Microsoft KB Archive/170084

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HOWTO: Add PCMCIA Support to a Windows NT Device Driver


The information in this article applies to:

  • Microsoft Win32 Device Driver Kit (DDK) for Windows NT, versions 3.51, 4.0


PCMCIA support under Windows NT is in the form of basic PC Card enabling. Such PCMCIA features as dynamic configuration and hot-plugging are unsupported. Basically, a developer writes an ISA device driver and ensures that the PC Card is configured correctly (either via the CIS tuple information or the registry overrides described below). The ISA driver checks the registry to see if the card is configured and gets the resources from the resource list created by Pcmcia.sys. The ISA driver is also responsible for claiming the card resources via IoReportResourceUsage or a similar mechanism.

For additional information about how to mask specific IRQs to PCMCIA devices as well as detailed information about the InterruptMask value of the PCMCIA registry key that controls IRQ masking, please see the following articles in the Microsoft Knowledge Base:

Q168303 Masking IRQs for PCMCIA Devices


For Pcmcia.sys to recognize the card, there must first be an entry in the PCMCIA database. This database is stored in the Windows NT registry. In the following discussion, note that HKLM indicates HKEY_LOCAL_MACHINE and CCS indicates CurrentControlSet.

WARNING: Modifying the registry can cause the system to become unstable and may cause the system to become unusable (requiring a reinstallation). Do not modify the registry unless you understand the implications of any changes you are making.

Note that the Pcmcia.sys driver shipped with Windows NT 4 does not support PCCards with a DMA (direct memory access) interface. Also, there are no registry overrides that can be used to configure these DMA-capable PCCards.

Add PC Card Information to the PCMCIA Database

  1. Under HKLM\SYSTEM\CCS\Services\Pcmcia\DataBase add a key for Manufacturer ID. This information is in the Level 1 Version/Product Information Tuple. The Manufacturer ID is the first ASCII string after the Minor Version Number. For example:

          HKLM\SYSTEM\CCS\Services\Pcmcia\DataBase\XYZ Corp 
  2. Under Manufacturer ID, add a key for the Device ID. The Device ID is the second ASCII string (just after the Manufacturer ID). For Example:

          HKLM\SYSTEM\CCS\Services\Pcmcia\DataBase\XYZ Corp\XYZ device 
  3. For PCMCIA.SYS to configure the PC Card, you must specify the name of a driver under the Device ID key. Add this as a value under the Device ID key:

          Driver : REG_SZ : Xyz 

    Note that the value of the driver specified here does not need to match the "real" driver's name. For example, the driver that actually controls a card may be Abc.sys and have a service key name "Abc", but the driver name specified in the PCMCIA database is "Xyz". In this case, the driver Abc.sys would look for the resource information under "Xyz" in the Hardware key (described below).

    Finding the PC Card Resources

    After adding the PCMCIA database information and rebooting, the Pcmcia.sys driver attempts to configure the card according to the CIS tuple data. If the tuple data is successfully parsed and the PC Card configured, PCMCIA creates a resource list under the following key:


    There should be a value under this key of the name specified in the PCMCIA database entry for this particular card. For the example presented thus far, the PCMCIA database described driver "Xyz". So, under the PCMCIA PCCARDS key should be a value similar to the following:


    If the ISA driver for the PC Card finds this value, then the PC Card is configured and ready to go. The resource descriptor layout is described in the Windows NT DDK. The ISA driver should parse this resource list to get the information and map the I/O and memory spaces as required, as well as configure the interrupt.

    If the resource list is found in the dynamic HARDWARE key, then the card is configured and usable. If the resource list is not there, then the card is not in the socket, or an override is required to make Pcmcia.sys configure the card.

    There may be more than one resource list value under this key, so make sure to check that the value name matches the driver name specified in the PCMCIA database.

    Using Registry Overrides for PCMCIA Cards

    For PCMCIA overrides to be processed, they must specify either an interrupt or I/O port address (or both). If the card does not use either, then you will have to select a dummy I/O port address to force the override to be accepted.

  4. Create a new driver key in the Services key. The name for this key should match the key specified in the PCMCIA database for this specific PCCARD, with a single digit ("1" through "9") appended to it. For example:

  5. Under the new driver key, add a Parameters key. For example:

  6. Under the Parameters key, the following value is required. If it is not present or set to zero, the PCMCIA driver will not use this configuration and will search for another configuration in the registry. Pcmcia.sys will stop searching for configurations as soon as it finds a valid override. This is why you cannot use more than one PC Card with a specific Manufacturer ID and Device ID.

          Pcmcia : DWORD : 1 
  7. Under the Parameters key, add the optional keywords as needed. Examples include:

          AttributeMemorySize : DWORD : 0x1000
          InterruptNumber : DWORD : 0xf
          IoBaseAddress : DWORD : 0x170
          IoBaseAddress_1 : DWORD : 0x376
          IoLength : DWORD : 0x8
          IoLength_1 : DWORD : 0x2 

Possible override values under:

   HKLM\SYSTEM\CCS\Services\Pcmcia\DataBase\XYZ Corp\XYZ device

Value Name                     Data Type  Description
-------------------------      ---------  -------------------------------
CcrBase                        REG_DWORD  Configuration register base
PortWidth16                    REG_DWORD  1=16 bit accesses to I/O space
Driver                         REG_SZ     Driver name
CardMemorySize                 REG_DWORD  [0] Card memory length
CardMemorySize_1               REG_DWORD  [1] Card memory length
AttributeMemorySize            REG_DWORD  [0] Attribute memory length
AttributeMemorySize_1          REG_DWORD  [1] Attribute memory length 

Possible override values for:


Value Name                     Data Type  Description
-------------------------      ---------  -------------------------------
Pcmcia                         REG_DWORD  1=enable this configuration
InterruptNumber                REG_DWORD  Interrupt value

IoBaseAddress                  REG_DWORD  [0] I/O port base address
IoLength                       REG_DWORD  [0] I/O port length

IoBaseAddress_1                REG_DWORD  [1] I/O port base address
IoLength_1                     REG_DWORD  [1] I/O port length

MemoryMappedBaseAddress        REG_DWORD  [0] Host base memory
MemoryMappedSize               REG_DWORD  [0] Host base memory length
PCCARDMemoryWindowOffset       REG_DWORD  [0] Card base (host base offset)
Address_16                     REG_DWORD  1=16-bit memory access

MemoryMappedBaseAddress_1      REG_DWORD  [1] Host base memory
MemoryMappedSize_1             REG_DWORD  [1] Host base memory length
PCCARDMemoryWindowOffset_1     REG_DWORD  [1] Card base (host base offset)
Address1_16                    REG_DWORD  1=16-bit memory access

MemoryMappedBaseAddress_2      REG_DWORD  [2] Host base memory
MemoryMappedSize_2             REG_DWORD  [2] Host base memory length
PCCARDMemoryWindowOffset_2     REG_DWORD  [2] Card base (host base offset)
Address2_16                    REG_DWORD  1=16-bit memory access

MemoryMappedBaseAddress_3      REG_DWORD  [3] Host base memory
MemoryMappedSize_3             REG_DWORD  [3] Host base memory length
PCCARDMemoryWindowOffset_3     REG_DWORD  [3] Card base (host base offset)
Address3_16                    REG_DWORD  1=16-bit memory access

PCCARDAttributeMemoryAddress   REG_DWORD  [0] Attribute memory
PCCARDAttributeMemorySize      REG_DWORD  [0] Attribute memory length
PCCARDAttributeMemoryOffset    REG_DWORD  [0] Attribute memory offset
AttributeMemory_16             REG_DWORD  1=16-bit memory access

PCCARDAttributeMemoryAddress_1 REG_DWORD  [1] Attribute memory
PCCARDAttributeMemorySize_1    REG_DWORD  [1] Attribute memory length
PCCARDAttributeMemoryOffset_1  REG_DWORD  [1] Attribute memory offset
AttributeMemory1_16            REG_DWORD  1=16-bit memory access

ModemFunction                  REG_DWORD  1=multifunction modem device

PCCARDReadyInterrupt           REG_DWORD  * Not implemented * 

Additional query words:

Keywords : kbDDK kbOSWinNT351 kbOSWinNT400
Issue type : kbhowto
Technology : kbAudDeveloper kbWinDDKSearch kbWin32sSearch kbWin32DDKSearch kbWin32DDKNT351 kbWin32DDKNT400 kbWin32DDKNTSearch

Last Reviewed: April 5, 1999
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