Are old SCSI tape drives not all created equal?

[Chuck Guzis]

On 08/19/2016 09:24 AM, js at cimmeri.com wrote:

> Where might I find information on how to form SCSI command data
> blocks so as to try the above commands?   I sent just an "01" to the
> TEAC MT-2ST, and it did rewind.. but did not react to any of the
> other above commands just by sending single bytes.
> 
> Oddly, the OnStream drive did *not* accept an 01 command.
> 
> Thank you- -John

John, what's your working OS platform?  For fooling with SCSI, the ASPI
interface of MS-DOS is pretty straightforward--and easy to use.

http://ftp.isu.edu.tw/pub/Hardware/ADAPTEC/adaptec/aspi_dos.txt

..and if you goof up, just hit the RESET button and you're back in
business in a few seconds.

A CDB's a CDB, so whatever you learn on DOS can easily be transfered to
other OS interfaces (SPTI, SG, CAM, etc.).

As far as tape-drive specific commands, there's always an ANSI T10
document, but that's like trying to learn about parking regulations from
a university law library--it's probably all there, but you'll have to
plow your way through a lot of stuff.  FWIW, T10 doesn't refer to the
things as "tape drives", but "sequential access devices".  Here's a T10
draft:

http://hackipedia.org/Hardware/SCSI/Stream%20Commands/SCSI-3%20Stream%20Commands.pdf

By far and away, the best place to learn practical SCSI interfacing is
from vendor's manuals themselves.  One I found particularly useful was
the HP 35470 DDS drive OEM product manual.  Very clear writing style.

Bitsavers is full of product manuals detailing exactly what and how a
product supports.

--Chuck