Table of Contents
Advertisement
AMD Athlon™ XP Processor Model 8 Data Sheet
76
Preliminary Information
Table 26. FID[3:0] Clock Multiplier Encodings
2
FID[3:0]
0000
0001
0010
0011
0100
0101
0110
0111
1000
1001
1010
1011
1100
1101
1110
1111
Notes:
1. All ratios greater than or equal to 12.5x have the same FID[3:0] code of 0011b, which causes
the SIP configuration for all ratios of 12.5x or greater to be the same.
2. BIOS initializes the CLK_Ctl MSR during the POST routine. This CLK_Ctl setting is used with all
FID combinations and selects a Halt disconnect divisor and a Stop Grant disconnect divisor.
For more information, refer to the AMD Athlon™ and AMD Duron™ Processors BIOS,
Software, and Debug Developers Guide, order# 21656.
The FID[3:0] signals are open-drain processor outputs that are
pulled High on the motherboard and sampled by the chipset to
determine the SIP (Serialization Initialization Packet) that is
sent to the processor. The FID[3:0] signals are valid after
PWROK is asserted. The FID[3:0]signals must not be sampled
until they become valid. See the AMD Athlon™ System Bus
Specification, order# 21902 for more information about
Serialization Initialization Packets and SIP protocol.
The processor FID[3:0] outputs are open-drain and 2.5-V
tolerant. To prevent damage to the processor, if these signals
are pulled High to above 2.5 V, they must be electrically
isolated from the processor. For information about the FID[3:0]
isolation circuit, see the AMD Athlon™ Processor-Based
Motherboard Design Guide, order# 24363.
Pin Descriptions
Processor Clock to SYSCLK Frequency Ratio
11
11.5
12
≥ 12.5
1
5
5.5
6
6.5
7
7.5
8
8.5
9
9.5
10
10.5
25175H—March 2003
Chapter 11
Advertisement
Table of Contents
