IBM 560E manual Low, Bytes Hex 015 and Hex, Hex 017 018, 031, Byte Hex

Bits 3–2These bits are reserved.

Bit 1 When set to 1, this bit indicates that a coprocessor is installed.

Bit 0 When set to 1, this bit indicates that physical diskette drive 0 is installed.

Low

and

High

Base

Memory

Bytes (Hex 015 and Hex 016):

The

low

and high

base

memory bytes define the amount

of

memory

below

the

640KB

address

space.

The

value

in

these

bytes

represents

the

number of

1KB blocks of

base

memory.

For

example,

hex 0280

indicates 640KB. The

low

byte

is

hex

015;

the

high byte

is

hex

016.

Low

and

High

Expansion

Memory

Bytes

(Hex

017

and

Hex

018):

The

low

and

high expansion

memory

bytes

define

the

amount

of

memory

above

the

1MB

address

space.

The value in these bytes represents

the number of 1KB blocks of

expansion

memory. For

example,

hex

0800

indicates 2048KB. The

low

byte

is hex 017; the high

byte

is

hex

018.

Reserved

Bytes (Hex

01D–02D):

These bytes are reserved.

Configuration Checksum Bytes (Hex 02E and Hex 02F):

The

configuration checksum bytes contain the checksum

character for

bytes hex 010 through hex

02D

of

the

64-byte

CMOS

RAM. The

high

byte

is

hex

02E;

the

low

byte

is

hex

02F.

Low

and

High

Usable

Memory

Bytes

(Hex

030

and

Hex

031):

The low and high usable memory bytes

define

the

total

amount of

contiguous

memory

from

1MB

to

20MB.

The hexadecimal values in these bytes represent

the

number of 1KB

blocks of usable memory. For example,

hex

0800

is

equal

to

2048KB. The

low

byte

is

hex

30;

the

high

byte

is

hex

31.

Date-Century

Byte

(Hex

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 IBMbyte, refer to the Personal System/2 and Personal Computer BIOS .Interface

Reserved Bytes (Hex 033–07F): These bytes are reserved.

ThinkPad 560/560E System Board 2-25