Help! I can’t find a manual 😭

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Electrical-Floor7879@reddit

Wow, an ASEM motherboard... that company is based a few kilometres from where i live. Is still active, producing industrial devices.

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Okay so removing the “spare” 8088 setting the dips as if XT and moving the JP1 jumper to B C or D gets the floppy to read known good 720K floppy but then nothing - it does respond to Ctrl-Alt-Del but nothing else - so there we are further than at the start 😁 but still guessing about settings, thanks everyone 👍

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AppropriateCap8891@reddit

OK, you need to get a 360k 5¼" floppy and boot from that.

Remember, there is no CMOS in this, and it will treat every floppy until DOS actually loads as a 360k drive.

Look into the DRIVER.SYS command, putting that in CONFIG.SYS with parameters will tell the computer what the actual capacity of a floppy is, but as a boot device it will not know how to read anything other than a 360k floppy.

https://www.infania.net/misc/dos622help/driver.sys.html

This is why 720s were typically used as a B drive in XT systems.

XTs are a very strange thing to work on unless you are familiar with them. As they have no CMOS, you are very limited in what you can do in many ways.

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bobdvb@reddit

What FDD are you using? Are you sure it works? Are you sure it's supported? If you're trying a 3.5in 1.44MB drive then it might not work?
Can you get an XT-IDE to test with? Or does it have an IDE controller you could use with a CF?

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AppropriateCap8891@reddit

Nothing but a 360k 5¼" drive will work as a boot drive. That is all that a standard XT can see out of the box, unless you have an advanced floppy controller card with it's own BIOS.

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Best-Negotiation1634@reddit

No IDE hd ribbon cable…. Looks like 5.25” floppy time.

Com port cards are necessary

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AppropriateCap8891@reddit

This is an XT, of course there was no IDE port.

MFM was pretty much universal, with the ST-225 being the most common. I built so damned many of those that DEBUG G=C800:5 is forever burned into my memory.

Unless you were willing to spend the money for SCSI, or one of those fancy "Hard Cards".

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LieboOSBA@reddit

Is it this?

https://theretroweb.com/motherboards/23132

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ifknot@reddit (OP)

It is but… retroweb has no documentation for it 😭

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Sample_And_Hold@reddit

The DIP switch configuration options should be common to all XT motherboards:

https://computercraft.com/docs/pcdip.shtml

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AppropriateCap8891@reddit

I would say common for 98% of them.

I did work with some very late model XTs in around 92-93 that were a bit different. 1 MB in chips on the motherboard for RAM. And the BIOS would only support two floppy drives, but you could assign them as 320 or 720. I forget the actual setting for those, I only built around 20 of those at the very end of the XT lifespan.

Some very late model XT systems were actually quite impressive. Especially with the NEC V33, those were damned near as capable as a 286, but worked in 8086 motherboards.

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LieboOSBA@reddit

At least you’ve got the model to go off to start googling with

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AppropriateCap8891@reddit

Honestly, I am a bit laughing at some of the responses here.

For floppy drives, make sure you are using double density drives. That means 360k drives, high density floppy drives generally will not work on an XT (and even 720k can be a pain at best to use as your boot drive).

Make sure your DIP switches are set properly. Good thing is that those are pretty universal on an XT, I can probably count on one hand the number of times I found non-standard ones.

What cards are you going to use with it? You are largely going to have to use 8 bit ISA cards, but there are some 16 bit ISA cards that will work in these old beasts. Specifically, a hell of a lot of old 16 bit VGA cards will work in an XT system.

And check those RAM chips. That is a late model board, so should have between 640k and 1 meg on board. It's only reporting 256k, so I suspect you have the wrong chips installed.

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KelFromAust@reddit

Can't honestly claim I ever had much trouble with a 720k boot drive.

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AppropriateCap8891@reddit

On an XT?

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Sample_And_Hold@reddit

XTs did support 720k drives, but they were still rare and expensive at the time, so they were not widely adopted. It was wiser to invest on a 20 or 30 MB hard drive instead.

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AppropriateCap8891@reddit

Yes, and no. And there was a reason they were almost impossible to use as a boot device.

It must be remembered, there is no CMOS on an XT, just dip switches where banks 7 and 8 were used to identify how many floppy drives were present (0-4). And when turned on, it would see every floppy as a 5¼" 360k drive.

The reason we could use a 720k floppy is because of the OS. You would have to enter the CONFIG.SYS and use the DRIVER.SYS command to identify the appropriate drive location and what the size of the drive actually was.

Here is an example:

DEVICE=C:\DOS\DRIVER.SYS /D:1 /F:2

The first parameter (/D) assigns actual drive location (in this case the second or "B" drive). The second parameter (/F) is where you identify the size of the drive capacity itself, in this case 2 is for a 720K 3½" disk.

Without assigning this in CONFIG.SYS, the computer would treat it as a 5¼" drive, no matter what the actual capacity was.

This is why it was pretty universal on an XT to assign the 720k drive to B, that way you could still boot from A if you need to.

The only other way around that I am aware is some floppy controllers had their own BIOS that you would access through a DEBUG command, and some could even handle high density drives. Or some very late model XTs that changed the 7 and 8 dip switches to assign the number of drives as well as if they were 360k or 720k.

But in a bog standard XT, you could not assign a 720k floppy as a boot device. Because it would not know it was a 720k drive until the DRIVER.SYS command was loaded as part of the CONFIG.SYS.

Not sure how many of these you worked on back in the day, but I worked on hundreds of them. Unless the floppy controller had their own BIOS onboard to configure the devices the system simply can not see them as anything other than a 360k drive. Remember, the load order is IO.SYS, MSDOS.SYS, then CONFIG.SYS, COMMAND.COM and finally AUTOEXEC.BAT.

And how in the hell can it load the first two files as well as the CONFIG.SYS and DEVICE.SYS from a 720K drive, if the system still thinks it's a 360K drive?

Here is a breakdown of DRIVER.SYS from DOS 6.22, but it was unchanged from when it was added in DOS 3.3.

https://www.infania.net/misc/dos622help/driver.sys.html

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KelFromAust@reddit

Yep.. Hercules graphics too.

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tes_kitty@reddit

You sure that SIEMENS 8088 belongs into that socket? I ask because next to it is a NEC V20 which is already a CPU. It's compatible to the 8088 while also being faster.

Check if that socket might be meant for a 8087.

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ifknot@reddit (OP)

🤦🏻‍♂️you genius! (It came this way) Well spotted

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tes_kitty@reddit

Did removing the SIEMENS 8088 make a difference in the way the board behaves?

Also... Which floppy controller do you use? The onboard one or one on a card?

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ifknot@reddit (OP)

🤔 I don’t think the bios matches the board? Boot announces ASEM 3011 board is ASEM 3006

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tes_kitty@reddit

Should still be able to use the floppy controller since it's in the same location on every PC.

Also the memory shown looks incorrent. The memory ICs on the board look like 41C4256 (256Kx4) and 6 of them which would be 768 KB.

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Sample_And_Hold@reddit

Also the memory shown looks incorrent. The memory ICs on the board look like 41C4256 (256Kx4) and 6 of them which would be 768 KB.

Looks like the DIP switches (currently all ON) are not properly configured: 3 and 4 ON means only one bank of memory, should be 3 and 4 OFF.

https://computercraft.com/docs/pcdip.shtml

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ifknot@reddit (OP)

No difference actually but now I have a spare 8088 😁my XT-ide is with a friend so I’ll get it later this week but this is super helpful 👍

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Critical-Advantage11@reddit

Did you just find the board, or the whole computer. If you just found the board, and are hooking up a floppy drive you had laying around it may be unsupported.

There were several types of 5.25 drives in the 80s. Also make sure the floppy connectors are clean and test it with another system if possible

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ifknot@reddit (OP)

It is but… retroweb has no documentation for it 😭