According to the datasheet of the UMC chip, CS2 (pin 38) enables the parallel port when low, so after taking a backup which you just did 😉 you could remove all the jumpers, find out which pin now covered by a jumper is connected to pin 38 of the chip, and find if any others that didn't have a jumper do - these will be the other options, if any, for the parallel port 😀

This looks like it might the same card: https://stason.org/TULARC/pc/hard-disk-floppy … s-SUN-5241.html

That says a jumper on JP6 A (from the silkscreen that's pins 1&6) should make it LPT1.

snufkin wrote on 2024-04-12, 16:39:

This looks like it might the same card: https://stason.org/TULARC/pc/hard-disk-floppy … s-SUN-5241.html

That says a jumper on JP6 A (from the silkscreen that's pins 1&6) should make it LPT1.

Unfortunately, it's not that one. Putting a jumper on JP6-A (or JP6-A+B) disables the parallel port. Putting a jumper on JP6-B doesn't seem to do anything. 🙁

Ryccardo wrote on 2024-04-12, 14:32:

According to the datasheet of the UMC chip, CS2 (pin 38) enables the parallel port when low, so after taking a backup which you just did 😉 you could remove all the jumpers, find out which pin now covered by a jumper is connected to pin 38 of the chip, and find if any others that didn't have a jumper do - these will be the other options, if any, for the parallel port 😀

But pin 38 only enables or disables the parallel port, doesn't it? There are three possible addresses plus disabling the parallel port, so that's a total of four options. How can this be configured with just one pin?

the TULARC doc says it is controlled with 2 jumpers. JP6 A and B.

That is logically 4 states.

1-0 = LPT1
0-1 = LPT2
0-0 = DISABLE
1-1 = INVALID/NOT DEFINED

popcalent wrote on 2024-04-13, 09:43:

snufkin wrote on 2024-04-12, 16:39:

This looks like it might the same card: https://stason.org/TULARC/pc/hard-disk-floppy … s-SUN-5241.html

That says a jumper on JP6 A (from the silkscreen that's pins 1&6) should make it LPT1.

Unfortunately, it's not that one. Putting a jumper on JP6-A (or JP6-A+B) disables the parallel port. Putting a jumper on JP6-B doesn't seem to do anything. 🙁

Can you check if the other jumpers match, particularly the COM port base address and IRQ? Everything else (like jumper names and approximate positions) seems to match nicely. So if the other jumpers match the details on that page then maybe there's a board fault. Maybe wherever JP6-B goes is stuck as though the jumper is on so the jumper doesn't do anything. That would make putting a jumper on A undefined, which maybe disables the port. There are also two jumpers, JP5 B&C that are listed as do no alter, and maybe someone altered them?

Lot of maybes there...

popcalent wrote on 2024-04-13, 09:45:

But pin 38 only enables or disables the parallel port, doesn't it? There are three possible addresses plus disabling the parallel port, so that's a total of four options. How can this be configured with just one pin?

Address decoding is external, if you look at the datasheet of the UMC you'll see an example of how it can be done (but your card doesn't implement it in the same way so disregard the jumpers shown there) 😀

Some of the smaller chips will generate a logical 0 somewhere when the CPU requests I/O on a port corresponding to "LPT1"*, some related logic will do that for "LPT2"*, some further will do that for "LPT3"*, and the jumpers will connect either to pin 38!

Well, on a full reference design that is - the card can implement any selection among the 3 addresses, while unlikely it could have only one or more likely two…

* whatever that means - there's a natural priority for the 3 standard parallel port addresses, but if you only have "the third one" the BIOS will call that LPT1 anyway

wierd_w wrote on 2024-04-13, 10:09:

the TULARC doc says it is controlled with 2 jumpers. JP6 A and B. […]
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the TULARC doc says it is controlled with 2 jumpers. JP6 A and B.

That is logically 4 states.

1-0 = LPT1
0-1 = LPT2
0-0 = DISABLE
1-1 = INVALID/NOT DEFINED

Yes, but how does that go into just one pin of the IC? Anyway, I tried all possibilities with those two jumpers and it's either 0x278 or disabled.

I tried everything on JP6. No jumpers = 0x278. If I put a jumper on JP6A, there's no parallel plot. If I put a jumper anywhere else in JP6, the address is 0x278. I'm starting to think there's no way to change the port address.

Also, I used a tester in continuity mode, and there isn't anything in JP6 that is directly connected to pin 38 of the IC.

Edit: I just tried all combinations of JP5 with JP6 set to my default, and all combinations of JP6 with JP5 set to my default. All I could do was enable/disable the parallel port, one of the serial ports, or all serial ports. There's a lot of combinations that do the same thing. None changes the address of the parallel port....

Normally, the first parallel port is a 378h and the second is at 278h.
However, if an MDA card w/ an integrated parallel port at 3BCh is in the system, everything gets moved up (3BCh, 378h, 278h)..
So the LPT1 and LPT2 naming scheme on the PCB or in the manual don't apply, really. To the hardware, there are just port adresses. The BIOS assigns LPTx at will.

I got a new card with just one LPT port from eBay. Now I have two LPTs: one on 0x278, and one on 0x378.