[comp.lsi.cad] Resistance extraction bug in magic v.6

ge@mcnc.org (George Entenman) (12/15/90)

We seem to have found a small bug in the magic version 6.0
resistance extraction.  In the technology file the contact
resistance is set using the command:

	contact type size R

The documentation indicates that type is the type of contact,
size is the length of a minimum contact, and R is the
resistance of a single contact in milliohms.  We entered this
information for our technology and tried a few simple
examples.  The results were not correct and the problem was
traced to the contact resistance.  After poking through the
Magic 6 resistance code we found that in the file ResMakeRes.c
that the resistance of a contact was computed as follows

	(area of the contact)/size

instead of

	(area of the contact)/size*size

The code would work if the definition of "size" was changed to
be the area of a minimum contact instead of the length of one
side.  The best thing to do is probably to change the code
since a documentation change depends on the user noticing the
change instead of the installer making an update.  Who, if
anyone is responsible for accumulating and distributing bug
fixes for magic version 6.0?

				Fred Heaton and George Entenman

upton@ole.UUCP (Mike Upton) (12/16/90)

It may not be a bug, the resistance of a contact often varies with the
perimiter of the contact, not the area. This is due to the thinning 
of the metal as it crosses the step down into the contact.

Mike Upton

mayo@wrl.dec.com (Bob Mayo) (12/20/90)

In article <2743@speedy.mcnc.org> ge@mcnc.org (George Entenman) writes:
>Who, if anyone is responsible for accumulating and distributing bug
>fixes for magic version 6.0?

I accumulate and distribute them.  I have a very limited amount of time to
spend actually tracking bugs down, but am happy to collect and distribute
the reports and fixes sent by others.

There is a collection of files available for FTP as follows:
        machine:    gatekeeper.dec.com  (16.1.0.2)
        account:    anonymous
        password:   guest
        directory:  pub/DEC/magic

Send mail to me if you don't have FTP access.  The first file to look at
is called "index".  The contents of index are about to be updated, and here's 
what it will look like in a day or so:

-------------------------------------------------------------------------------
Magic Note #1 - 9/14/90 - Magic V6 is ready (a copy of the announcement)
Magic Note #2 - 9/19/90 - Documentation changes (fixed in releases after 9/20/90)
Magic Note #3 - 9/19/90 - Mode problem on graphics files (fixed in releases after 9/20
Magic Note #4 - 9/19/90 - rindex macro for new HPUX releases (7.0 and later)
Magic Note #5 - 9/19/90 - compiling magic using "gcc", one user's experience
Magic Note #6 - 9/19/90 - Public FTP area for Magic notes
Magic Note #7 - 9/20/90 - Compiling rsim, one user's suggestions & hints
Magic Note #8 - 9/26/90 - Magic tries to open bogus directories
Magic Note #9 - 9/26/90 - Mods to X11Helper to prevent core dump if run under shell
Magic Note #10 - 10/5/90 - Magic V4 for the DOS and OS/2
Magic Note #11 - 10/11/90 - reducing memory usage by 600k
Magic Note #12 - 12/19/90 - fixed bug in extflat that caused dropped R's.
Magic Note #13 - 12/19/90 - fixed bug in resis that caused coredump.
Magic Note #14 - 12/19/90 - new version of scmos.tech to support res extraction.
Magic Note #15 - 12/19/90 - contact line in tech file improperly documented
-------------------------------------------------------------------------------

--Bob