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Path: sserve!manuel!munnari.oz.au!uunet!stanford.edu!agate!soda.berkeley.edu!wjolitz From: wjolitz@soda.berkeley.edu (William F. Jolitz) Newsgroups: comp.unix.bsd Subject: Re: More on NMI problems. Date: 4 Sep 1992 18:26:47 GMT Organization: U.C. Berkeley, CS Undergraduate Association Lines: 34 Message-ID: <1889p7INN5sn@agate.berkeley.edu> References: <1992Sep2.123248.17492@ponds.uucp> NNTP-Posting-Host: soda.berkeley.edu In article <1992Sep2.123248.17492@ponds.uucp> rivers@ponds.uucp (Thomas David Rivers) writes: >Well, I got much advice on my NMI problems; indicating that I probably >did, in fact, have a bad memory chip on my machine. >So; I grabbed testext.exe from SIMTEL20 and let it have at the machine, >to determine which chip was bad, etc.... I missed your earlier inquiry, but I thought I should post a notice regarding "trap 19" problems. In particular, a student in Linkoping University sent me a fax regarding a problem with booting: he would get a "trap type 19 code..." message and the system would panic. Trap type 19 indicates an nmi trap (see trap.h). In this particular case, the problem was localized to the motherboard (a 486DX 33MHz ISA, made in Taiwan). There are two possibilities in this situation: 1. Bad memory parity. This could be a bad memory chip (run memory tests to confirm). However, it should be noted that some cheap boards have BIOS's which do not initialize memory correctly. In this case, one must clear memory blindly BEFORE touching it. If it is an inadaquate board, one might want to get a better (in-spec) one and use the other one for MS-DOS. 2. There is a difference between "expanded" (e.g. LIM) memory and "extended" (e.g. above 0x100000) memory. If any memory is allocated to "expanded" memory, then problems will occur. A number of people are experiencing 1) and 2) and have written me accordingly. I hope this helps isolate a few of those "mystery" problems. Lynne Jolitz.