KB140729 - Using Windows 95 PCMCIA Card Services

MORE INFORMATION

If you feel you must use PCMCIA Card Services under Windows 95, please be aware of the following restrictions:

Many Card Services functions can only be called during AppyTime. Certain Card Services functions (particulary those that deal with resource allocation) make use of VxD services that can only be called during AppyTime. It is recommended that all calls to Card Services be made during AppyTime. The notification callback for a Card Services client occurs at AppyTime, so it is safe to make CS calls at that time.
The Card Services binding for VxDs under Windows 95 does not match the 32-bit binding defined by the PCMCIA 2.x specification. In Pnp.doc in the Windows 95 DDK, it states that PCCARD_Card_Service "follow the recommended binding in the PCMCIA Standards manual for 0:32 protected- mode clients." It then goes on to list these bindings as:
```
   AL - Function
   DX - Handle
   ESI - Pointer (32-bit offset)
   CX - ArgLength
   EBX - ArgPointer (32-bit offset)
   ---------------
   AX - Status
   CF - Success/Fail
						
```
This actually varies from the PCMCIA 2.x spec, which lists EDX as the handle (versus DX), ECX as the ArgLength (not CX), and EAX as the status (not AX). The bindings defined in Pnp.doc are correct for Windows 95, with the exception of the return status, which is actually returned in EAX, not AX.