You're not my type [3270 terminal types and coax controller chips]]

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Louis Ohland

Nov 19, 2021, 12:21:25 PM11/19/21
So. Without the benefit of industrial plum brandy, I >think< there is a
slightly better understanding of the 3270 emulators.

Terminal types A and B. The functionality of the terminal is the type.

Coax controller chip, type A or B. B is the original, RG-62, 93 ohms.
Type A came out later, it added the ability to use 150 ohm STP -WITHOUT-
needing an external balun [so, it was gender-fluid, 93 -or- 150]

Nov 19, 2021, 4:59:42 PM11/19/21
On Fri, 19 Nov 2021 11:20:16 -0600, Louis Ohland <>
Using the proper balun they would all run on twisted pair. Our whole
office was on the IBM wiring system that used the big black "token
ring" jacks and you could plug in the appropriate balun/adapter for
3270 coax, TV/baseband coax, Ethernet, 4 wire Baseband or POTS
service. Obviously it also did T/R. We had a mix of stuff we used. I
was the only one using 4 wire baseband and Eduquest was using
Ethernet. Most were 3270 terminals.
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