[Unattended] format problem

[<Ber...@fr...>]

I'm in early stages of testing unattended on a laptob with an e100b network
interface.
(I use the e100b image)
I've partionned the disk to have a 2Gb C:, but format fails with
Call to int 0x21, 0x440d 0x60, failed error 0f.
Do I need to use this specific format command (a GNU one) or may I replace
it by the 6.20 MS version?
more generally, may I rebuild the boot diskette using a different Dos
version?