"Do you consistently see the fault in the same place?"

 

No, this is random place. I test BOOT-PROM3 disk and try boot PC more time. Every time is a different place e.g.:

 

lba=1051, lba=1086, lba=1015

 

but if try boot PC without any floppy inserted to FDD have this log:

 

Booting from Floppy...
enter handle_13:
   a=00000201  b=00000000  c=00000001  d=00000000 ds=0000 es=07c0 ss=df80
  si=00000000 di=00000000 bp=00000000 sp=0000f930 cs=f000 ip=cb97  f=0202
disk_op d=0x000f5520 lba=0 buf=0x00007c00 count=1 cmd=2
Floppy_drive_recal 0
Floppy_enable_controller
handle_0e
handle_0e
WARNING - Timeout at floppy_wait_irq:206!
Floppy_disable_controller
Floppy_enable_controller
handle_0e
WARNING - Timeout at floppy_wait_irq:206!
Floppy_disable_controller
invalid basic_access:96:
   a=00000200  b=00000000  c=00000001  d=00000000 ds=0000 es=07c0 ss=df80
  si=00000000 di=00000000 bp=00000000 sp=0000f930 cs=f000 ip=cb97  f=0202
handle_0e
Boot failed: could not read the boot disk

 

enter handle_18:
  NULL
Booting from DVD/CD...