SWTPC / CORSHAM floppy questions

[Wawavoun]

Hello,

I actually work on my 6809 Corsham system.
I have MS-S board in slot 0 and a diy FD-2 floppy interface in slot 1.
I use SBUG 1.8.

A Gotek jumpered S1 is connected to the flat cable (after the cables 10-12 crossing so acting as drive 0) and a real 3.5 floppy drive (a PC 1.44 mo drive) is connected before the crossing so as drive 1.

Flex291 or Flexnet (716 ko image) boot and work well from the Gotek. Also I can write to this drive from XBasic for example.

The problem I have is with newdisk.
I run "newdisk 1" to format the floppy in drive 1.
I use dual side, 80 tracks and double density.
The drive do a lot of job on the floppy. I assume he write on each track then he come back to track 0. At this moment after some seconds of silence i got a error "formatting aborted"...
I have tested two different drives (both working elsewhere) and several floppies (DD, not HD) with the same problem so I think the problem is not here.

If I replace the floppy drive by a second Gotek with a 716 ko image (same as the boot disk) then I can format, write and read...

Any idea where is the problem and/or how can I investigate ?

Thanks and regards.
Philippe

 

[VeryVon]

Is the 3.5 floppy drive terminated?

 

[Wawavoun]

With the ohmmeter yes. All pins connected to the floppy interface output (74LS06) show 1 kohm resistance with Vdd.

 

[VeryVon]

What happens if you put the 3.5 floppy after the twist without any other drives connected?

 

[Wawavoun]

Because 3.5 drive are hardwired to s1 if I do that it will become drive 0 and then I have no way to boot (at this moment I have only dsk gotek images).

 

[Wawavoun]

My floppy interface use a wd2797.

For the alignment datasheet say to set pin 29 to 1000 ns and pin 16 to 125 KHz.

Are these values right for all the hi/lo combinations on pin 5/8 and dden ?
Or should they be changed if one or both pins are high ?

Regards.
Philippe