floppy cable ? 😀

Nothing either changed 3 cable , everything I used was previously tested and subsequently tested on another mobo

Have you tried a different floppy controller or try your current controller in an other system?

chrismeyer6 wrote on 2021-04-14, 19:33:

Have you tried a different floppy controller or try your current controller in an other system?

yes swapped and retested 3 controller

Have you verified your bios settings?

faulty contact on DRQ2 (ISA pin B06) ? ( considering the board you're trying is the same board whose photo is on the uh19 site, which seem to have suffered some damage from battery leakage )
reasoning : floppy controller uses DMA channel 2 for data transmission.

weedeewee wrote on 2021-04-14, 21:33:

faulty contact on DRQ2 (ISA pin B06) ? ( considering the board you're trying is the same board whose photo is on the uh19 site, which seem to have suffered some damage from battery leakage )
reasoning : floppy controller uses DMA channel 2 for data transmission.

i will Inspect signal tomorrow..

I inspected a tested all signal possible but no result,

Now i changed the ram con figuration and the ram simm and have finally the right message if there are no floppy insert.
But if i insert a floppy give me new error , "Data error CRC failed"

if i try to format a floppy give "track 0 error"

Did you try disabling external cache?

I take it that originally the floppy emulator gave the same error as the physical drives. Is that still the case now that you're getting CRC errors? How do the RPM test and Alignment test in IMD behave?

I changed the KS83C206C with C&T 82C206 (i found this under the chip) and mobo continue have the same problem no signal on DRQ2 and DACK2 ,

Are you testing DRQ2 and DACK2 with a scope? Where excatly are you tapping into the signal, the ISA slots? Could be there is a broken connection between the '206 and ISA.
Look for 82C206 pinout/datasheet on the net, doesn't matter which brand, pretty much all of these have the same pinout. See if you can test the connection resistance between ISA and the chip - or, there might be some buffer chips in between.

Deunan wrote on 2021-05-29, 17:34:

Are you testing DRQ2 and DACK2 with a scope? Where excatly are you tapping into the signal, the ISA slots? Could be there is a broken connection between the '206 and ISA.
Look for 82C206 pinout/datasheet on the net, doesn't matter which brand, pretty much all of these have the same pinout. See if you can test the connection resistance between ISA and the chip - or, there might be some buffer chips in between.

Yes i'm testing whit oscilloscope , and only DRQ2 go UP for a little time
I check signals on chip and on ISA
I checked connection 3 times now i'm checking for the 4 time
Measured resistance of DAK Pin to ground and are all 180 Ohm.

And I forgot I also changed the oscillator 14.31818MHz

Are you sure the C&T C206 is good? C&T are notorious for defects and wouldn't work beyond rated frequency so I used different C206 from non C&T chipsets.

Cheers,

I am 100% sure it works I don't know, it comes from a motherboard with problems but the floppies even if badly read them Read Floppy content error

There was some info in this thread Re: 486 will not boot from floppy; will not read from floppy either about how the dma/irq signals might be multiplexed. If that's the case on your mainboard, it would indicate one of the logic chips might be broken, or have a broken trace to it.

i followed the post but is different scenario , no chip in the middle no multiplex , direct connection for DRQ and DACK signal

dataino.it wrote on 2021-05-29, 18:52:

Yes i'm testing whit oscilloscope , and only DRQ2 go UP for a little time

Did you check the signal level? Is it higher than 3V at least? It should be even better than that, above 4V.
You say it is only a short pulse? That is weird, it should be high as long as it takes for CPU/chipset to acknowledge the request.

dataino.it wrote on 2021-05-29, 18:52:

I check signals on chip and on ISA
I checked connection 3 times now i'm checking for the 4 time
Measured resistance of DAK Pin to ground and are all 180 Ohm.

180 is OK, I get even lower on my mobo (60 ohm) and it works. It's probably pulled low by a resistor pack near the last slot to keep the lines terminated and reflection-free.

Can you measure how long the DRQ pulse is? And what is the H voltage on DACK2? Maybe it's too low for H level and detected as L by the card, so it lowers DRQ before the '206 has any chance to react to it.