Re: [Spock@SAMSON.cadr.dialnet.symbolics.com: IFU]

[Spock <Spock@samson.cadr.dialnet.symbolics.com>]

Snail Mail Address: American Microsystems Inc. (A wholly owned
		    subsidiary of Gould Inc.) CAD Research Lab. P.O.
		    Box 967 Twain Harte, CA  95383
Phone Number:       (209)586-7422

    Date: Thu, 1 Dec 88 13:51 PST
    From: Mabry Tyson <TYSON@AI.SRI.COM>

    Yes, there are problems in the IFU.  We have probably 25 or so IFU
    machines.  *Most* of them work fine most of the time.  We've had a
    couple of problematic machines.  For some reason, the problems like you
    described appear to occur on particular machines (even with different board
    sets).  My particular machine was plagued by the RPLACD errors.  They seemed
    to come in bunches.  Another machine here was plagued with CALL-1 errors.

    At least some people within Symbolics know there are problems.  I seriously
    doubt that anything will be done about it (I don't like it, but that may
    just be life).  It's sorta like the decision not to put an Ivory card out
    to fit in the L-Bus machines.  Not enough manpower nor enough market.

This is alright with me as long as there are viable alternatives.

    Here is some code that I wrote to *try* to catch and prevent the CALL-1 errors.
    This code should be considered somewhat untrusted as I've never seen it
    correct the error.  However, the machine it was put into was getting the errors
    almost daily but it has been running with this code for about 2 weeks without
    having the error occur.   Notice that it tries to fix both a CALL-1 error and
    an error on +.  I haven't had the RPLACD problem since I wrote this code so
    I haven't tried to incorporate it.   Maybe you can...  (This code is based on
    an idea from someone inside Symbolics (who had his own code but flushed it
    before I asked for it) but all coding mistakes are my own.)

    And, yes, it usually does help to replace the IFU.  But you may get the problem
    back eventually.


Thanks for the code.  I will probably use it as a band-aid until I can
get my MC board back.  I like the performance boost of the IFU but it
doesn't seem worth it to me.  I can't use the machine for long
unattended runs (which I need to do a *lot*) because it always seems to
bomb out *right* after I leave and 9 times out of 10 it's the IFU
problem.  I'm not too fond of software fixes for hardware problems, but
I *sure* *appreciate* your help and I can put your code to good use.
Thanks again.