Okay, so I finally got the NCR controller and am now trying to get it
to work.  The first problem is that the driver thinks it's a
single-ended controller, when it should be differential:

ncr0 at pci0 dev 9 function 0: ncr 53c825 fast10 wide scsi
ncr0: interrupting at irq 12
ncr0: minsync=25, maxsync=206, maxoffs=8, 16 dwords burst, normal dma
fifo
ncr0: single-ended, open drain IRQ driver
ncr0: restart (scsi reset).

Looking at ncr.c, it seems that the differential test is commented
out:

#ifdef  SCSI_NCR_SYMBIOS_COMPAT
        if (!(np->rv_gpcntl & 0x01))
                np->features |= FE_LED0;
#if 0   /* Not safe enough without NVRAM support or user settable
option */
        if (!(INB(nc_gpreg) & 0x08))
                np->features |= FE_DIFF;
#endif
#endif  /* SCSI_NCR_SYMBIOS_COMPAT */

Will Bad Things happen if I uncomment that?  Should I add FE_DIFF to
the flags below instead?

> {NCR_825_ID, 0x00,     "ncr 53c825 fast10 wide scsi",          4,  8, 4,
> FE_WIDE|FE_ERL|FE_BOF}