AMD AMD-K6-2/500AFX Data Sheet - Page 226
Write Merge Buffer, AMD-K6, 2 Processor Data Sheet, Example., Table 41.
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AMD-K6®-2 Processor Data Sheet Preliminary Information 21850J/0-February 2000 Table 41. Valid Masks and Range Sizes (continued) Masks 111_1111_1000_0000b 111_1111_0000_0000b 111_1110_0000_0000b 111_1100_0000_0000b 111_1000_0000_0000b 111_0000_0000_0000b 110_0000_0000_0000b 100_0000_0000_0000b 000_0000_0000_0000b Size 16 Mbytes 32 Mbytes 64 Mbytes 128 Mbytes 256 Mbytes 512 Mbytes 1 Gbyte 2 Gbytes 4 Gbytes Example. Suppose that the range of memory from 16 Mbytes to 32 Mbytes is uncacheable, and the 8-Mbyte range of memory on top of 1 Gbyte is write-combinable. Range 0 is defined as the uncacheable range, and range 1 is defined as the writecombining range. Extracting the 15 most-significant bits of the 32-bit physical base address that corresponds to 16 Mbytes (0100_0000h) yields a physical base address 0 field of 000_0000_1000_0000b. Because the uncacheable range size is 16 Mbytes, the physical mask value 0 field is 111_1111_1000_0000b, according to Table 41. Bit 1 of the UWCCR register (WC0) is set to 0 and bit 0 of the UWCCR register is set to 1 (UC0). Extracting the 15 most-significant bits of the 32-bit physical base address that corresponds to 1 Gbyte (4000_0000h) yields a physical base address 1 field of 010_0000_0000_0000b. Because the write-combining range size is 8 Mbytes, the physical mask value 1 field is 111_1111_1100_0000b, according to Table 41. Bit 33 of the UWCCR register (WC1) is set to 1 and bit 32 of the UWCCR register is set to 0 (UC1). 206 Write Merge Buffer Chapter 8