Danger Manfred wrote on 2023-08-22, 22:09:

1. Is this a GD5428 or GD5426 card now?!

This PCB can be used to build a graphics card with a GD5426 chip or with a GD5428 chip. The GD5428 is fully compatible, but slightly better. As your card has the newer GD5428 installed, it's a GD5428 card.

Danger Manfred wrote on 2023-08-22, 22:09:

2. Does this mean that the "main" and "secondary" MB can operate at different speeds from each other, so you would want to make the faster memory the "main" one?

No. The "main" MB is just the MB that is used first, and the "secondary" MB is used for data exceeding the first MB. They are always accessed at the same speed.

Danger Manfred wrote on 2023-08-22, 22:09:

3. If not, what reason would you have to make one the "main" memory over the other?

As already discussed in numerous threads on VOGONs, installing a second megabyte on CL-GF542x cards is only useful if you require lots of offscreen memory, huge virtual desktops, or like interlaced modes very much. The primary use case of this assembly instruction (it's not meant for modification of an existing card, but meant as an explanation how to populate the PCB with chips) is that the card builder can use whatever type of memory they have at hand. If they have 256k x 4 DIP chips, they would use the second variant, and build a card that can not be upgraded. If they have 256k x 16 SOJ chips, they would use the first variant. And if they happen to have DIP20 sockets and install them as well, the card with the SOJ chips can be upgraded by the user.

5426 and 8 share pinout and will work in place of each other. Only difference is in way how some stuff is accessed but it only concerns the windows driver pretty much and is irrelevant to gaming.

There is little point giving one of the cards that extra 1MB of memory, you only gain access to some useless interlaced higher resolution modes that you probably don't want to be using anyway. RAM upgrade is done by filling those DIP sockets with suitable DRAMs that are 80ns or faster. You need 4bit wide and 256Kbit sized (128KBytes per chip) memories such as GM71C4256 and uPD424256.

Thanks! So basically the card is an upgradeable GD5428 the way it has been assembled. It could be upgraded with a second MB of RAM and the chips should have at least 80ns speed.
Now I don't need any interlaced resolutions, however, "regular" higher resolutions would be nice if the card would be able to do them, as my CRT is an Eizo Flexscan F931 that supports resolutions up to 2048x1536p80, but also 1600x1200p104 or 1280x1024p121. Although on the other hand I doubt anything running on a 486 would even go that high except for the Windows GUI maybe.
But there is no performance impact on 1 vs 2 MB in games like DOOM or such?

Danger Manfred wrote on 2023-08-23, 07:43:

Thanks! So basically the card is an upgradeable GD5428 the way it has been assembled. It could be upgraded with a second MB of RAM and the chips should have at least 80ns speed.
Now I don't need any interlaced resolutions, however, "regular" higher resolutions would be nice if the card would be able to do them, as my CRT is an Eizo Flexscan F931 that supports resolutions up to 2048x1536p80, but also 1600x1200p104 or 1280x1024p121. Although on the other hand I doubt anything running on a 486 would even go that high except for the Windows GUI maybe.
But there is no performance impact on 1 vs 2 MB in games like DOOM or such?

zero gain when you update. Don't do it.

Danger Manfred wrote on 2023-08-23, 07:43:

Now I don't need any interlaced resolutions, however, "regular" higher resolutions would be nice if the card would be able to do them, as my CRT is an Eizo Flexscan F931 that supports resolutions up to 2048x1536p80, but also 1600x1200p104 or 1280x1024p121.

The GD542x series chips are too slow to display the contents of more than 1MB at 60 Hz. That's why the extra mode you gain (IIRC 1280x1024 at 256 colors and possibly some high- or true-color mode) will be provided as interlaced mode.

CoffeeOne wrote on 2023-08-23, 10:49:

zero gain when you update. Don't do it.

Well, that's not the answer I had hoped to hear, but the one I had to hear. Thank you!

mkarcher wrote on 2023-08-23, 11:06:

The GD542x series chips are too slow to display the contents of more than 1MB at 60 Hz. That's why the extra mode you gain (IIRC 1280x1024 at 256 colors and possibly some high- or true-color mode) will be provided as interlaced mode.

Sad but makes sense. I'll pass on that. Thank you for explaining!