KnowledgeBase Archive

An Archive of Early Microsoft KnowledgeBase Articles

View on GitHub

Q67584: Active Code Page Versus Selected Code Page

Article: Q67584
Product(s): Microsoft Disk Operating System
Version(s): MS-DOS:3.x,4.x,5.x,6.0,6.2,6.21,6.22
Operating System(s): 
Keyword(s): 
Last Modified: 17-DEC-2000

-------------------------------------------------------------------------------
The information in this article applies to:

- Microsoft MS-DOS operating system versions 3.1, 3.2, 3.21, 3.3, 3.3a, 4.0, 4.01, 5.0, 5.0a, 6.0, 6.2, 6.21, 6.22 
-------------------------------------------------------------------------------

SUMMARY
=======

The COUNTRY command in CONFIG.SYS can be used to specify a code page that CHCP
then reports. However, the code page is not really made active. The MODE command
reports "No code page has been selected" and KEYB reports "Active code page not
available from CON device."

This behavior is a result of the difference in the definitions of an "active"
code page and a "selected" code page. The system has a global "active" code page
that it attempts to use when accessing any code page supported device.
Additionally, each of these devices has a "selected" code page. The global
(active) code page and the individual device code page (selected) do not
necessarily match.

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

The COUNTRY command sets the initial active "global" code page, but does not
select that code page for each device. The CHCP command reports and changes the
global code page, and also attempts to select that code page for each of the
code page devices. You can bypass the CHCP command and change a device's
selected code page directly by using the MODE command as follows:

  MODE CON CODEPAGE SELECT=xxx

This selects code page xxx for the CONsole device without affecting the code page
used by the other devices or the global active code page.

In summary:

- COUNTRY sets the country information, and sets the initial global code page,
  but does not set code pages in the device drivers.

- MODE [CON PRN] CODEPAGE SELECT sets the code page used by a device driver,
  but does not affect the global active code page.

- CHCP sets the global code page, and issues the equivalent of a MODE [CON PRN]
  CODEPAGE SELECT command for each device it finds.

Complete code page installation includes use of a COUNTRY command, and the
loading of the CON and/or PRN device in the CONFIG.SYS, plus loading of NLSFUNC,
a MODE CON/PRN CODEPAGE PREPARE command, and a CHCP command in the
AUTOEXEC.BAT.

The following example (from page 331 of the "Microsoft MS-DOS User's Reference"
version 4.0) demonstrates the interactions of COUNTRY, MODE, and CHCP:

  CONFIG.SYS
  ----------
  country=049,,a:\country.sys
  device=display.sys con:=(ega,437,1)

  AUTOEXEC.BAT
  ------------
  nlsfunc
  mode con codepage prepare=((850)a:\ega.cpi)
  chcp 437

1. After booting:

   - CHCP reports 437 as the active code page.

   - MODE CON CODEPAGE reports that 437 is the active ("selected") code page
     for the CON device.

2. After issuing a CHCP 850 command:

   - CHCP reports 850 as the active code page.

   - MODE CON CODEPAGE reports 850 is the active code page for the CON device.

3. After issuing a MODE CON CODEPAGE SELECT=437 command:

   - CHCP reports 850 as the active code page.

   - MODE CON CODEPAGE reports 437 as the active code page for the CON device.

The "No code page has been selected" error occurs because a code page has not yet
been selected for the device with CHCP or a MODE CON CODEPAGE SELECT= command.
KEYB also suffers from the same problem: it requires that a code page be
selected for the device.

Additional query words: 6.22 3.30 3.30a 4.00 4.01 5.00 5.00a 6.00 6.20

======================================================================
Keywords          :  
Technology        : kbMSDOSSearch kbMSDOS321 kbMSDOS400 kbMSDOS320 kbMSDOS330a kbMSDOS621 kbMSDOS622 kbMSDOS620 kbMSDOS600 kbMSDOS310 kbMSDOS500 kbMSDOS330 kbMSDOS401 kbMSDOS500a
Version           : MS-DOS:3.x,4.x,5.x,6.0,6.2,6.21,6.22

=============================================================================

THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND. MICROSOFT DISCLAIMS ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL, CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. SOME STATES DO NOT ALLOW THE EXCLUSION OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES SO THE FOREGOING LIMITATION MAY NOT APPLY.