Last Passing Maneuver: Tualatin 1266 With 512 kB Versus Athlon And P4

10 New Pins

On the left, the PIII Coppermine, on the right the PIII Tualatin: the 370 pins are a constant. Only the SMD components are smaller than the predecessor's.

Intel already did it once when moving from the Celeron/Mendocino 533 (black PPGA case) to the Celeron/Coppermine 533A (green FCPGA case): new pins required modifications on motherboards. The Tualatin has pins that have been altered too. The pin count of the 370 has not been tinkered with, because that would have meant a new socket.

The chart below shows the pin IDs that were replaced by Intel. Unlike Coppermine, all others retain the same significance. The AF36 is one of the important pins. Its voltage functions to allow the chipset to recognize the processor type. If the AF36 has Vss voltage, then it is a PIII Coppermine; otherwise, it is a Tualatin that occupies socket 370. Depending on the condition, the FSB buffer mode on the i815 chipset and the appropriate Vtt voltage (1.5 or 1.25V) are set.

Pin PIII Coppermine PIII Tualatin Descripton for Tualatin
AF36 Vss NC for CPU type detection
AB36 VccCMOS Vtt pull to Vtt
AG1 Vss Vtt switch between Vtt and Vss, depending on AF36
AK4 Vss VTTPWGRD pull to VTTPWRGD with 1 kOhm resistor
AK36 Vss VID[25mV] pull to VID[25mV]
AN3 Vss DYN_OE pull to Vtt with 1 kOhm resistor
AM2 RESET# NC Not connected
X4 NC Vss pull to RESET# with 1 kOhm resistor
AJ3 Vss RESET# Not connected
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