Re: RS232 then and now - cctalk

3 Feb 2025

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 Message: 26
Date: Sat, 1 Feb 2025 18:13:17 -0500
From: Nigel Johnson Ham &lt;g4ajq1(a)gmail.com&gt;
Subject: [cctalk] Re: RS232 then and now

On 2025-02-01 18:11, Chuck Guzis via cctalk wrote:
  One mystery to me was why did the industry stick
with the EIA-232 levels
 for terminals and whatnot long after differential EIA-422 was
 introduced.  Higher-speed, better noise immunity, single-ended power
 supply...  Seems that the popular places were Appletalk and ST506 data
 lines.  But not on DTE/DCE.   If you were using full-voltage (±15-±25)
 at high speeds (>500Kbps), the slew rates were ridiculous.

 Inertia?  My old 80286 motherboard had junper-selectable 232 or 422.

 Still have a couple of tubes of 422 drivers/receivers.

 --Chuck
 DEC had RS422 available on their DLJ11J four-port interface, but I never
saw it used in the field.

The Otrona Attache has two serial ports, DA-15 female, that are jumper selectable between
RS-232C, RS-422 or RS-423.

Bob