Re: Serial Port busy.

[Casper Dik <casper@holland>]

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>Once upon a time, a kindly hardware engineer explained this
>to me.  Because of the clock rates, what Sun boxes (up to an
>Ultra 2 at the time -- I don't know if it applies to boxes
>later than that) represent as 57600 is actually something in
>the ~52000 range.  This is because of a difference in clock
>rates.  Feel free to correct me if I'm wrong here.  So two
>Suns can talk to each other at "57600" and above, but you
>can't talk to another component that is actually talking at
>57600.  The best rate I was ever able to use was 38400.


This is true for all Sbus based systems; these have zs based
serial ports.

The later Ultra systems are PCI based and have a much better
serial chip (larger fifos, runs upto 400kbps).



(Ultra 5, 10, 30, 60, UE250, UE450 and the PCI I/O boards for
the UExx00 series)

If you want to check what type of system, try this:

ls -l /dev/term/a

New chips can be recognized by this:

New System (note "pci" for on-board PCI and "se" for the new Siemens
serial chip)

lrwxrwxrwx   1 root     root          47 May  6  1998 /dev/term/a -> ../../devices/pci@1f,4000/ebus@1/se@14,400000:a

Old system (obio, sbus; old zs based serial)

lrwxrwxrwx   1 root     root          32 Dec  6  1996 /dev/term/a -> ../../devices/obio/zs@0,100000:a


Casper
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