Re: USB, 1394, PCI, ISA, IDE ??

[Jon Elson <jmelson-at-artsci.wustl.edu>]

Dave Schecter wrote:

> So here we are looking for a cheap easy way to get on the Bus.
> How about IDE ?  Or SCSI ?

A small burp on the IDE bus will trsh your disk, if the machine
has an IDE disk.  I know, the hard way!  I have an IDE flash-card
adaptor.  This has a little green led, and an ejector button.  I had
no idea you were never supposed to eject a flash card while the
machine was powered on.  The flash card reader was even connected
to the OTHER IDE port from the disk drive.  It made a mess all over
Windows DLL files, and I had quite a time recovering my user files
and reinstalling Windows over the damaged system.

So, I would strongly advise not to try to put together something like
this on the IDE.  The SCSI protocol is quite complex, and if you
had a disk drive on it, it could cause unexpected latency problems
for the real-time data transfers.  SCSI works best when sending
large blocks of data back and forth, not small blocks of a couple
of words, at a very high request rate.

If the USB protocol and drivers can be made real-time compliant,
that might be a very good solution, as it won't be carrying
disk or other system transfers.

Jon