Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!know!zaphod.mps.ohio-state.edu!julius.cs.uiuc.edu!apple!voder!pyramid!lstowell
From: lstowell@pyrnova.pyramid.com (Lon Stowell)
Newsgroups: comp.dcom.lans
Subject: Re: Info req on IBM370 I/O channel
Keywords: IBM 370 channel network protocol
Message-ID: <129267@pyramid.pyramid.com>
Date: 4 Oct 90 19:54:12 GMT
Sender: daemon@pyramid.pyramid.com
Reply-To: lstowell@pyrnova.pyramid.com (Lon Stowell)
Organization: Pyramid Technology Corp., Mountain View, CA
Lines: 30

The IBM channel protocol is unfortunately NOT easily implemented
with "an 8-bit micro".   Attempting same is guaranteed to cause
Interface Control Checks!    There are some sequences which
require a MAXIMUM timing of less than 6 microseconds to execute
a fairly complicated series of tests and branches......

Most (channel secondary) interfaces use  Bit Slicers or other
RISC chips for signalling control....just for this reason.

The possibility of using a Channel Extender is quite
interesting....   These are boxes that come in two halves...

One sits at the mainframe and emulates a peripheral.....the
other sits at the remote site and provides emulation of the
IBM channel itself....    The two are connected over 56Kb to
T1/T3 serial lines and/or fiber optics.....

If you can find a vendor willing to let you eliminate the first
of the units (the one at the IBM host) and speak directly to the
T1 or fiber interface to the slave unit, you should be able to
drive an IBM peripheral......    This will NOT be a trivial
effort, but one actually wonders if anyone has actually done
this.....

Vendors of such channel extender boxes are Paradyne, of Key
Largo Florida,.....Network Systems of California (415 area
code..),,,,Storage Technologies in the Denver area......you may
also want to check with McData in the Colorado Denver suburbs.

Good luck.