
 1. About XCDROM32

 XCDROM32 is a JLM based on Jack R. Ellis' XCDROM Ultra-DMA CD-ROM driver.
 It supports PCI IDE controllers running in "legacy" or "native" mode.


 2. Usage

 To load the driver, add the following line to your CONFIG.SYS:

   DEVICE=JLOAD.EXE XCDROM32.DLL [options]

 Options are:

  /32  use 32bit-IO in "PIO mode". This might not work with all devices,
       but if it does, it usually gives a speed boost for that mode.
  /AX  disable "audio" functions.
  /D:name  set device name. If this option is missing, the default device
       name is "XCDROM$$"
  /F   "fast", uses DMA "scatter/gather" lists to allow transfers which 
       cross a physical 64 kB address boundary. Might not work with all
       controllers.
  /L   limits DMA to "low memory" below 640 kB.
  /Mn  set/restrict UDMA mode to n (0 <= n <= 7).
  /Q   quiet mode.
  /UX  disables UltraDMA for all drives and uses "PIO mode" generally.
  /W   handle (non-UDMA) drives which are capable of Multiword-DMA.


 3. Details

  XCDROM32 has 3 modes of operation:

  1. "direct" mode: the target address is used for DMA input. This usually
     is the fastest way and is used whenever possible.
  2. "buffered" mode: the VDS DMA buffer is used for DMA input, then the
     content is copied to the target address. This mode is used if "direct
     mode" can't be used because target address is not aligned properly
     or - if option /F isn't set - because the target region crosses a 64 kB
     boundary. On modern CPUs the additional time needed for the memory copy 
     should be negligible.
  3. "PIO" mode: input is done without DMA. This mode should work with any
     IDE controller and CDROM/DVD. It is used if
     - /UX option is set.
     - the IDE controller doesn't support PCI Busmaster DMA.
     - the CD-ROM/DVD device is not in UDMA mode or /W option is set, but
       CD-ROM/DVD device has no valid Multiword-DMA mode set.
     - "buffered mode" cannot be used because VDS DMA buffer isn't
       accessible or is too small.


  4. License

  XCDROM32 is released under the GNU GPL v2. See GNU_GPL.TXT for details.

