exodus@mfgfoc.uucp (Greg Onufer) (12/30/88)
goodall@brillig.umd.edu (Sharon Goodall): > [[ ... For the rst device, 0 uses QIC-11 format and 8 > uses QIC-24. --wnl ]] Some Sun-2's can use QIC-24 and some cannot. It depends on the tape drive type and the tape controller. There is a Sun document on 1/4" tape drives that should be read by those who want to know more about the tapes and formats. It also describes which machines can use the two formats. The title is something like "A Tutorial on 1/4" Tape Drives". If I recall correctly, it also goes into care and feeding of the devices. It is not a technical paper-- it is oriented towards those who just need to know the basics. -greg -- Greg Onufer // Focus Semiconductor // University of the Pacific exodus@cheers.uucp (daver!cheers!exodus@Sun.COM) 415-965-0604
joey@tessi.uucp (Joe Pruett) (01/04/89)
You can send this to the list if you think it's useful. This info has been gleaned from various sources. I wish I could give credit, but I have no idea of who said what... There are two parameters to consider when dealing with quarter inch cartridge (QIC) tapes. One is number of tracks (4 or 9), the other is encoding format (QIC-11 or QIC-24). Older Sun-2's can only write 4-track QIC-11 tapes. Newer Sun-2's can only write 9-track QIC-11. And all Sun-3/4's can only write 9-track QIC-11 or 9-track QIC-24. As far as I know no-one writes 4-track QIC-24 tapes. The number of tracks is determined by the tape drive head. There is no way to write 4-track tapes with a 9-track drive (they're in the right position, but not wide enough to necessarily be readable by a 4-track drive). The QIC-11 versus QIC-24 format is determined by the controller and is software selectable if both formats are supported. QIC-11 has only 1 byte defined for block number, QIC-24 has 3 bytes. This means that QIC-11 has less overhead per block and is therefore higher density than QIC-24 (proven by experiment). I don't think that sun uses that block number, or that it ever will get used. I think it is supposed to be used for high-speed random positioning. Sun made a major boo-boo when they switched to QIC-24 for 4.0. Not only do they get less data per tape (maybe .5M less per 450 foot tape), they also had to update all those PROMS. All they needed to do was to switch to 9-track. If you look at some of the unbundled software for 4.0, you'll see that they now use QIC-11 with either 4-tracks or 9-tracks.
ZBERTJOE@DB0TUI6.BITNET (Joerg Schilling - H. Berthold AG Berlin) (01/24/89)
Hi,
the most importent difference between the QIC-11 (rst0) and the
QIC-24(rst8) format is that the tape controller places a burst at the very
beginning of the tape when the first data is recorded. This burst is
placed between the B.O.T. holes and the load point hole on the tape and
enables intelligent drives - as the Wangtek - to calibrate the position of
the Read/Write Head. This causes a Wangtek drive to use several seconds.
You can hear this - it moves the tape forwards and backwards until the
optimal head position for track 0 is found. Subsequent reads or writes
will use the so found position for track 0.
You should therefore use the QIC-24 format whenever possible to enhance
the interchangeability of the tapes. There will be less/no problems with
tapes comming from/going to drives with missaligned heads.
I think that is the real reason for SUN to change the format of their
installation tapes.
J. Schilling
H. Berthold AG
Teltowkanalstr. 1-4
D 1000 Berlin 46
+49 30 7795 - 400
joerg@berthold.de
.. tub!berthold!joerg
.. unido!berthold!joerg
.. sunmuc!berthold!joerg
.. sun!sunmuc!berthold!joerg