Path: utzoo!attcan!uunet!lll-winken!lll-tis!ames!necntc!necis!mrst!apollo!pato
From: pato@apollo.COM (chc 02 rd)
Newsgroups: comp.sys.apollo
Subject: Re: adb missing ...
Message-ID: <3e3043cd.12edf@apollo.COM>
Date: 31 Aug 88 14:28:00 GMT
References: <8808291425.AA04608@richter.mit.edu>
Reply-To: pato@apollo.COM (Joe Pato)
Organization: Apollo Computer, Chelmsford, MA
Lines: 57

In article <8808291425.AA04608@richter.mit.edu> krowitz@RICHTER.MIT.EDU (David Krowitz) writes:
>I believe I saw a message a while ago about an undocumented switch
>(of course!) to DBX which allowed you to debug the machine code. I
>think the switch was -DB (or maybe it was the command DB give after
>you started DEBUG, I can't remember which). If someone has been
>keeping an archive of the postings, maybe they can search back
>through them.
>
>
> -- David Krowitz

The domain/ix and domain/os is the standard bsd4.3 DBX augmented to provide
source file display (a la /com/debug) and modified to understand a 68000
architecture instead of a VAX architecture.  DBX always allows you to debug
machine code.  To examine disassembled machine instructions use:

(dbx) <location>/<number>i      /* prints <number> machine instructions
                                ** beginning at location <location>
                                */

e.g.,
(dbx) 0xb50a /5i
0000b50a   LINK.w      a6,#-8
0000b50e   MOVEM.l     d2-d6/a2-a5,-(a7)
0000b512   MOVEA.l     a0,a5
0000b514   MOVE.l      (8.w,a6),d3
0000b518   MOVEA.l     (C.w,a6),a2

or

(dbx) &main/3i                  /* main is a function in the program :-) */
0000b50a   LINK.w      a6,#-8
0000b50e   MOVEM.l     d2-d6/a2-a5,-(a7)
0000b512   MOVEA.l     a0,a5

or

(dbx) ($pc)/3i                  /* $pc is the program counter */
0000b51e   PEA.l       (1A44.w,a5)
0000b522   MOVEA.l     (-7AC.w,a5),a0
0000b526   JSR         (a0)


"stepi" is the command for stepping by instructions, similarly stopi, tracei,
nexti

$pc is the program counter
$a0 ... $a7 are the address registers
$d0 ... $d7 are the data registers
$sp is an alias for $a7
$db is an alias for $a6

The manual page for dbx describes these facilities under the section 
"Machine Level Commands".  The only thing that it seems to be missing is the
the definition of the 68000 registers instead of the VAX register set.

  Joe Pato                UUCP: ...{attunix,uw-beaver,brunix}!apollo!pato
  Apollo Computer Inc.  NSFNET: pato@apollo.com