Aihnss.104 fa.info-micro utzoo!duke!decvax!ucbvax!ihnss!karn Fri Jul 3 01:33:43 1981 CMOS hardware debugging To: ucbvax!info-micro@mit-ai Re: CMOS hardware debugging Does anybody out there have extensive experience with debugging CMOS hardware? What we have is a CMOS microcomputer that sometimes works and sometimes doesn't. The design is good, as several others have been built and work fine. The guys working on it seem to think the only cause left is a CMOS "floater", that is, a gate input normally tied high or low has broken inside the package and is floating. Unlike TTL, which normally floats "high", CMOS's high input impedance will allow an open gate to hold a high or low charge for quite some time. If the charge matches what the input is supposed to be at, fine; if not, the circuit doesn't work. Any ideas on ways to make a "floater" show itself long enough to be found by the usual logic tracing methods? Phil Karn ihnss!karn ----------------------------------------------------------------- gopher://quux.org/ conversion by John Goerzen of http://communication.ucsd.edu/A-News/ This Usenet Oldnews Archive article may be copied and distributed freely, provided: 1. There is no money collected for the text(s) of the articles. 2. The following notice remains appended to each copy: The Usenet Oldnews Archive: Compilation Copyright (C) 1981, 1996 Bruce Jones, Henry Spencer, David Wiseman.