[SunHELP] IPX scsi cdrom [not] playing ball

[sunhelp at sunhelp.org]

I have scoured faq's, sun-docs and every other source I can think of, so 
please
help me - before I run screaming into the wide blue yonder.....

I have a Sun SPARCStation IPX (64Mb RAM, 450Mb HD etc; etc.)
It has an external SCSI Tape and CD-ROM, both Sun badged.
All worked 100% under SunOS 4. I installed RedHat Linux 6.2.
All worked 100% under Linux.
[ Dammit - it used to bloody automount data disks! :-D ]

The IPX's NVRAM battery gave up at approx 10 years, as expected.
A new NVRAM was fitted and the network settings were correctly
re-set as in the NVRAM FAQ, and retained after switching off.

But..... the CD-ROM is no longer recognised, neither can I boot
from the internal HD automatically, I have to  at the ok prompt.

ALL SCSI devices are picked up "correctly" during the boot, and
<probe-scsi> confirms that they are all recognised OK.

<devalias> shows the CDROM as.....
    /sbus/esp at 0/800000/sd at 6,0:c
.....which implies:-
/sbus = unique sbus  (really /sbus at 1,f8000000)
/esp = sbus slot 0, offset 800000
/sd = scsi target 6, logical unit number 0


When the CDROM is physically disconnected from the scsi port,
and the system re-booted, no CD ROM is detected. The request
to boot cdrom at the ok prompt is met with.....
    Boot device /sbus/esp at 0/800000/sd at 6,0:c File and args:
    SCSI device 6,0 is not responding
    Can't open boot device
.....and we are returned to the ok prompt.

When the CDROM IS physically connected to the scsi port,
and the system re-booted, the CD ROM is detected. The request
to boot cdrom at the ok prompt is met with.....
    Boot device /sbus/esp at 0/800000/sd at 6,0:c File and args:
.....and the system freezes.

All leads and connections are good, at least for the eternal
SCSI tape unit, which works 100% correctly regardless of where
in the SCSI chain it is connected - before or after the CD-ROM.

The data CD's are valid - readable correctly on other workstations.

Booting from the HD into Linux proceeds without further errors.
On inserting a CD, the unit activates and reads the CD.
Running CD-ROM audio player works 100% correctly, track info is
read OK and the audio can be heard on the headphones. Software
eject commands also work correctly.
Attempting to read a data disk fails comprehensively. The following
may provide some clues.....

The following comes up during the boot-up process.
The [XXX] are my marks against relevant lines.....
--------------------------------------------------------------
    VFS: Diskquotas version dquot_6.4.0 initialized
    POSIX conformance testing by UNIFIX
    sbus0: Clock 20.0 MHz
    dma0: Revision 1 PLUS
    RAM disk driver initialized:  16 RAM disks of 4096K size
    Floppy drive(s): fd0 is 1.44M
    FDC 0 is a pre-1991 82077
    md driver 0.90.0 MAX_MD_DEVS=256, MAX_REAL=12
    esp0: IRQ 3 SCSI ID 7 Clk 20MHz CCF=4 TOut 167 NCR53C90A(esp100a)
    ESP: Total of 1 ESP hosts found, 1 actually in use.
    scsi0 : Sparc ESP100A (NCR53C90A)
    scsi : 1 host.
      Vendor: SEAGATE   Model: ST1480   SUN0424  Rev: 6266
      Type:   Direct-Access                      ANSI SCSI revision: 02
    Detected scsi disk sda at scsi0, channel 0, id 3, lun 0
      Vendor: EXABYTE   Model: EXB-8200          Rev: 263H
      Type:   Sequential-Access                  ANSI SCSI revision: 01
[XXX]     Vendor: SONY      Model: CD-ROM CDU-8012   Rev: 3.1d
[XXX]     Type:   CD-ROM                             ANSI SCSI revision: 02
[XXX]   Detected scsi CD-ROM sr0 at scsi0, channel 0, id 6, lun 0
[XXX]   scsi : detected 1 SCSI cdrom 1 SCSI disk total.
[XXX]   Uniform CDROM driver Revision: 2.56
    esp0: target 3 [period 200ns offset 15 5.00MHz synchronous SCSI]
    SCSI device sda: hdwr sector= 512 bytes. Sectors= 843284 [411 MB] [0.4 GB]
    sunlance.c:v1.12 11/Mar/99 Miguel de Icaza (miguel at nuclecu.unam.mx)
    eth0: LANCE 08:00:20:0b:d9:ac
    Partition check:
     sda: sda1 sda2 sda3 sda4
    md.c: sizeof(mdp_super_t) = 4104
    autodetecting RAID arrays
    autorun ...
    ... autorun DONE.
    VFS: Mounted root (ext2 filesystem) readonly.
    Adding Swap: 65872k swap-space (priority -1)
    amd7930 at 0xfe00d000 irq 13
    st: bufsize 32768, wrt 30720, max buffers 4, s/g segs 16.
    Detected scsi tape st0 at scsi0, channel 0, id 5, lun 0
    device eth0 entered promiscuous mode
    sunmouse: Successfully adjusted to 1200 baud.
--------------------------------------------------------------
The 3rd [XXX] line suggest that sr0 may be the CD-ROM "device" ????

In /dev there are st? devices, and st0 is the tape unit.
Cat /dev/st0 activates the tape unit and starts "trying" to read it.
Cat /dev/st0 without a tape in says /dev/st0: Input/output error
Cat /dev/st1 says "device not configured". [ Not surprisingly :-) ]

In /dev there are scd? Devices.
Cat /dev/scd0 says "no medium found".
Cat /dev/scd1 says "no such device". [ Which there isn't ]
The implication is that /dev/sdc0 IS configured/loaded [ I think ]

In /dev there are NO devices called sr?, nor in /dev/MAKEDEV

There is, in /dev, /dev/cdrom linked to /dev/scd0
Attempting to mount either fails - no media found.
Attempting to read either directly with dd if=/dev/???? of=/dev/null
where ???? is cdrom, scd0 OR sr0 produces an error as follows.....
    sr0:CDROM not ready. Make sure there is a disk in the drive
    CDROM:open failed
    VFS:disk change detected in device sr(11,0)
Using the same dd command on /dev/st0 activates the tape, on the
same SCSI link as the CDROM, and starts to read it.

I am missing something obvious, simple and self-evident.
What????
N!k