Path: utzoo!attcan!uunet!lll-winken!uwm.edu!zaphod.mps.ohio-state.edu!tut.cis.ohio-state.edu!ucbvax!CORNELLC.CIT.CORNELL.EDU!K312240%AEARN
From: K312240%AEARN@CORNELLC.CIT.CORNELL.EDU (Klaus Kusche)
Newsgroups: comp.sys.transputer
Subject: Another Express problem....
Message-ID: <9003081453.AA25642@tcgould.TN.CORNELL.EDU>
Date: 8 Mar 90 16:02:59 GMT
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The Internet
Lines: 95
X-Unparsable-Date: Thu, 08 Mar 90 15:52:40 SET


Dear Mailing List:

Just another problem concerning Express:

We have the following hardware:

* A PC/386 compatible with one 100% B004-compatible transputer
  board. The board has a subsystem error/reset/analyze logic which
  behaves B004-compatible, *not* B008-compatible: Resetting the board
  itself is *not* propagated to the subsystem reset.

  I will call this transputer the root from now on.

* An external box containing 16 transputers and 4 C004 link switches.
  All the links go through the C004's, no hardwired connections. Root
  link 3 controls C004 configuration, root link 1 and 2 go to C004's,
  again no hardwired connections.

  All the reset signals of these transputers and all the reset signals
  of the C004 switches are wired together to a single reset line.
  This line (together with the combined analyze and error signals) is
  connected to the root's subsystem port.

  I will call these 16 transputers external transputers from now on.

Usually, I use this configuration as follows:

* I execute a program on the root which resets the subsystem and
  sets up the desired C004 connections.

  This leaves the root in a dirty state, the C004's in the desired
  topology, and the external transputers in a clean reset state.

* Then I boot the application normally.

  This resets and boots the root, but as the root reset is not
  propagated to the subsystem, the application will find a network
  of reset transputers in the desired link configuration.

* Before running the next program, I use my reset and reconfigure tool
  again.

This method has been tested and proven to work as desired.

With Express, the following happens:

* I run my configuration tool.

* I run the 'cnftool' with graphics and the automatic worm. It does
  find all 17 transputers, and it shows the correct link connections
  loaded into the C004's in the first step.

* I rerun my configuration tool, setting up exactly the same
  configuration again.

* I try to run 'exkload' to boot Express. It reports that it was able
  to find the root transputer, but that all links to the external
  transputers are unconnected.

* Obviously, when initializing the root transputer Express also
  issues a subsystem reset, which causes all the C004's to revert to
  their 'all links unconnected' state.

I tried all possible changes to the reset information in the Express
configuration description (by entering the configuration by hand in text
mode, by patching that file, etc.). I'm absolutely sure that this file
specifies 'down' type reset for all transputers (which should work), and
*never* specifies 'subsystem' reset, and the graphical reset tree
displayed by the 'cnftool' confirms that, but still, whenever I try
'exkload', the link switches are obviously reset for some damned reason.

Now my questions:

* Is my assumption correct that 'exkload' always issues a subsystem
  reset, even if the configuration file does not indicate a subsystem?

* Have I missed some tricky detail?

* What can be done against this nasty behaviour???

Many thanks in advance for your help!

************************************************************************
* Klaus Kusche                                                         *
* Research Institute for Symbolic Computation                          *
* Johannes Kepler University           Tel: +43 7236 3231 67           *
* A-4040 Linz                          Telex: (Austria) 22323 uni li a *
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*                                                                      *
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