Tape Backups for SV/AT

[J.R. Stoner]

>From article <433 at dragos.UUCP>, by ruiu at dragos.UUCP (Dragos Ruiu):
,    Does anyone have anything approaching drivers for a tape backup that
, uses the second floppy drive as an interface?
 
 [...]

,   It strikes me that a driver that talks to a tape drive that looks like a
, floppy should be easy. Can anyone help me ?

I can't help you on specifics, but I can tell you from long and sad
experience a floppy-tape is not an easy task.  How do I know?  I wrote the
TIP program for CompuPro tape backup using IRWIN 110 drives two years ago.
The hardest thing was the host software had to do any error management
and random access positioning of the DC1000 tape.  The hardest thing was the
gotchas when you had to be two blocks in front of the desired block and then
you can accelerate and be up to speed by the time you reach your block.
Also, the tape system required me to shut down *everything*.  The Concurrent
BDOS, floppy disk interrupts, hard disk interrupts, and most catastrophic:
the network server interrupt.  We couldn't have those nast 377.2 ms
reconfiguration interrupts happen while I am trying to zoot data at non-dma
rates now, or I might just have to stop the streamer and backup about 4
blocks and reposition and attempt to restart that block.

Needless to say, TIP wound up as a program whose listing is a stack of paper
6" high.  It is not a pretty sight.  Thank goodness we buy MCD-40's now.
I don't ever want to write another IRWIN driver.

, Dragos Ruiu  ruiu at dragos.UUCP    "We will probably never announce a processor
,     ...alberta!dragos!ruiu    as a RISC processor."-Ken Olsen   ...wanna bet?