Device IDs are unique ASCII strings that are created by enumerators to identify a hardware device. IDs are made up of three distinct parts, separated by a backslash. The first part of the ID identifies the enumerator that created the ID. The second part is the ID itself.
If this part of the string begins with an asterisk ("*"), this is an EISA-format ID, which are three letters followed by four hexadecimal digits. The 3-letter prefixes are assigned on a per-company basis and hardware vendors must only use those letters assigned to their company, or the PNPxxxx identifiers discussed in the following. EISA identifiers may be obtained from:
If you are a hardware manufacturer building ISA Plug and Play adapter boards, you are expected to procure your own three letter EISA identifier and assign your own IDs for your hardware. EISA identifiers may be obtained from:
BCPR Services, Inc.
< P.O. Box 11137
< Spring, Texas 77391-1137
< (713)251-4770 (phone)
< (713)251-4832 (fax)
Many enumerators generate EISA IDs when enumerating devices, and the "*" indicates that the ID comes from this generic pool, thus allowing setup to select the appropriate driver regardless of which enumerator created the ID. An ID that does not start with an "*" will require setup information specific to the enumerator that created the ID to find the appropriate driver. The third part of the ID is a unique instance number for this computer. This is used to distinguish two or more identical devices in a single computer from one another. For example, two COM ports require two unique instances.
Since many devices do not have an EISA ID, Microsoft has defined IDs for every device that Windows 95 supplies drivers for. We have reserved the EISA manufacturer's ID "PNP" and defined a set of IDs for base system components:
Other base system components are numbered in the same way. The complete current list of compatibility IDs is available on Compuserve in the PLUGPLAY forum, under the filename DEVIDS.ZIP.
ISA device IDs have the following form:
ISAPNP\device ID+_DEV0000, 0001, ...\serial number
In this example, device ID is taken from the first four bytes of the card. The entries for _DEV numbers are required only if there are many devices on the card.
The following table gives some sample ISA device IDs.
| Device ID | Description |
|---|---|
| ISAPNP\FDC0000\00000012 | future domain |
| ISAPNP\ADP1522_DEV0000\E8124123 | Adaptec SCSI device (function 0) |
| ISAPNP\ADP1522_DEV0001\E8124123 | Adaptec floppy device (function 1) |
For PCMCIA, the device ID is created from tuple information on the card. The goal is to create a unique ID for each card.
The ID is created by concatenating the PCMCIA prefix, the manufacturer-name string, the product-name string, a 16-bit CRC, and the instance value for the card.
PCMCIA\manufacturer_name-product_name-crc\instance
A PCMCIA device identifier might look like the following example:
PCMCIA\MEGAHERTZ-XJ124FM-936B
The CRC is created from the following tuple data:
If the CISTPL_VERS_1 tuple is not available or the manufacturer name is NULL, the string "UNKNOWN_MANUFACTURER" is used for the manufacturer name.
PCMCIA\UNKNOWN_MANUFACTURER_crc\instance
The total length of the device ID string is limited to 128 characters, including the null terminator. The manufacturer and product name are truncated, if necessary, to maintain this length restriction in the ID string.
The characters in the manufacturer and product name strings that are greater than or equal to a space (0x20) or less than (0x7F) will be copied into the name string. Any characters outside this range are skipped. This restriction makes it easier to include these characters in the .INF files for the device.