Lenovo ThinkPad 560Z TP 560Z Technical Reference Manual - Page 44
Low and High Expansion Memory Bytes X
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Bits 3-2 Bit 1 Bit 0 These bits are reserved. If set to 1, this bit indicates that a coprocessor is installed. If set to 1, this bit indicates that physical diskette drive 0 is installed. Low and High Base Memory Bytes (X'015' and X'016'): The low and high base memory bytes define the amount of memory below the 640-KB address space. The value in these bytes represents the number of 1-KB blocks of base memory. For example, X'0280' indicates 640 KB. The low byte is X'015'; the high byte is X'016'. Low and High Expansion Memory Bytes (X'017' and X'018'): The low and high expansion memory bytes define the amount of memory above the 1-MB address space. The value in these bytes represents the number of 1-KB blocks of expansion memory. For example, X'0800' indicates 2048 KB. The low byte is X'017'; the high byte is X'018'. Reserved Bytes (X'01D'-X'02D'): These bytes are reserved. Configuration Checksum Bytes (X'02E' and X'02F'): The configuration checksum bytes contain the checksum character for bytes X'010' through X'02D' of the 64-byte CMOS RAM. The high byte is X'02E'; the low byte is X'02F'. Low and High Usable Memory Bytes (X'030' and X'031'): The low and high usable memory bytes define the total amount of contiguous memory from 1 MB to 20 MB. The hexadecimal values in these bytes represent the number of 1-KB blocks of usable memory. For example, X'0800' is equal to 2048 KB. The low byte is X'30'; the high byte is X'31'. Date-Century Byte (X'032'): Bits 7 through 0 of the date-century byte contain the binary-coded decimal value for the century. For information about reading and setting this byte, refer to the IBM Personal System/2 and Personal Computer BIOS Interface. Reserved Bytes (X'033'-X'07F'): These bytes are reserved. 2-26 ThinkPad 560Z System Board