Isn't it obvious from the printing near the jumper block marked "Jumper setting"?

Very nice card btw 😀

Edit: The manufacturer "Startech" is well known and reputed, still exists 😀

Yes the IRQ's are sort of easy to figure out. The addressing is going to be tricky, with a PAL coming off some of the address lines trial and error might be easiest way even with the W86C451 datasheet.
Based on one other picture of a Startech IO4S3P card appears the current jumpers are the default for IRQ and addresses....

this is my guess as to the address jumpers but figuring out which exact async ports and addresses are impossible without the now long gone original docs or trial and error....
the LPT ports appear easy to figure out 😀
Probably wrong but this is where I would start....

Horun got there first, but I'd already started drawing this, so thought I'd attach my guess as well:

Largely based on a mix of what I think are the default addresses and assuming that the address selection are in order, and that the existing jumpers are set for the defaults.

snufkin wrote on 2021-10-23, 22:59:

Horun got there first, but I'd already started drawing this, so thought I'd attach my guess as well:
IO4S3P_BaseAddressGuess.jpg

Largely based on a mix of what I think are the default addresses and assuming that the address selection are in order, and that the existing jumpers are set for the defaults.

Good guess, think your Async could be correct but disagree with the PTR ports, close inspection shows PTR3 above PTR1 silkscreen and then down by the IC you see another P which I assume is for PTR2
My main reason for that is because on the other card there is no PTR2 header and no jumpers for it either for Port or IRQ.
still is Great work !

Horun wrote on 2021-10-24, 00:18:

Good guess, think your Async could be correct but disagree with the PTR ports, close inspection shows PTR3 above PTR1 silkscreen and then down by the IC you see another P which I assume is for PTR2
My main reason for that is because on the other card there is no PTR2 header and no jumpers for it either for Port or IRQ.
still is Great work !

Fair point. I was assuming that the silkscreen meant PTR1 was at the bottom, PTR3 at the top, with an implied PTR2 in the middle. I, likely wrongly, ignored that lone 'P'. In my defence, I was influenced by the fact that reading it that way meant both the address ranges and port numbers were in order, at least for the parallel ports. After all 1) why would anyone put informative silkscreen under a component & 2) given the use of the PAL, why wouldn't the designer have ports and addresses all lined up nicely in order. Perhaps my bigger assumption is that the designer wasn't actively trying to make life difficult.

I wonder if removing the jumpers disables the port. Do you think that the 10 pin header at the back end of the board next to the 556 is a joystick/gameport header (with the 556 used to measure resistance of x/y stick position)? There's also a jumper just beneath the IRQ jumpers that might be labelled 'GAME' (the silkscreen is a bit difficult the read), could be enable/disable?. Slightly curious (but not enough to actually put the work in) how they got 3 parallel ports + game port out of 2 ST16C552, given the datasheet says they only support one parallel port/gpio.

Also, Bernkastel7734, in case you don't already know, I've just noticed that the back of the PCB looks to be damaged in places, particularly the end furthest from the back plate, could be worth checking out if the card's not working.

Not sure but think if jumpers for a PORT was removed then it would not work (or wander around just drawing power ??), not sure if it would disable totally but sound probable...
Yep I think that header and jumper is for the game port and the PCB damage is at the back bottom of the 556 so if it is used for signal checking/timing the game port probably does not work right now anyway.
Well is never made easy on those old cards 🤣. Look how they laid out the IRQ jumpers...could have put the 4 asyncs to right sets and PTR's to the left sets but that is too logical ;p
If I had not seen the other card picture I would have made lots of assumptions that were probably not correct 😀

So, card works. As far as talking about COM port. I don't need game port, since I have one on sound card. I was asking about jumpers because it reports to have 4 COM's and 3LPT's. So I wondered if could somehow disable ports I don't use.

Can't see anything that looks like it'd be a definite disable (except possibly for the game port). Maybe try removing all the jumpers for a port and see if it can still be accessed? There are a few resistor packs on the board, so I'm assuming that no inputs are being left floating, so it shouldn't damage the board. May have to apply some trial and error to work out which base address jumpers go with which port. If you do work it out, might be nice to document it here so if anyone else looks for the settings they can find it.