DOSWedge does not run in a DOS Window under Windows
However it works fine when you start the PC in Command Prompt mode
(DOS mode).
SYMPTOMS
When you are running Windows 98 Second Edition or Windows Millennium
Edition (ME) on a computer that supports the Advanced Configuration
and Power Interface (ACPI) specification, MS-DOS-based programs
that use the Extended Communication Service Int 14h function 05
do not work during the first attempt. To observe this behavior,
use the Mode.com tool, type MODE COMx:19200 , and then press ENTER.
You then receive the following error message:
Function not supported
on this computer.
NOTE : The information in this article is applicable only if you
are able to start your computer to an MS-DOS prompt and you are
able to run the preceding command successfully. If you receive an
error message when you run the preceding command, your computer's
Basic Input/Output System (BIOS) does not support the extended communication
INT 14h function 05 command. For additional information about this
issue, click the article number below to view the article in the
Microsoft Knowledge Base:
Q119595
- Function Not Supported on This Computer
CAUSE
This behavior can occur because the virtual communication device
(Vcd.vxd) incorrectly initializes the default state of the COM ports
for MS-DOS virtual machines (VMs) when you start your computer because
the COM ports have already been detected and powered off. The virtual
COM ports are initialized with 0xFF for all of its states instead
of the actual values of the port. Each time a new VM is created,
the default state that was detected at startup is copied to the
VM. Because the COM ports are trapped and virtualized, some of the
responses to in/out commands are based on the default state at startup
instead of the current state of the hardware. There are many in/out
commands that non-virtualize the port. When this occurs, power is
applied to the port, the current state is copied into the virtual
settings, and the COM ports operate properly.
RESOLUTION
To work around this behavior, disable the power management of the
COM ports:
- Use Registry Editor (Regedit.exe) to locate the EnablePowerManagement
value in the following registry key:
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\VxD\VCOMM
- On the Edit menu, click Modify , change 01
to 00, and then click OK .
- Quit Registry Editor.
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