The IDPROM address space provides system information including Machine Type, Serial Number, Ethernet Address, and Manufacturing Date. This information may be stored in an IDPROM, NVRAM, or EEPROM. The 32 Bytes of IDPROM content are shown below.

The Machine Type and Serial Number are combined to create the Hostid. Licensed software may use the Hostid.

Prior to the SPARCstation 10, the Machine Type was used by the operating system to identify the architecture and the architecture implementation.

Beginning with the SPARCstation 10, systems are not assigned a unique Machine Type. The device tree in the Open Boot PROM provides the system characteristics to the operating system. The high-order bit of the Machine Type is set to 1. The lower 7 bits of the Machine Type and Serial Number fields are used at Sun's discretion.

The alpha-numeric code on the NVRAM barcode label can be used by Sun to create a duplicate NVRAM. Provide this information when ordering a replacement NVRAM.

IDPROMs, NVRAMs, and EEPROMs are not interchangeable.

Programmed components that have a unique machine type are not interchangeable. For example, a new NVRAM is required when an SS2 (55xxxxxx) is upgraded to an SS20 (72xxxxxx).

Different component types are not interchangeable between systems. For example, a new NVRAM is required when an SS4 is upgraded (48T08) to an Ultra 1 Model 140 (48T59).

The 48T08 and 48T18 have the same pin count as the 48T59 but they are not pin compatible with the 48T59.

The NVRAM also contains a Time of Day clock. Accuracy of the clock is typically +/- 1 minute per month at 25°C. The 32,768Hz oscillator is tested not to exceed +/- 1.53 minutes per month (35PPM) error rate at 25°C.

NVRAM Component Types

MK48T02 100-1628-01    150ns Consumption life ~= 3.3 yrs TOPHAT battery	MK48T08 100-2822-01    150ns Consumption life ~= 10 yrs TOPHAT battery	MK48T18 100-3923-01    150ns Consumption life ~= 10 yrs TOPHAT battery	MK48T59 100-4316-01    70ns Consumption life ~= 7 yrs CAPHAT battery
MK48T02 100-1628-01    150ns Consumption life ~= 3.7 yrs CAPHAT battery	MK48T08 100-2822-02    100/150ns Consumption life ~= 11 yrs CAPHAT battery	MK48T18 100-4196-01    150ns Consumption life ~= 11 yrs CAPHAT battery	MK48T59 100-4007-01    70ns Consumption life ~= 7 yrs CAPHAT battery
	MK48T08 100-3528-01    100ns Consumption life ~= 10 yrs TOPHAT battery		MK48T59 100-5800-01    70ns Consumption life ~= 7 yrs CAPHAT battery
	MK48T08 100-4195-01    150ns Consumption life ~= 11 yrs CAPHAT battery

NVRAM Battery Types

TOPHAT Battery		CAPHAT Battery		SNAPHAT Battery
	A TOPHAT contains a battery and crystal. It is soldered to the integrated circuit and sealed with epoxy during assembly.		A battery and crystal are soldered to the integrated circuit. The part is then inserted into an epoxy filled CAPHAT.		A removable SNAPHAT contains the battery and crystal. There is no Sun part number for this part that is used in the RSM Array 2000 and A1000.