Here in the US AT27C512R chips in 28-pin DIP format are $2.80 apiece. Those chips are one-time programmable.
28-pin chips can be in multiple capacities, 512 kilobits (64 KB) being the biggest.
If the video BIOS is smaller than that, it's best practice to concatenate multiple copies of it to fill the whole chip.
The TL-866 II is popular and works, I don't know if it is any different than what you have proposed.

Thanks for the reply! Based on the BIOS file from the VGA museum the BIOS is 32KB, so I'm assuming this would be AT27C256R like this would be OK?

https://au.mouser.com/ProductDetail/Microchip … q%2FqQ69Oz0uUwJ

Yeah that's perfect. Just bare in mind it's a one time programmable chip. So don't fuck up your settings in the programmer software

maxtherabbit wrote on 2021-11-14, 03:40:

Yeah that's perfect. Just bare in mind it's a one time programmable chip. So don't fuck up your settings in the programmer software

Don't worry I never make mistakes 😂

I'd better buy a few chips.

Thanks very much for the help guys 👍

badmojo wrote on 2021-11-14, 04:05:

I'd better buy a few chips.

Or consider using EPROMs (UV Erasable PROMs) or EEPROMs (electrically erasable PROMs) instead of OTPROMs (one-time programmable ROMs).
If you have a stash of defective or otherwise worthless boards/cards, then it is highly likely that one or more of these have such a thing which can be reused.

badmojo wrote on 2021-11-14, 04:05:

Don't worry I never make mistakes 😂

I'd better buy a few chips.

😂 I can very much relate to this.

That's very interesting, are you willing to share both bios?
The one with higher performance and the other?
You can take the dump with nssi program.

Thank you

Nemo1985 wrote on 2021-11-14, 09:44:

That's very interesting, are you willing to share both bios?

Sure I'm happy to share them if I get that far - I've ordered the unit so I'll see how I go.

Don't get me wrong the performance difference is tiny, but it's measurable and therefore enough to keep me up at night 😋

badmojo wrote on 2021-11-14, 11:12:

Nemo1985 wrote on 2021-11-14, 09:44:

That's very interesting, are you willing to share both bios?

Sure I'm happy to share them if I get that far - I've ordered the unit so I'll see how I go.

Don't get me wrong the performance difference is tiny, but it's measurable and therefore enough to keep me up at night 😋

And that's because interesting. 😀
Anyway to make a dump of the bios you do not need anything special, with nssi, it makes the dump from the running pc. No programmer neded.

Thank you kindly.

Nemo1985 wrote on 2021-11-14, 11:30:

And that's because interesting. :) Anyway to make a dump of the bios you do not need anything special, with nssi, it makes the d […]
Show full quote

badmojo wrote on 2021-11-14, 11:12:

Nemo1985 wrote on 2021-11-14, 09:44:

That's very interesting, are you willing to share both bios?

Sure I'm happy to share them if I get that far - I've ordered the unit so I'll see how I go.

Don't get me wrong the performance difference is tiny, but it's measurable and therefore enough to keep me up at night 😋

And that's because interesting. 😀
Anyway to make a dump of the bios you do not need anything special, with nssi, it makes the dump from the running pc. No programmer neded.

Thank you kindly.

Agreed. I would suggest that your temporarily disable Mainboard BIOS & Video card BIOS shadowing in the CMOS setup before dumping the BIOS with NSSI.

Dumping PCI video card BIOSes with NSSI is not reliable. The EPROM on the PCI cards often contains more data than the card exposes to the bus.

Some cards also have shuffled bit and/or address order, Trident ones for example.