DAT Drives under SunOS 4.1.1

[Eugene D. Brooks III]

On a SPARC 1 running SUNOS 4.1 we managed to use an ARCHIVE Python DAT
drive in 1/4 inch streaming tape compatibility mode.  The Python is 100%
compatible with the ARCHIVE VIPER streamer tape, which happens to be a Sun
supported drive.  To support the drive we simply created a table entry in
st_conf.c identical to the one for the VIPER, except that the identifier
string was changed to ARCHIVE Python.  We used the DAT drive in this way
for about 6 months, but ran into trouble when we upgraded our SPARC 1 to a
SPARC 2 which requires SUNOS 4.1.1

We noted that some work had been done to st_conf, some of the identifier
strings had been changed in minor ways.  We did the usual hack only to
have the following error message appear on the console when we tried to
use the drive:

esp0:	ILLEGAL bit set
	State=SELECT Last State=FREE
	Latched stat=0x12<XZERO,CD> intr=0x40<ILL> fifo 0x20
	last msg out: <unknown msg 0xff>; last msg in: LINKED COMMAND COMPLETE
	DMA csr=0x96400210<EN,INTEN>
	addr=fff0000 last=fff0000 last_count=7
	Cmd dump for Target 4 Lun 0:
	cdb=[ 0x12 0x0 0x0 0x0 0x24 0x0 ]
	pkt_state 0x0 pkt_flags 0x9 pkt_statistics 0x0
	cmd_flags=0x5 cmd_timeout = 0
	Mapped Dma Space:
		Base = 0x444 Count = 0x24
	Transfer History:
		Base = 0x444 Count = 0x24

Driver then reported that several other targets were now Synchronous at
4.0 MB/s max transmit rate, as if the SCSI bus had been reset.  An EXABYTE
made the usual grinding noises as if the bus had been reset at the time.

Is there anyone reading this list that has some experience with the 4.1.1
device driver which could shed some light on this problem?  We would
really like to get the DAT drive back on line, we have a lot of data on
DAT tapes and not being able to read them is problematic.