AMD AMD-K6-2/400 User Guide - Page 171
STEP Field., EBF[2:0] Field., Table 28., Processor-to-Bus Clock Ratios
View all AMD AMD-K6-2/400 manuals
Add to My Manuals
Save this manual to your list of manuals |
Page 171 highlights
23542A/0-September 2000 Preliminary Information AMD-K6™-2E+ Embedded Processor Data Sheet STEP Field. This read-only field contains the stepping ID. This is identical to the value returned by CPUID standard function 1 in EAX[3:0]. EBF[2:0] Field. This read-only field contains the effective value of the BF divisor supplied to the processor's internal PLL, which allows the BIOS to determine the frequency of the host bus. The core frequency must first be determined using the Time Stamp Counter (TSC) method (see "Time Stamp Counter" on page 46). The core frequency is then divided by the processor-to-bus clock ratio as determined by the EBF field (see Table 28). The result is the frequency of the processor bus. Table 28. Processor-to-Bus Clock Ratios State of EBF[2:0] 100b 101b 110b 111b 000b 001b 010b 011b Processor-to-Bus Clock Ratio 2.0x1 3.0x 6.0x 3.5x 4.5x 5.0x 4.0x 5.5x Notes: 1. The AMD-K6-2E+ processor does not support the 2.5x ratio supported by earlier AMD-K6 proces- sors. Instead, a ratio of 2.0x is selected when EBF[2:0] equals 100b. Chapter 6 AMD PowerNow!™ Technology 149