Here is a BIOS dump straight from the chip from my T8900D based card : http://www.tmeeco.eu/BitShit/PCschit/T8900D.BIN

Thanks, it's a byte-for-byte match with what I downloaded. Good to know I'm supposed to write as-is. I'll order a 256Mbit EPROM and play around with the jumpers, but I'm thinking this one's a goner.

I just now notice the card is 8900D-R, and that R should mean there is an internal ROM. Are you sure the EPROM was harvested from the card (i.e solder work was seen on the vias where you put the socket on) ?

I have one of these cards, the ROM is indeed internal, so probably installing a chip won't change anything. Mine doesn't even have the BIOS socket soldered either, just empty pads.

I recommend to check the jumper settings, I have the manual so here they are (* is the default setting for each, you may try those first).

First the 3 jumpers at the top, it should work regardless of the setting:

J1: Enable second stage zero-wait state (open) / *Disable second stage zero-wait state (closed)
J7: Non-interlaced display (open) / *Interlaced display (closed)
J8: Autodetect 8-bit or 16-bit BIOS (open) / *8-bit BIOS (closed)

Next, J6 and J10 should be kept open and closed respectively to run on a 16-bit slot, you need to add 3 unpopulated jumpers to run on an 8-bit slot and even then it's kind of pointless since it doesn't run on XT-class machines (internal BIOS probably has 286+ code):

J6: *16-bit ISA (open)
J10: *16-bit ISA (closed)

The 0WS jumper (J2)doesn't seem to work for me, so I keep it open.

Finally keep J3 open unless you have 256KB of video RAM.

[..] it's kind of pointless since it doesn't run on XT-class machines (internal BIOS probably has 286+ code):[..]

XT class machines can handle 80286 instructions just fine if an 80188/80186 or NEC V20/30 is installed.
With the exception of Protected-Mode or NMI related instructions.

Likewise, an 80286 can handle 386 Real-Mode instructions if EMU386 is loaded.

But that's not really helpful here, I admit.

One of my Trident 8900 cards doesn't work in a 286, too, while another one does (8900S?).
The BIOS was from circa 1991 in each case, I think.

Oh. And I never got one of the cheaper Trident 9000 to work on 286es.
Not sure if that's helpful, either. Sorry. 🙁

Edit: Since a few years, the Trident 8900D is considered to be a worthy rival to the Tseng ET-4000AX.
So maybe it makes sense that it contains 386 instructions for performance reasons? 🤷‍♂️

Edit: Also, some AT motherboards do have a single 8-Bit slot for very old expansions card that won't fit in an 16-Bit slot.

Jo22 wrote on 2022-05-19, 00:02:

XT class machines can handle 80286 instructions just fine if an 80188/80186 or NEC V20/30 is installed. With the exception of Pr […]
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[..] it's kind of pointless since it doesn't run on XT-class machines (internal BIOS probably has 286+ code):[..]

XT class machines can handle 80286 instructions just fine if an 80188/80186 or NEC V20/30 is installed.
With the exception of Protected-Mode or NMI related instructions.

Likewise, an 80286 can handle 386 Real-Mode instructions if EMU386 is loaded.

But that's not really helpful here, I admit.

One of my Trident 8900 cards doesn't work in a 286, too, while another one does (8900S?).
The BIOS was from circa 1991 in each case, I think.

Oh. And I never got one of the cheaper Trident 9000 to work on 286es.
Not sure if that's helpful, either. Sorry. 🙁

Is one of yours has 2 eeproms in two sockets that works in your 286?

Cheers,
Edit: Since a few years, the Trident 8900D is considered to be a worthy rival to the Tseng ET-4000AX.
So maybe it makes sense that it contains 386 instructions for performance reasons? 🤷‍♂️

Jo22 wrote on 2022-05-19, 00:02:

Edit: Since a few years, the Trident 8900D is considered to be a worthy rival to the Tseng ET-4000AX.
So maybe it makes sense that it contains 386 instructions for performance reasons? 🤷‍♂️

Now that I think about it, the XT machine in which I tested my Trident has a V20, so the BIOS probably has 386 instructions as you say. The card worked fine on an 8-bit slot of a 386SX.

pentiumspeed wrote on 2022-05-19, 00:07:

Is one of yours has 2 eeproms in two sockets that works in your 286?

Cheers,

Hi, it's this one. It has two EPROMs. I could dump them if that's helpful.
Not sure if they compatible with the 8900D, though.
Tiido likely knows more aboutthe matter than me.
All I really know is that the 88xx, 89xx, 90xx prefixes are references to the years of each chip's release/creation.
The suffix likely is used for different revisions, RAM types etc.

Success! Closing J10 was all that was needed. J6 open, J10 open wasn't a valid configuration.

There was an instruction sheet in the box. Should have though to check jumper settings, but my mind went right to the unpopulated ROM. There wasn't a socket originally and it looked pristine, but I just figured the previous owner did a really good job removing it.

Thanks!

Very good, enjoy the card ~

I found different pin-out manual for 8900D :

FYI : Two numbers show what mode is enabled for BIOS/ISA bus.
"8" means 8-bit and "16" means 16-bit (more is better)
"Foff" means you aren't using FIFO (enable for higher speed, may present compatibility/stability problems with some MBs)

I have a Trident card with the same chip. It doesn't boot the machine. I understand that it contain a embedded rom. there is some way to check or rewrite the embedded rom/eeprom? or may be just a rom ? someone has some idea?
My one has discrete 32 ic 256kb memory. I think that memory or DAC were bad. Of memory fail, may the board hold booting maybe?