Lenovo ThinkPad 560E 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

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Bits 3–2
These bits are reserved.
Bit 1
If set to 1, this bit indicates that a coprocessor is
installed.
Bit 0
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