QIC-40 driver writing

[Paul Allen]

I'm considering adding an inexpensive cartridge tape drive to my 386 Minix
system.  Since I'm not aware of anyone having done this before, I'm appealing to
the collective wisdom of the net.

Last July, in comp.os.minix article <Jul.4.22.07.42.1989.8770 at athos.rutgers.edu>,
Rick Thomas (rbthomas at athos.rutgers.edu) wrote:

>Incidentally, I did succeed in getting hold of the people who control
>the QIC-40 standard (Freeman Associates in Santa Barbara), and they
>sent me (free) the full set of literature on the standard.  The command
>protocol is really *gross*!  You send commands to the drive by sending
>a string of pulses over the "STEP" line (the one the floppys use to
>move the head from track to track) There are 30-odd different commands,
>so (assuming for the sake of argument that the Irwin drive is at least
>similar to QIC-40) one may have to send as many as 30 pulses, at
>intervals of 2.5 ms, and the timing between pulses is fairly critical,
>so the sending will probably have to be done in a tight cpu loop,
>possibly with interrupts prevented.  The drive responds by sending
>status info back over the TRACK-ZERO and INDEX lines.  That's up to
>75 ms with interrupts prevented.  What does that do to an RS232 line
>at 9600bps?!?  Still, It shouldn't be too hard to write a driver, if I
>could get full specs.  It just wouldn't be very good for concurrent use
>with communications activity.

I've requested the QIC-40 spec from Freeman Associates.  The price-leader
in the QIC-40 arena seems to be the CMS Jumbo at about $250.  When I 
called CMS, they wouldn't release any technical data.  The tech support
guy appologetically referred to a company policy from "upstairs" and
pointed me at Freeman Associates.

Given Rick's comments about timing above, does it make sense to try to
use a QIC-40 drive in a multiple-process environment?  Has anyone used
the QIC-40 spec to build a driver for Unix, or any other multitasking
OS?  I'd really like to be able to use the CMS drive, because the price
goes up by 2 to 4 times if I go to QIC-24.  :-(

If you have some insight to share, please use email and say which newsgroup
you saw this in.  If I get anything useful, I'll summarize to the appropriate
groups.

Thanks.

Paul Allen
pallen at atc.boeing.com
...!uw-beaver!bcsaic!pallen
-- 
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Paul L. Allen                       | pallen at atc.boeing.com
Boeing Advanced Technology Center   | ...!uw-beaver!bcsaic!pallen