Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!know!zaphod.mps.ohio-state.edu!sdd.hp.com!hp-pcd!hpfcso!rjn
From: rjn@hpfcso.HP.COM (Bob Niland)
Newsgroups: comp.sys.hp
Subject: Re: Serial Port for Series 400 -- Fast Baud Rate ?
Message-ID: <7370230@hpfcso.HP.COM>
Date: 9 Oct 90 18:12:35 GMT
References: <587@dptechno.UUCP>
Organization: Hewlett-Packard/FSY Ft.Collins,CO,USA
Lines: 42

re: > Does anyone know if the serial port on the new series 400 computers
    > from hp (says HP and apollo on the lable) supports fast baud rates?

Yes.  It can be set to rates up to 460K bps.  Note:  On Series 400, this is
for port 1 only.  Ports 2&3 (available via K2292 fan-out cable) max out at
19.2K, have single-byte buffering and only software flow control.

> I would like to run a trailblazer modem at 19.2K for uucp transfers.
> Using the 9000/300 series fast baud rates could not be sustained in uucp
> due to a 1 character hardware buffer.

The 345/375/400 have a 16-byte FIFO, which helps.

> Anyway, if the new 400 series has better serial port hardware, is
> it supported in 7.03 unix ? 

Not officially (it's in 7.05).  You can obtain an unsupported patch kit by
having your local HP support representative contact me.  This shar package
also includes centronics patches and tips.

> Also, has anyone actually tried uucp at 19.2K on these machines ?

I am writing this note over a 19.2K link using HST modems.  One end is a 375
using the internal port with 7.05 features turned on.  Although it works for
ordinary 'cu', it is not 100% reliable for file transfers.  ~%put has a 1%
error rate, and long uucp (f protocol) transfers often fail.  I suspect that
this is due to the 16-byte FIFO being smaller than the 32-byte hysteresis
normally used for Xon/Xoff flow control.  I will be switching back to a mux
port shortly.

My guess is that the FIFO would provide reliable 9600 bps operation, which
is an improvement over the 2400 or so we see on the old 1-byte ports.

The new ports also have CTS/RTS bidirectional hardware flow control.  If you
can use this in your application, and the external device sends less than 16
bytes after detecting RTS high, I would expect very reliable operation and
high speeds.

Regards,                                              Hewlett-Packard
Bob Niland                                            3404 East Harmony Road
Internet: rjn@hpfcrjn.FC.HP.COM                       Fort Collins
UUCP: [hplabs|hpu*!hpfcse]!hpfcrjn!rjn                CO          80525-9599