Re: Re: UMB and 386/486 --> status of FreeDOS emm386 etc.

Hi, Bart almost answered everything asked by Alain already, so:

- all of UMBPCI HIRAM URAM RDOSUMB are hardware based: they cause RAM to
  be enabled in the holes of the ROM area. If your BIOS allows you to do
  this by configuration, at least one of those 4 gives you UMB without
  compatibility problems :-)
- an EMM386 "re-maps" RAM to the UMB area, which is done using protected
  mode. This needs a 386 but is not troubled by hardware details.
- Bart explained the VCPI thing, if you want to do FreeDOS emm386, provide
  VCPI for it... it will then be able to "let others in" to protected mode.
- Protected mode programs run with FDXMS and the like because FDXMS and the
  like do not let the CPU stay in protected mode: The only "P.M." thing they
  do is call a BIOS function for copying RAM beyond 1 MB (if they detect that
  the CPU is in real mode, they may alternatively switch to P.M. for that for
  a moment).
  So a protected mode program that emulates the (simple) BIOS copying inter-
  face or that takes care not to copy to/from XMS should have no problems.
- The "cousins" of UMBPCI mentioned above are all linked from the UMBPCI
  homepage, www.uwe-sieber.de ...
- Bart, may I remind you of the "driver memory limit" patch (needed to run
  DR emm386 for VERSION >= 5) and the "temp file name" patch (needed to run
  some weird DPMI implementations, it seems) ? I hope they become part of the
  new kernel.

Eric