gallow@batcomputer.tn.cornell.edu (Steven Gallow) (02/08/89)
A while back there was a discussion on 9 track tape drives for the
IBM RT. I have called CFN Industries (Livermore California) for
information on their drives. I'm interested in getting quotes from
some other companies. The drive has to be at least 1600/6250 BPI.
Does anyone have any information?
Thanks in Advance
Steve Gallowbuck@siswat.UUCP (A. Lester Buck) (02/13/89)
In article <7348@batcomputer.tn.cornell.edu>, gallow@batcomputer.tn.cornell.edu (Steven Gallow) writes: > > A while back there was a discussion on 9 track tape drives for the > IBM RT. I have called CFN Industries (Livermore California) for > information on their drives. I'm interested in getting quotes from > some other companies. The drive has to be at least 1600/6250 BPI. > Does anyone have any information? > > Thanks in Advance > Steve Gallow I am doing some contract work on a tape driver for the RT. My client has the tape drive on the SCSI bus, which requires the IBM SCSI adapter at ~$1100 and only supports differential SCSI interfaces, which are somewhat rare. I guess you could use any old AT interface card if you wanted a direct path, but we are using AIX and you would need your own VRM driver, which is a pain to write and debug. If you use the SCSI VRM driver IBM supplies, you only need to fight with it for a couple of weeks. Of course, if you need to write odd length records, you are out of luck, since VRM gags on most transfers that are not multiples of four bytes. And if you need to do a SCSI operation other than READ or WRITE that moves more than 6K of data, you get to write your own VRM driver, because the IBM driver doesn't support it. We are evaluating a Cipher M990 GCR CacheTape, with models from HP and StorageTek to be tested soon. The Cipher was actually purchased from a Dickens Data near Atlanta, but the only reason they can charge almost double the base price of the drive is that they supplied a (sorta) working AIX driver. Sorta means that until the latest revision, asking for say 32K bytes with 10K physical records would give you 32K of data in your buffer, the driver merrrily spanning records for you and hiding all details of blocking. Limited ioctl() support for tape movement, too. If anyone is starting to write a tape driver for AIX, note that the manual for the SCSI VRM driver is wrong in the bit positions for setting variable byte transfers: it says bits 2 & 3, but it should be bits 1 & 2 (from a helpful guy in Austin who was reading the source as we talked). Amazing how well things worked after that! If anyone is considering starting from scratch with SCSI on the RT, they might look at the Adaptec 1542 host adapter. It supports single-ended devices (which are much more common) with burst mode from the host adapter to the RT memory of up to 10MBytes/sec. Very clean design with mailboxes. And a Mr. Christer Bernerus at uunet!mcvax!utc.chalmers.se!bernerus has written drivers for tape and disk under AOS4.3, so we know the hardware works. A VRM driver would be some extra work, though. -- A. Lester Buck ...!texbell!moray!siswat!buck