3rd party tape drives and "tc" driver
Rick Auricchio
rick at Apple.COM
Sat Mar 17 04:00:03 AEST 1990
Well, here's my two cents. (I often skim this newsgroup but virtually never
find anything interesting, or that I'm qualified to answer.)
Y'all can give me the credit/blame for the tc driver. Yes, the Apple drive
is a "stringy disk", so the driver does oddball stuff to make it *look* like
a straight 9-track device, which un*x is generally used to handling. This
includes simulated filemarks.
The source for the driver is available in Apple's "Driver Kit" or whatever
it's really called. As far as I know, it's available to developers thru the
direct support channels (and maybe thru APDA, which is an Apple department
that distributes this kinda stuff). I don't know the legal issues on
redistribution, but I *think* third parties are allowed to hack the sample
driver(s) and do what they want. But don't quote me on this.
Also included in the kit is a portion of kernel source (especially all the
I/O stuff), and a bunch of binary files (the stuff owned by AT&T). Of course,
you can't hack "built-in" kernel drivers and redistribute a new *kernel*,
because AT&T won't like that. But you can distribute *configurable* drivers.
Okay, now back to tc. How can I say this with relative safety? We're not
allowed to comment on unannounced products.
Hypothetically speaking, mind you, I might have added some model-dependent
tables and routines to tc to allow somewhat easy addition of new drive types.
All hypothetical, of course. I wouldn't want to leak any info.
As for supporting an Archive drive, here are a few ideas/opinions. I'd make it
require an 8K-byte blocking factor from the user, exactly like the Apple
drive, for user convenience. Avoid confusion about blocksizes and such, and
make it work identically (except for speed/capacity). Besides, an Archive
won't stream if you try to write smaller than 4K anyway. I'd add the ioctl
for retensioning, just for completeness. And I'd fix a couple of bugs in the
existing tc driver along the way.
Cheers!
--
--
Rick Auricchio, Apple Computer Inc, 20525 Mariani Av MS 58A Cupertino CA 95014
sun!apple!rick OR rick at apple.COM Mooney N894AR (408) 974-4227
Never eat prunes when you're famished.
My opinion is my own. My employer? They use a windsock and a fire extinguisher.
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