EIA 232 vs. 422, Color Computers (was Re: Serial floppy drives)

From: Dwight K. Elvey <dwightk.elvey_at_amd.com>
Date: Thu Sep 5 18:07:00 2002

>From: "Fred Cisin (XenoSoft)" <cisin_at_xenosoft.com>
>
>> > similar. 422 by the way is specified to go almost 1000 feet, while with
232
>> > you are lucky to get over 10 feet. Regards - Mike
>
>On Thu, 5 Sep 2002, Sellam Ismail wrote:
>> That's not true. Serial cable can go for a good many feet before the
>> signal breaks down (someone should pipe in with actual data ;)
>
>It'll handle way more than its spec calls for. When researching the
>content for "RS232 Solution", Joe Campbell ran it through a couple of
>thousand feet of wire (on a spool). Well, I guess that by being on a
>spool, the two ends were less than 10 feet apart. :-)
>
>
>The original IBM PC Parallel Printer Port was the one that was spec'ed at
>10 feet (3 meters). I often ran 30 feet with it.
>I have no idea what the spec is for 1284.
>
>

Hi Fred
 Did he stretch the spools out and put a 5 PH blower that
cycles on and off in each machine at the ends. I think
not! There is a big difference between running a signal
through a spool ( effective length for noise being vary
short ) and running in a low noise environment as compared
to many real world environments. In the spool, he was only
looking at resistive loss and not any of the other factors.
 On your PC example, it was intended to run in a low noise
environment. If it failed to work, IBM would simple shrug
and say 'You are only suppose to run it with a nice PC
and nothing else. It was never intended to be used like
that.' Besides, the parallel port is suppose to be a
terminated signal and not subject to issues of under
driven, as in the case of RS-232.
Dwight
Received on Thu Sep 05 2002 - 18:07:00 BST