SVD wrote on 2020-10-01, 21:52:

Is there a easy trick to make it recognize bank 1 as bank 0 so I can skip the soldering (for checking at least)

You might want to cut the /RAS1 trace going to the sockets of bank 1, and connect /RAS on those sockets to /RAS0, the /RAS pin on bank 0.

Interesting that this card carries its own 14.318180Mhz oscillator instead of using OSC from the ISA bus. Perhaps there are signal integrity issues with OSC on some motherboards?

[The GD-542x series has a PLL for generating all the various video and memory dot clocks from the single 14.318180Mhz clock input.]

mkarcher wrote on 2020-10-01, 22:09:

SVD wrote on 2020-10-01, 21:52:

Is there a easy trick to make it recognize bank 1 as bank 0 so I can skip the soldering (for checking at least)

You might want to cut the /RAS1 trace going to the sockets of bank 1, and connect /RAS on those sockets to /RAS0, the /RAS pin on bank 0.

Thanks! 😀, i did not think it would be that easy (if i find the right traces). I will most likely go that route then, if i dont choose to solder. It should be easy to revert if i find that the card works i guess 😀

SVD wrote on 2020-10-02, 11:15:

mkarcher wrote on 2020-10-01, 22:09:

You might want to cut the /RAS1 trace going to the sockets of bank 1, and connect /RAS on those sockets to /RAS0, the /RAS pin on bank 0.

Thanks! 😀, i did not think it would be that easy (if i find the right traces). I will most likely go that route then, if i dont choose to solder. It should be easy to revert if i find that the card works i guess 😀

You can get datasheets for 256x16K DRAMs and for the CL-GD5428 chips. Both indicate which pins are affected. On the CL-GD5428, /RAS1 is multiplexed with MA9, if I remember correctly, so best is to check the appendix about memory configurations. You will find the 4 * 256Kx16 DRAM (symmetrical) configuration there which is exactly the configuration used on your card. You don't have to bother whether your card uses dual CAS or dual WE RAM, because this choice does not affect the bank selection mechanism via the RAS pins.

If everything fails, I can rework that card and stick on some new RAM. Except for 2 pads (might be due to the picture) they all seem fine.

kdr wrote on 2020-10-01, 23:29:

Interesting that this card carries its own 14.318180Mhz oscillator instead of using OSC from the ISA bus. Perhaps there are signal integrity issues with OSC on some motherboards?

The question here to ask is: Is there any VL-Bus VGA card that doesn't come with its own osilator and uses OSC from the ISA bus? I have dozens of them and every single one has one.

I know only some early Sound Blaster cards or other ISA cards from 80's used OSC from ISA and they quickly switched to own oscilator. OSC from the motherboard is unreliable for almost anything.

mpe wrote on 2020-10-02, 20:45:

The question here to ask is: Is there any VL-Bus VGA card that doesn't come with its own osilator and uses OSC from the ISA bus? I have dozens of them and every single one has one.

That's good to know, thanks for the correction.

[My current 486 machine is a HP Vectra VL2 that has a CL-GD5428 on the motherboard, and the only oscillator on the board is the 14.318180Mhz OSC for the ISA bus.]