz MCLK (which is max for CL-GD5428).
You can search HM514256 or MT4C4256 or KM44C256 (or equivalent from other manufacturers) in ZIP package.

Regarding missing chip for cache.
I think I deciphered bigger missing chip of the three. It is MT5C2889 32kx9bit SRAM - so it is TAG memory chip (needed for cache).
Maybe this one will work if pinouts are the same.
The other two are common 74F373 chips.

Thank you very much! I will take a look at everything and I'll see if in the future I'll put it in the machine. For now, I have some things to setup, so that's good.

Yesterday I managed to install a GOTEK Floppy Emulator with FlashFloppy and trying to install the MS-DOS 6.22, my OS only recognizes 500MB instead of the total my SD hard has. I tried with an 8GB SD Card and 32GB MiniSD (with an adapter) and using the autodetect function in the bios, the disk is detected with the correct size. Strangely , when I format the SD card using a MS-DOS in a virtual machine, the partition (which is usally 2GB) is recognized, although if I have more partitions, I can only see the first one. I used WHATIDE and the values seem correct. Maybe the adapter is not working properly?

Here you have some photos, if you want to take a look. Thanks!

Edit:
Looking at this page (https://www.win.tue.nl/~aeb/linux/Large-Disk-4.html) it seems my bios is very old and only can use 504MiB. It's strange that via the VM it can fully grasp a full 2GB partition, but well... I'll probably stick with the 2GB partition and that's it.

Have you tried ez-drive for getting around the bios hdd size limitation as i had suggested earlier?