README file for the Linux DTC3180/3280 scsi driver.
  by Ray Van Tassle (rayvt@comm.mot.com)  March 1996
  Based on the generic & core NCR5380 code by Drew Eckhard
  
  SCSI device driver for the DTC 3180/3280.
  Data Technology Corp---a division of Qume.
  
  The 3280 has a standard floppy interface.
  
  The 3180 does not.  Otherwise, they are identical.
  
  The DTC3x80 does not support DMA but it does have Pseudo-DMA which is
  supported by the driver.
  
  Its DTC406 scsi chip is supposedly compatible with the NCR 53C400.
  It is memory mapped, uses an IRQ, but no dma or io-port.  There is
  internal DMA, between SCSI bus and an on-chip 128-byte buffer.  Double
  buffering is done automagically by the chip.  Data is transferred
  between the on-chip buffer and CPU/RAM via memory moves.
  
  The driver detects the possible memory addresses (jumper selectable):
  	CC00, DC00, C800, and D800
  The possible IRQ's (jumper selectable) are:
  	IRQ 10, 11, 12, 15
  Parity is supported by the chip, but not by this driver.
  Information can be obtained from /proc/scsi/dtc3c80/N.
  
  Note on interrupts:
  
  The documentation says that it can be set to interrupt whenever the
  on-chip buffer needs CPU attention.  I couldn't get this to work.  So
  the driver polls for data-ready in the pseudo-DMA transfer routine.
  The interrupt support routines in the NCR3280.c core modules handle
  scsi disconnect/reconnect, and this (mostly) works.  However.....  I
  have tested it with 4 totally different hard drives (both SCSI-1 and
  SCSI-2), and one CDROM drive.  Interrupts works great for all but one
  specific hard drive.  For this one, the driver will eventually hang in
  the transfer state.  I have tested with: "dd bs=4k count=2k
  of=/dev/null if=/dev/sdb".  It reads ok for a while, then hangs.
  After beating my head against this for a couple of weeks, getting
  nowhere, I give up.  So.....This driver does NOT use interrupts, even
  if you have the card jumpered to an IRQ.  Probably nobody will ever
  care.