IBM 3270 coaxial type A protocol controller chip

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Louis Ohland

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Nov 19, 2021, 10:59:04 AM11/19/21
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So. I'm not findting a mountain of documentation, here. What is the
difference between the "A" and "B" Coax controller chips?

Does this have anything to do with the 3270 /A and 3270 /B versions? Is
Elvis still alive? Was Joe Biden the man on the grassy knoll?

Louis Ohland

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Nov 19, 2021, 11:08:07 AM11/19/21
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Uh, the original 3270 used a 93 ohm, RG-62 coax [close fit to ECL].
Later versions could use the 150 ohm [ICS?] as well.

I think...

Louis Ohland

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Nov 19, 2021, 11:09:27 AM11/19/21
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https://www.rs-online.com/designspark/a-fresh-look-at-ibm-3270-information-display-system

The physical interface of choice for a regular terminal is RS-232 and
the standard specifies 15m as the maximum cable length, with a typical
speed of 9,600 bits/second. Whereas a 3270 terminal has a 93 ohm coax
connection and can be located up to 3 kilometres from its controller,
with a data link that operates at 2.3587 Mb/s.
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