syntax for hex2bin

Are you saying that the syntax given at http://www.keil.com/download/docs/7.asp is not correct?

Syntax: HEX2BIN [/option] hexfile [binfile]

hexfile is the Intel HEX input file
binfile is the binary file to create

option  may be any of the following

  /Ln     Binary file length
  /Pn     Pad data for binary file
  /On     Address offset (to add to HEX records)
  /M      Merge data into existing BIN file
  /Q      Quiet mode (no statistics are displayed)
  /X      Don't process ext. segment/linear address records

  /?      This help text

Are you saying that the syntax given at http://www.keil.com/download/docs/7.asp is not correct?

Syntax: HEX2BIN [/option] hexfile [binfile]

hexfile is the Intel HEX input file
binfile is the binary file to create

option  may be any of the following

  /Ln     Binary file length
  /Pn     Pad data for binary file
  /On     Address offset (to add to HEX records)
  /M      Merge data into existing BIN file
  /Q      Quiet mode (no statistics are displayed)
  /X      Don't process ext. segment/linear address records

  /?      This help text

If myfile.hex has gaps and I want to keep the gaps in erased state I'd fill them with FF.

Both
HEX2BIN /f0xff myfile.hex
and
HEX2BIN /f255 myfile.hex
fill the gaps with 00 and not FF as I expected.

found a better one at
sourceforge.net/.../showfiles.php

But there is no "/f" option listed in the syntax for Hex2Bin - did you try "/P"...?