Path: utzoo!attcan!uunet!lll-winken!lll-tis!helios.ee.lbl.gov!pasteur!ucbvax!ucsd!ucsdhub!hp-sdd!hplabs!hpda!hpcupt1!hpisoa1!vandys
From: vandys@hpisoa1.HP.COM (Andrew Valencia)
Newsgroups: comp.unix.microport
Subject: Re: Need INFO about possibilities of IBM Mainframe connection
Message-ID: <11190009@hpisoa1.HP.COM>
Date: 5 Aug 88 15:57:53 GMT
References: <674@mssx.UUCP>
Organization: Hewlett Packard, Cupertino
Lines: 19

/ hpisoa1:comp.unix.microport / mejia@laidbak.UUCP (Galo Mejia) /  9:27 pm  Jul 29, 1988 /
>I would guess, however, that a coax_card is need. 3270 is a family of IBM
>terminals that connect to a terminal cluster  (models 3274, 3276) through a
>coax_cable (they use BYSYNC protocol to talk to their communications control
>program. ei. VTAM) There are many coax cards in the market (IRMA, AST, ITT and
>others, used to be around $500) I used in 286 machines, so I don't know about
>386.

    Part of the story.  A 3274/3278 cluster may be connected via coax,
bisync/RS-232, or SDLC/RS-232.  A console for a mainframe is also coax
attached, but it's a different protocol from the 3274/3278 coax attach.
Last I looked (quite a while ago), SCO only supported the RS-232 connection.
The coax connection was designed for a dedicated device--as I recollect,
there was a very real danger of using up your whole system just trying to
be a terminal.  The coax protocols and connection are also much more complex
than the SDLC or Bisync ones.  For speed however, there's no comparison--
the coax attach is incredible.  I'd take one for my UN*X system connection
any day of the week!

					Andy