km@emory.uucp (Ken Mandelberg) (05/17/88)
There are several companies which make 40 Meg streaming tape drives
with a form factor and interface compatible with a 5.25 inch floppy
disk. They are meant for an IBM PC and are meant to use the existing
floppy controller. A device driver for the PC is provided.
Does anyone know the details of how these things really work? What does
the tape drive do when the controller pulses the drive line that is
meant to move the floppy head in a track? In general, how do the floppy
actions map into tape actions?
What I'm really wondering is how to use one of these to replace a
floppy on a Unix machine (the 3B1 particularly). I'm wondering if its
possible to just plug in the tape instead of the floppy and use a
sequence of read/write/lseek on the "floppy" device file to manipulate
the tape.
If it helps the 3B1 uses a WD2797 to control the floppy.
I called "Archive" a maker of such drives for technical information.
The tech support person I talked to really couldn't tell me how it
worked or provide a theory of operation documentation. All he really
seemed able to be able to address was issues in installing the drive in
an IBM PC. I susppose that is what his job is.
--
Ken Mandelberg | {decvax,sun!sunatl,gatech}!emory!km UUCP
Emory University | km@emory BITNET
Dept of Math and CS | km@emory.ARPA ARPA,CSNET
Atlanta, GA 30322 | Phone: (404) 727-7963ward@cfa.harvard.EDU (Steve Ward) (05/18/88)
In article <2922@emory.uucp>, km@emory.uucp (Ken Mandelberg) writes: > There are several companies which make 40 Meg streaming tape drives > with a form factor and interface compatible with a 5.25 inch floppy > disk. They are meant for an IBM PC and are meant to use the existing > floppy controller. A device driver for the PC is provided. > > What I'm really wondering is how to use one of these to replace a > floppy on a Unix machine (the 3B1 particularly). I'm wondering if its > possible to just plug in the tape instead of the floppy and use a > sequence of read/write/lseek on the "floppy" device file to manipulate > the tape. You cannot just swap the tape drive in place of the floppy drive. There are several versions of floppy I/O tape drives, and maybe someone makes one that truly emulates a floppy disk drive, but I am unaware of any. typically the minimum data block size (sector) is much larger than 512 bytes and the number of floppy "tracks" and "sectors/track" varies considerably from a real floppy disk drive. This means that at a minimum you need a unique device driver or tape utility program to use these tape drives. Some of them conform to the QIC-40 specification. These will allow exchange of data cartridges (assuming complete compliance to QIC-40) among different vendor QIC-40 tape drives. This multi-vendor interchange capability does not exist among non-QIC-40 tape drives, even though they may use the same DC2000 (or whatever) digital tape cartridge. For this reason you are better off using the QIC-40 tape drive. Still, you are faced with writing a device driver and/or a tape drive utility program. The drives offered for the PC come with the necessary software. For use with non-PC computers you will have to write your own. If you are interested in interfacing and using QIC-40 tape drives for backup on small workstation computers (PC's, Unix boxes, MicroVAXen, etc) then please send me your name, e-mail and postal mail addresses and phone number. A second use of these tape drives is as a data interchange medium. The QIC-40 standard assures exchange because it also defines the data storage (incl. hierarchical file naming) format. I am looking into this and would be willing to send out updates to an informal mail list. Indicate whether you might be willing to help write software. I might be able to supply hardware for development/test purposes to a couple of people. BTW, these QIC-40 drives are available with floppy disk I/O as noted, and also with SCSI I/O as well. There is a big gap in cost, convenience, and storage capacity for data interchange among computers between the lowly floppy and nine-track tape, the only two near-universal exchange media. QIC-40 may prove to be a near-floppy cost, 40MB capacity near-universal data interchange medium. Steven M. Ward Harvard-Smithsonian Observatory 60 Garden Street, M/S 25 Cambridge, MA 02138 (617)495-7201 ward@cfa.harvard.edu {ihnp4,seismo}!harvard!cfa!ward >