dunarea wrote on 2020-06-25, 09:43:

With the same MFM+floppy combo controller, I can run anything from the floppy drive but not from the MFM HDD. From the HDD only text mode apps.

Never had in the past such an issue.

Hi, can you run CheckIt! off the floppy disk ? If so, check the memory browser.
It's just a wild guess, but maybe the controller's ROM is conflicting with the memory location of the framebuffer.
Textmode appears on two positions, depending of the graphics card (CGA/MDA etc).
Perhaps that's why it works.

Anyway, it's just an idea. Maybe fellow vogons users can help figuring out the issue..

Good luck! 😀

I checked .
I'll abstaint to evaluate and leave it to more experienced guys.

Make sure the MFM controller card is set to standard settings that XT requires. The controller also has to be 8 bit as well.

Interrupt, rom address, and DMA address etc. Also use the low level formatter to pick interleave ratio so XT & DOS can process the sectors without falling behind. If 4.77MHz XT around 6:1, XT 8MHz, use 4:1 etc.

Yes, XT is very slow. Even 286 needed around 3:1 to 2:1 to work.

Cheers,

my stock clock 5150 with V20 has optimum read speed at 3:1, my XT 286 at stock clock is optimised at 2:1

The controller is an HC-100 Transteque with dynamic configuration. Jumperless.
I set the interleave to 6 on my V20 XT machine. Tried before 3, 4 to 1 interleave and symptoms were the same.
The xtidecfg executable runs well with his ANSI interface, and is big enough to span many cylinders. Other software, no. Not even edit.com.

What is strange is if I pull out the MFM controller and use only the XTIDE-CF card, everything is fine. It is like that BIOS has something better inside...

Found something...
The NEC D3142 hdd is for an ST412 interface. With buffered seek.
And I was trying to pair it up with various ST506 interfaces... All without buffered seek. Text mode software was accepting somehow this conflict, but other graphical interfaces, not.
Now, I need to find a suitable ST412 MFM interface.

Finally found a ST412 MFM interface... Now it works. Tested good with Prince of Persia.

This kind of information is hard to come by, as there are fewer and fewer ppl out there with this kind of expertise.
It took me many hours of reading over the net to come to this conclusion.
The link who took me to the solution: http://minuszerodegrees.net/hdd/st506_st412_interface.htm

So, don't mix newer kind of MFM drives with buffered seek with old type ST506 interfaces because they won't work.

Also, the information on this site is wrong:
https://stason.org/TULARC/pc/hard-drives-hdd/ … -MFM-ST506.html
Correct is:
Cylinders: 643
Controller : MFM / ST412

Hope it would be useful in the future.

That's good.

Very early MFM controllers requires non-buffered hard drives. But the later MFM controllers (these are the ones easy to find), that works with buffered seek have to use later hard drives. Vast majority of MFM hard drives out there even when I had them back in the day (cast off stuff), were buffered seek type. I was toying with them when I was younger, the parts were not working well, like the ST125 mfm needed a twist to start, etc, the dumb 286 motherboard fails, and cast off but working XT boards but it keep working for game. etc. TTL amber monitor.

At one time I had ESDI stuff even at 800MB. Slow still. IDE was the way to go. And SCSI wide is much better too.

Cheers,