TK70 tape drive media?

Pete Turnbull pete at
Sat Jan 28 18:52:54 CST 2006

On Jan 27 2006, 18:28, Zane H. Healy wrote:
> At 5:53 PM -0700 1/27/06, Richard wrote:
> >In article <a06200707c000674f8182@[]>,
> >     "Zane H. Healy" <healyzh at>  writes:
> >
> >>  At 12:00 PM -0700 1/27/06, Richard wrote:
> >>  >Well, if I am going to get the latest OpenVMS hobbyist edition,
> >>  >need to hook a SCSI CD-ROM drive up to it.  I think I have one
on the
> >>  >shelf somewhere.
> >>
> >>  It needs to be more than just a SCSI CD-ROM, it must support
> >>512-byte blocks.
> >
> >How can I tell?  Its Toshiba SCSI CD-ROM model TXM3401E1
> *GOOD* question.  I don't see any actual indication.  However, after
> some Googling, I found this page, since this
> person is using one on his SGI Indigo, I'd say you're in luck.

SGIs have similar problems to Suns, Vaxen, and several other machines,
in needing drives that support 512-byte blocks.  That's not quite the
whole story, though.  Some CD-ROM drives support a software command to
switch to 512-byte blocks.  Some machines can issue that command: later
SGIs such as Indys do, Indigos don't (at least, the PROM doesn't; IRIX

Toshiba XM3201, 3301, and 3401 have a set of pads that can be used to
set the blocksize, and most of these drives don't support the software
command.  The XM3601, XM54xx and later do support the software command,
and don't use the pads.

For the 3401 and its mates, you need to look for two pairs of half-moon
pads on the top side of the circit board, towards the right rear.  The
halves in each pair will normally be shorted together with a thin
copper trace on the board, for standard 2048-byte blocks.  They're
often labelled "0" and "1".  Leaving "0" shorted but opening "1" gives
512-byte blocks.  "0" open and "1" shorted is what SGIs use for
bootable drives.  Suns and Intergraph machines have both open.  All the
settings except the factory default gives 512-byte blocks.

The following is from an old SGI hardware FAQ:

                                                 |power   SCSI    |
  '0'   '1'  O=CUT/OPEN S=SHORTED/SOLDERED       |              01|
  ----------                                     |----------------|
   S     S   Toshiba Default (2048 byte block)   |                |
   S     O   512 byte blocks                     |     TOP        |
   O     S   SGI ( Bootable )                    |     OF         |
   O     O   Sun / Integraph                     |     DRIVE      |
                                                 |                |
                                                 |                |
                                                 |                |

Pete						Peter Turnbull
						Network Manager
						University of York

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