In message <x7el0wopkg.fsf@capsicum.wsrcc.com>, Wolfgang S. Rupprecht writes:
>
>smb@research.att.com (Steven M. Bellovin) writes:
>> I've run RS-232 lines for at least 100 meters, and probably 150.  Mind 
>> you, this was back when 19.2 Kbps was fast, but...  Use high-quality 
>> cable; the limiting factor is generally the capacitance of the line, 
>> which tends to smear the pulses.  And don't be surprised if you can't 
>> run at 230 Kbps.
>
>Wow, I guess cables and driver technology has gotten better.  Back
>when vt-100's ruled the world there was a crazy communications company
>in Cambridge, Mass that had a farm of 10-bit/byte unix boxes located a
>few buildings from the engineering lab.  We engineers were stuck using
>serial cables that ran the length of 3 buildings; it was only with the
>aid of rs-232 to current loop converters at both ends that the damn
>things ran at all.  They worked somewhat reliably at 9600 bits/sec and
>if you got really lucky and the planets were in conjunction you could
>sometimes get 19200 bits/sec to work.  The lines that sometimes worked
>at 19.2k were highly coveted for eprom download lines.

Must have been the luck of the draw -- I'm talking about early 1980s,
which is hardly reent.

		--Steve Bellovin, http://www.research.att.com/~smb (me)
		http://www.wilyhacker.com (2nd edition of "Firewalls" book)