AdapterSettings Entry for SCSI Miniport under Windows 95 (140728)

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Scsiport.pdr actually looks in two different places in the registry for user settings to pass to the miniport via the ArgumentString parameter of the miniport's HwFindAdapter function. Each hardware device actually has two different keys in the registry -- the software key and the hardware key.

The hardware key contains information about the device, such as logical resource information, hardware ID, compatible device IDs, device descriptions, and so on. The hardware key for a device will lie under the bus type it belongs to, under the HKEY_LOCAL_MACHINE\Enum key. For example, a legacy ISA Adaptec 1542 SCSI adapter would have a hardware key registry similar to this:

    \\HKEY_LOCAL_MACHINE
      \Enum
        \Root
          \*ADP1542
            \0000
				

The \Root key indicates the device is a legacy (non-PnP) device, and the \0000 is the instance number for the device. Similarly, ISA PnP devices would be found under the \ISAPNP key, PCI devices would be under the \PCI key, etc. The hardware registry section for a device also contains an entry that points to the software registry key for that device. For example, the Adaptec adapter might have a Driver=SCSI\0000 value. This points to the software key for the device, which would be found under the following key in the registry:

    \\HKEY_LOCAL_MACHINE
      \System
        \CurrentControlSet
          \Services
            \Class
              \ScsiAdapter
                \0000
				

The software key for a device has driver information, such as the devloader for the device (*IOS in the case of SCSI adapters) and the driver for the device.

Scsiport.pdr will look in both the software and hardware registry sections of a SCSI adapter to find a parameter string to pass to the SCSI miniport's HwFindAdapter function. The subkey it looks for is AdapterSettings. Scsiport will look first in the software section and then in the hardware section for a matching subkey. The hardware section is searched only if the software section does not have a match.

NOTE: Users can create their own AdapterSettings parameter string using Device Manager by selecting Properties for the device, selecting the Settings property page, and entering appropriate information into the Adapter Settings edit control. The entered adapter settings will be stored in the hardware registry key for the device. This implies that an AdapterSettings string created by a user can be overridden by an AdapterSettings entry in the hardware key.