Miscellaneous Hardware Stuff
Pentium® II/Pentium® Pro Signal Differences
The external signals associated with the Pentium® Pro and Pentium® II processors differ as described in Table 26-1 on page 679.
| Signal(s) | Description |
|---|---|
| BR[3:0]# | While the Pentium® Pro processor implemented BR[3:0]#, the Pentium® II processor only implemented BR[1:0]#. For additional information, refer to “The FSB Arbitration Scheme” on page 676. |
| BSEL# | Bus Select. Output. Tells the frequency generator on the system board the frequency of the BCLK desired by the processor. The frequency was defined by the combination of the processor, chipset and clock synthesizer. |
| EMI | Electromagnetic Interference. The Slot 1 connector included five pins that were used to control EMI. |
| SLOTOCC# | Slot Occupied. In conjunction with the voltage ID bus (VID[4:0]; see “Voltage Identification” on page 680), this signal was used to identify whether the second Slot 1 connector (in a dual processor system) was occupied by a processor cartridge, a terminator card, or was unoccupied. See Table 26-2 on page 680. |
| SLP# | Sleep. Input. Power conservation pin. For additional information, refer to “Pentium® II Power Management Features” on page 683. |
Voltage Identification
The processor's Voltage ID output pins tell the system board voltage regulator what operating voltage is required by the processor die.
While the Pentium® Pro processor had four voltage ID pins, the Pentium® II (and the slot 1 connector) had five pins, designated VID[4:0]. On the substrate, each of these pins was either an open or shorted to ground (Vss). The power supply had to either supply the requested processor core voltage (VccCore) or disable itself. In conjunction with the SLOTOCC# (Slot Occupied) signal, the VID bus could be used to detect the presence or absence of a processor core or a cartridge installed in the other slot 1 connector (in a dual processor system).
In a dual-Pentium® II system, a test tool (e.g., a probe tool) can determine the occupant of the second Slot 1 connector by observing the SLOTOCC# pin and the VID (voltage ID) pins. For more information, refer to “Pentium® II/Pentium® Pro Signal Differences” on page 679.