problem at boot from doc2000-with grub

[jay.s at sohu.com]

hi
  I have managed to compile the kernel and the grub, now I can read/write the doc2000 and I also get the grub_firmware which is about 89664 bytes, but still I cannot make the doc boot itself up. Although a previous good how to tell me to doc_loadbios /dev/mtd0   grub_firmware, but I find the doc_firmware space is only about 49k bytes, this 88k one can not inserted into it. I've tried to use dformat5.1 /BDKL0:90k to change the firmware space but I met the old !=1 preblem, but dformat4.2 seems doesn't support the parameter, what shall I do then?
 I am using a doc-2000 in a pc104 SBC with phoenix bios.

thans
                                 jay