Appendix B BIOS POST Codes B-5
38h Reserved.
39h Test DMA page registers.
3Ah Reserved.
3Bh Reserved.
3Ch Test 8254.
3Dh Reserved.
3Eh Test 8259 interrupt mask bits for channel 1.
3Fh Reserved.
40h Test 8259 interrupt mask bits for channel 2.
41h Reserved.
42h Reserved.
43h Test 8259 functionality.
44h Reserved.
45h Reserved.
46h Reserved.
47h Initialize EISA slot.
48h Reserved.
49h 1. Calculate total memory by testing the last double word of each
64K page.
2. Program-write allocation for AMD K5 CPU.
4Ah Reserved.
4Bh Reserved.
4Ch Reserved.
4Dh Reserved.
4Eh 1. Program MTRR of M1 CPU.
2. Initialize the L2 cache for P6 class CPU and program CPU with
proper cacheable range.
3. Initialize the APIC for P6 class CPU.
4. On MP platform, adjust the cacheable range to a smaller one in
case the cacheable ranges between each CPU are not identical.
4Fh Reserved.
50h Initialize USB keyboard and mouse.
TABLE B-1 BIOS Port 80 POST Codes (Continued)
Post Code Description
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