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.
--
Nigel Johnson, MSc., MIEEE, MCSE VE3ID/G4AJQ/VA3MCU
Amateur Radio, the origin of the open-source concept!
Skype: TILBURY2591
