PSS ID Number: 196123
Article Last Modified on 10/21/1999
The information in this article applies to:
- Microsoft Win32 Device Driver Kit (DDK) Windows 98
This article was previously published under Q196123
SYMPTOMS
Under Windows 98, PCMCIA devices used with Texas Instruments (TI) 113x
CardBus controllers may fail to receive memory windows below 1 megabyte
(MB). Specifying a specific configuration tuple memory address below 1 MB
does not work, nor does using an .inf file override to force the window
below 1 MB.
CAUSE
TI 113x CardBus controllers can only address memory windows that are mapped
into a single 16-MB frame. Windows 95 OSR2 maps this 16-MB frame to the
low 16 MB of physical memory, meaning that all memory windows must reside
below 1 MB because systems usually have at least 16 MB of RAM.
However, Windows 98, by default, maps the 16-MB frame above the top of
physical memory, meaning that memory windows must also reside above system
RAM.
RESOLUTION
In Windows 98, Cbss.vxd uses a registry entry to override the default TI
113x 16-MB frame mapping location. If the registry location below contains
an entry of any name with a value of 2, CBSS maps the controller's 16-MB
frame to the low 16 MB of physical memory, just as Windows 95 OSR2 does:
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\VxD\CBSS\Hacks
This allows memory windows to be mapped below 1 MB.
You can use the following line in an AddReg section in the .inf file to
force this behavior:
HKLM,System\CurrentControlSet\Services\VxD\CBSS\
Hacks,TIForceLow,3,02, 00,00,00
NOTE: This line should not include any breaks in your .inf file.
NOTE: The value name TIForceLow is arbitrary. Any name works successfully.
STATUS
This behavior is by design.
Keywords: kbprb KB196123
Technology: kbAudDeveloper kbWin32DDK98 kbWin32DDKSearch kbWin32sSearch kbWin98search kbWinDDKSearch