SWTPC hard disk issue

[roelof4]

MAME version

Mame 0.237b

System information

Windows 10, UK

INI configuration details

Emulated system/software

SWTPC (swtpc09d3)

Incorrect behaviour

Booting the SWTPC:
mame swtpc09d3 -hard1 wd0.chd -hard2 wd1.chd -fdc:0 8dsdd -flop1 UOS_3S_BOOT.mfi

results in a working UniFLEX system but without working hard disks. The disks were prepared with chdman:

chdman createhd -o wd0.chd -i wd0.dsk -chs 306,6,17 -s 512
chdman createhd -o wd1.chd -i wd1.dsk -chs 306,6,17 -s 512
floptool flopconvert uniflex mfi UOS_3S_BOOT.DSK UOS_3S_BOOT.mfi

PLEASE note that I had to alter the chdman commands to avoid fatal errors:
remove the -s 512 (sector size)

Floppy conversion worked fine and boots system but I can't get the hard disks to work. Even if I use an empty one and check.

chdman verify -i wd0.chd

gives good result.

I am aware there are two types of hard disks available with the DMF3 controller. The devices file only reports back with w0 (winchester).
Any help is welcome!

Thanks.

Expected behaviour

Expected behaviour would be to see a working hard disk available after booting.

Steps to reproduce

See above:
mame swtpc09d3 -hard1 wd0.chd -hard2 wd1.chd -fdc:0 8dsdd -flop1 UOS_3S_BOOT.mfi

Additional details

No response