[JohnBHanson]

The rom loads the boot sector.

The boot sector then loads the rest of cpm.

I actually have the same problem when I use

xbeaver gem925.cfg -o r

which uses simon

using -v -v option i.e.

xbeaver gem925.cfg -o r -v -v

gives the same error message - indicating it is looking for a side 1 header on
side 0 of the disk. i.e. the boot sector code fails to switch to the second side
of the floppy disk as it loads the operating system.

i.e. the floppy boot sector code is not compatible with a gm849 (Probably only
compatible with a gm829).

it does appear that you have a different floppy image to boot from now so I don't think I am reproducing the problem you now have.

Please note that xbeaver is capable of booting a hard disk without roms!
when a scsi card is encountered in the configuration xbeaver looks for and loads a boot sector and if the boot sector execution address
when a rom is loaded not at address 0 a jump is placed at address 0 to the start of the rom.

Also read only memory is *not* implemented in xbeaver rom contents are loaded into ram. Furthermore the use of the control line of
the cpu card serial port to page rom in/out is not supported.

it looks like you have loaded the mfb bios, but it is not running properly on your hardware...
The hang up could be that the loaded cpm cannot read a: (a: could mean a floppy or a hard disk depending on the bios loaded).

what is the current hardware configuration you are trying to boot?
Does the same configuration work with a real floppy rather than a gotec. Are you trying to install the gotek into your mfb machine or
into your rack system? What are you using for your hard disk (xebec or real scsi disk or something else?).

The hard disk xebec controller supports the scsi command to set the geometry of the hard disk - if you are working without a zebec
controller this command may not be supported. (I don't know).