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Q87929: PRB: CTRL+BREAK, CTRL+ALT+SYSRQ, CTRL+C Do Not Return Control

Article: Q87929
Product(s): Microsoft Programming Utilities
Version(s): 4.0,4.01,4.05,4.1
Operating System(s): 
Keyword(s): kb16bitonly
Last Modified: 26-JUN-2001

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The information in this article applies to:

- Microsoft CodeView for MS-DOS, versions 4.0, 4.01, 4.05, 4.1 
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SYMPTOMS
========

When debugging an MS-DOS program using CodeView 4.0, 4.01, 4.05, or 4.1 the
CTRL+C, CTRL+BREAK, and CTRL+ALT+SYSRQ key combinations do not return control to
CodeView as they do with earlier CodeView versions.

CAUSE
=====

This behavior is by design. The DPMI server (Windows or 386MAX) traps these
interrupts for other purposes.

MORE INFORMATION
================

There are three ways to work around this limitation.

- Run CodeView outside of Windows and without 386MAX loaded. Without a DPMI
  server, the break should occur normally. Drivers like HIMEM, EMM386, and QEMM
  can be used to provide access to extended memory. Note that if EMM386.EXE is
  used, VCPI memory is provided and the recommended settings for EMM386.EXE
  change when running CodeView without Windows. Uncomment the following line in
  the CONFIG.SYS file to change the settings accordingly, or remove EMM386.EXE
  (then HIMEM will provide XMS memory)

  rem device=c:\windows\emm386.exe m9 2048 ram

  Note that 2048 might be too low a setting in some cases.

- Set strategic breakpoints in your code to force return of control.

- Break when you know an MS-DOS function is being called. During an MS-DOS
  interrupt, breaks should occur normally.

Additional query words: 4.00 4.10

======================================================================
Keywords          : kb16bitonly 
Technology        : kbAudDeveloper kbCodeView kbZNotKeyword3 kbCodeView400DOS kbCodeView401DOS kbCodeView405DOS kbCodeView410DOS
Version           : :4.0,4.01,4.05,4.1

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